Electrical actuation system for a drive

• US 5,172,798 A
• Filed: 06/08/1992
• Issued: 12/22/1992
• Est. Priority Date: 06/08/1992
• Status: Expired due to Term

• Current Assignee: Force Control Industries, Inc.
• Original Assignee: Easom Engineering and Manufacturing Corporation
• Inventors: Mabee, Brian D.
• Primary Examiner(s): Bonck, Rodney H.
• Application Number:
  US07/895,344
• Time in Patent Office: 197 Days
• Field of Search: 192/84 C, 192/48.2, 192/12 D, 192/18 B, 192/48.91, 188/161, 188/171, 74/661
• US Class Current: 192/18.00B
• CPC Class Codes: F16D 2121/20 using electromagnets
• CPC Class Codes: F16D 27/112 with flat friction surfaces, e.g. discs
• CPC Class Codes: F16D 55/00 Brakes with substantially-radial braking surfaces pressed together in axial direction, e.g. disc brakes similar clutches F16D13/38
• CPC Class Codes: F16D 67/06 electromagnetically actuated
• CPC Class Codes: Y10T 74/19014 Plural prime movers selectively coupled to common output

Abstract

An electrical actuation system for a drive utilizing one or more disc stacks having annular discs alternately connected with two or more drive components. A disc stack is directly selectively clamped by an armature of an armature assembly being magnetically attracted to an electromagnetic coil of an electromagnetic coil assembly upon energization of an excitation current in the electromagnetic coil. The armature has a zero air gap with respect to the electromagnetic coil when the disc stack is clamped. A plurality of armature springs are carried with the armature assembly and are compressed when the armature assembly biases against the disc stack, thereby accommodating wear of the discs. Clamping of the disc stack results in the two drive components connected therewith being interconnected. Upon the excitation current being switched off, the disc stack is no longer clamped and the two drive components are now unconnected. The electrical actuation system may be used in a clutch, brake or any number of clutch and brake combinations.

Claims

1. An electrical actuation system for a drive, the drive having a housing, the drive further having at least one disc stack mounted within the housing, the disc stack having a first side and a second side, a first thrust surface being provided within the housing adjacent the first side of the disc stack, the disc stack being composed of at least two sets of annular discs which are mutually interleaved, said electrical actuation system comprising:

an electromagnetic coil assembly located within and connected to the housing, said electromagnetic coil assembly comprising an electromagnetic coil and a pole piece, said pole piece being located with respect to said electromagnetic coil so as to be magnetizable thereby; and

an armature assembly located within the housing, said armature assembly comprising;

armature plate means selectively locatable within a first predetermined distance from said pole piece;

armature connection means for slidably connecting said armature plate means with respect to the housing so that said armature plate means may slide reciprocably between a first location whereat said armature plate means contacts said pole piece to a second location whereat said armature plate means is at said first predetermined distance from said pole piece;

spring take-up plate means resiliently connected with said armature plate means;

armature spring means for resiliently connecting said spring take-up plate means to said armature plate means, said armature spring means having a first end and a second end, said first end of said armature spring means being connected with said armature plate means, said second end of said armature spring means being slidably connected with said spring take-up plate means; and

second thrust surface means for selectively contacting the second side of the disc stack, said second thrust surface means being connected with said spring take-up plate means, said second thrust surface means being selectively locatable within a second predetermined distance from the second side of the disc stack;

wherein an excitation current supplied to said electromagnetic coil causes said armature plate means to be magnetically attracted to said pole piece and as a result thereof slide on said armature connection means toward said pole piece until contact therewith has been made whereupon said excitation current is reduced by a predetermined amount which provides sufficient magnetism to keep said armature plate means in contact with said pole piece, and wherein said first predetermined distance is longer than said second predetermined distance;

wherein further, the movement of said armature plate means into contact with said pole piece causes said armature spring means, said spring take-up plate means and said second thrust surface means to move with said armature plate means until said second thrust surface means forcibly abuts the second side of the disc stack, wherein still further, said armature spring means resiliently compresses in order to accommodate the difference between said first and second predetermined distances thereby supplying a predetermined biasing force to said second thrust surface means with respect to the second side of the disc stack so as to clamp the at least two sets of annular discs between the first thrust surface and said second thrust surface means.

2. The electrical actuation system of claim 1, wherein said armature connection means further comprises means for biasing said armature plate means away from said pole piece when no excitation current is supplied to said electromagnetic coil.

3. The electrical actuation system of claim 1, wherein said armature spring means comprises:

a plurality of armature spring bolts, each armature spring bolt having a first end and an opposite second end having a head, said spring take-up plate means being slidably connected with said plurality of armature spring bolts;

a plurality of spacers connected with said armature plate means, a respective spacer of said plurality of spacers being connected with each armature bolt at said first end thereof;

a plurality of armature springs, a respective armature spring of said plurality of armature springs being located on each armature bolt, said spring take-up plate being trapped on said plurality of armature bolts between said head thereof and said respective armature spring.

4. The electrical acutation system of claim 1, wherein said second thrust surface means comprises:

thrust plate means having a second thrust surface for selectively contacting the second side of the disc stack, said second thrust surface being selectively locatable within the second predetermined distance from the second side of the disc stack; and

bearing means for connecting said spring take-up plate means to said thrust plate means and for permitting mutual rotation therebetween.

5. The electrical actuation system of claim 4, wherein said armature spring means comprises:

a plurality of armature spring bolts, each armature spring bolt having a first end and an opposite second end having a head, said spring take-up plate means being slidably connected with said plurality of armature spring bolts;

a plurality of spacers connected with said armature plate means, a respective spacer of said plurality of spacers being connected with each armature bolt at said first end thereof; and

a plurality of armature springs, a respective armature spring of said plurality of armature springs being located on each armature bolt, said spring take-up plate being trapped on said plurality of armature bolts between said head thereof and said respective armature spring.

6. The electrical actuation system of claim 5, wherein said armature connection means further comprises means for biasing said armature plate means away from said pole piece when no excitation current is supplied to said electromagnetic coil.

7. The electrical actuation system of claim 1, wherein the disc stack comprises:

a first set of annular discs, said first set of annular discs being structured to connect selectively with respect to the drive;

a second set of annular discs, said second set of annular discs being structured to connect selectively with respect to the drive, said first set of annular discs being interleaved with said second set of annular discs; and

alignment pin means connected with said second set of annular discs for capturing each annular disc of said second set of annular discs and for capturing each annular disc of said first set of annular discs.

8. The electrical actuation system for a drive of claim 7, wherein said alignment pin means comprises:

a plurality of alignment pins, each alignment pin of said plurality of alignment pins having an alignment pin head at a first end thereof and a threaded opposite end;

a plurality of nuts, a nut of said plurality of nuts being threadably engaged on said threaded opposite end of each said alignment pin; and

a plurality of wave washers, wherein each annular disc of said second set of annular discs is separated from each adjacent annular disc of said second set of annular discs by a respective set of wave washers, one wave washer of said respective set of wave washers being carried on each said alignment pin of said plurality of alignment pins;

wherein each annular disc of said second set of annular discs is provided with a plurality of alignment pin holes, an alignment pin of said plurality of alignment pins extending through each alignment pin hole of said plurality of alignment pin holes, said first and second sets of annular discs being captured between said alignment pin head and said nut of each said alignment pin.

9. A clutch unit comprising:

a housing;

first drive shaft means rotatably connected with said housing;

second drive shaft means rotatably connected with said housing;

disc stack means having a first side and a second side, said disc stack means comprising;

a first set of annular discs connected with said first drive shaft means so as to be rotatable therewith and axially slidable with respect thereto; and

a second set of annular discs connected with said second drive shaft means so as to be rotatable therewith and axially slidable with respect thereto, said first set of annular discs being interleaved with said second set of annular discs;

first thrust surface means connected with said second drive shaft means adjacent said first side of said disc stack means;

an electromagnetic coil assembly located within and connected to said housing, said electromagnetic coil assembly comprising an electromagnetic coil and a pole piece, said pole piece being located with respect to said electromagnetic coil so as to be magnetizable thereby; and

an armature assembly located within said housing, said armature assembly comprising;

armature plate means selectively locatable within a first predetermined distance from said pole piece;

armature connection means for slidably connecting said armature plate means with respect to said housing so that said armature plate means may slide reciprocably between a first location whereat said armature plate means contacts said pole piece to a second location whereat said armature plate means is at said first predetermined distance from said pole piece;

spring take-up plate means resiliently connected with said armature plate means;

armature spring means for resiliently connecting said spring take-up plate means to said armature plate means, said armature spring means having a first end and a second end, said first end of said armature spring means being connected with said armature plate means, said second end of said armature spring means being slidably connected with said spring take-up plate means;

thrust plate means having second thrust surface means for selectively contacting the second side of the disc stack, said second thrust surface means being selectively locatable within a second predetermined distance from the second side of the disc stack means; and

bearing means for connecting said spring take-up plate means to said thrust plate means and for permitting mutual rotation therebetween;

wherein an excitation current supplied to said electromagnetic coil causes said armature plate means to be magnetically attracted to said pole piece and as a result thereof slide on said armature connection means toward said pole piece until contact therewith has been made whereupon said excitation current is reduced by a predetermined amount which provides sufficient magnetism to keep said armature plate means in contact with said pole piece, and wherein said first predetermined distance is longer than said second predetermined distance;

wherein further, the movement of said armature plate means into contact with said pole piece causes said armature spring means, said spring take-up plate means, said thrust plate means and said bearing means to move with said armature plate means until said second thrust surface means forcibly abuts said second side of said disc stack means, wherein still further, said armature spring means resiliently compresses in order to accommodate the difference between said first and second predetermined distances thereby supplying a predetermined biasing force to said second thrust surface means with respect to the second side of said disc stack means so as to clamp said first and second sets of annular discs between said first thrust surface means and said second thrust surface means to thereby interconnect said first drive shaft means with said second drive shaft means.

10. The clutch unit of claim 9, wherein said armature connection means further comprises means for biasing said armature plate means away from said pole piece when no excitation current is supplied to said electromagnetic coil.

11. The clutch unit of claim 9, wherein said armature spring means comprises:

a plurality of armature spring bolts, each armature spring bolt having a first end and an opposite second end having a head, said spring take-up plate means being slidably connected with said plurality of armature spring bolts;

a plurality of spacers connected with said armature plate means, a respective spacer of said plurality of spacers being connected with each armature bolt at said first end thereof; and

a plurality of armature springs, a respective armature spring of said plurality of armature springs being located on each armature bolt, said spring take-up plate being trapped on said plurality of armature bolts between said head thereof and said respective armature spring.

12. The clutch unit of claim 11, wherein said armature connection means further comprises means for biasing said armature plate means away from said pole piece when no excitation current is supplied to said electromagnetic coil.

13. The clutch unit of claim 9, wherein said disc stack means further comprises alignment pin means connected with said second set of annular discs for capturing each annular disc of said second set of annular discs and for capturing each annular disc of said first set of annular discs.

14. The clutch unit of claim 13, wherein said alignment pin means comprises:

a plurality of alignment pins, each alignment pin of said plurality of alignment pins having an alignment pin head at a first end thereof and a threaded opposite end;

a plurality of nuts, a nut of said plurality of nuts being threadably engaged on said threaded opposite end of each said alignment pin; and

a plurality of wave washers, wherein each annular disc of said second set of annular discs is separated from each adjacent annular disc of said second set of annular discs by a respective set of wave washers, one wave washer of said respective set of wave washers being carried on each said alignment pin of said plurality of alignment pins;

wherein each annular disc of said second set of annular discs is provided with a plurality of alignment pin holes, an alignment pin of said plurality of alignment pins extending through each alignment pin hole of said plurality of alignment pin holes, said first and second sets of annular discs being captured between said alignment pin head and said nut of each said alignment pin.

15. A brake unit comprising:

a housing;

drive shaft means rotatably connected with said housing;

disc stack means having a first side and a second side, said disc stack means comprising;

a first set of annular discs connected with said drive shaft means so as to be rotatable therewith and axially slidable with respect thereto; and

a second set of annular discs connected with said housing so as to be nonrotatable therewith and axially slidable with respect thereto, said first set of annular discs being interleaved with said second set of annular discs;

first thrust surface means connected with said housing adjacent said first side of said disc stack means;

an electromagnetic coil assembly located within and connected to said housing, said electromagnetic coil assembly comprising an electromagnetic coil and a pole piece, said pole piece being located with respect to said electromagnetic coil so as to be magnetizable thereby; and

an armature assembly located within said housing, said armature assembly comprising;

armature plate means selectively locatable within a first predetermined distance from said pole piece;

armature connection means for slidably connecting said armature plate means with respect to said housing so that said armature plate means may slide reciprocably between a first location whereat said armature plate means contacts said pole piece to a second location whereat said armature plate means is at said first predetermined distance from said pole piece;

spring take-up plate means resiliently connected with said armature plate means;

armature spring means for resiliently connecting said spring take-up plate means to said armature plate means, said armature spring means having a first end and a second end, said first end of said armature spring means being connected with said armature plate means, said second end of said armature spring means being slidably connected with said spring take-up plate means; and

second thrust surface means for selectively contacting said second side of said disc stack means, said second thrust surface means being connected with said spring take-up plate means, said second thrust surface means being selectively locatable within a second predetermined distance from said second side of said disc stack means;

wherein an excitation current supplied to said electromagnetic coil causes said armature plate means to be magnetically attracted to said pole piece and as a result thereof slide on said armature connection means toward said pole piece until contact therewith has been made whereupon said excitation current is reduced by a predetermined amount which provides sufficient magnetism to keep said armature plate means in contact with said pole piece, and wherein said first predetermined distance is longer than said second predetermined distance;

wherein further, the movement of said armature plate means into contact with said pole piece causes said armature spring means, said spring take-up plate means and said second thrust surface means to move with said armature plate means until said second thrust surface means forcibly abuts said second side of said disc stack means, wherein still further, said armature spring means resiliently compresses in order to accommodate the difference between said first and second predetermined distances thereby supplying a predetermined biasing force to said second thrust surface means with respect to the second side of said disc stack means so as to clamp said first and second sets of annular discs between said first thrust surface means and said second thrust surface means to thereby brake said drive shaft means with respect to said housing.

16. The brake unit of claim 15, wherein said armature connection means further comprises means for biasing said armature plate means away from said pole piece when no excitation current is supplied to said electromagnetic coil.

17. The brake unit of claim 15, wherein said armature spring means comprises:

a plurality of armature spring bolts, each armature spring bolt having a first end and an opposite second end having a head, said spring take-up plate means being slidably connected with said plurality of armature spring bolts;

a plurality of spacers connected with said armature plate means, a respective spacer of said plurality of spacers being connected with each armature bolt at said first end thereof; and

a plurality of armature springs, a respective armature spring of said plurality of armature springs being located on each armature bolt, said spring take-up plate being trapped on said plurality of armature bolts between said head thereof and said respective armature spring.

18. The brake unit of claim 17, wherein said armature connection means further comprises means for biasing said armature plate means away from said pole piece when no excitation current is supplied to said electromagnetic coil.

19. The brake unit of claim 15, wherein said disc stack means further comprises alignment pin means connected with said second set of annular discs for capturing each annular disc of said second set of annular discs and for capturing each annular disc of said first set of annular discs.

20. The brake unit of claim 19, wherein said alignment pin means comprises:

a plurality of alignment pins, each alignment pin of said plurality of alignment pins having an alignment pin head at a first end thereof and a threaded opposite end;

a plurality of nuts, a nut of said plurality of nuts being threadably engaged on said threaded opposite end of each said alignment pin; and

a plurality of wave washers, wherein each annular disc of said second set of annular discs is separated from each adjacent annular disc of said second set of annular discs by a respective set of wave washers, one wave washer of said respective set of wave washers being carried on each said alignment pin of said plurality of alignment pins;

wherein each annular disc of said second set of annular discs is provided with a plurality of alignment pin holes, an alignment pin of said plurality of alignment pins extending through each alignment pin hole of said plurality of alignment pin holes, said first and second sets of annular discs being captured between said alignment pin head and said nut of each said alignment pin.

21. A clutch/brake unit comprising:

a housing;

first drive shaft means rotatably connected with said housing;

second drive shaft means rotatably connected with said housing;

first disc stack means having a first side and a second side, said first disc stack means comprising;

a first set of annular discs connected with said first drive shaft means so as to be rotatable therewith and axially slidable with respect thereto; and

a second set of annular discs connected with said second drive shaft means so as to be rotatable therewith and axially slidable with respect thereto, said first set of annular discs being interleaved with said second set of annular discs;

first thrust surface means connected with said second drive shaft means adjacent said first side of said first disc stack means;

second disc stack means having a first side and a second side, said second disc stack means comprising;

a third set of annular discs connected with said first drive shaft means so as to be rotatable therewith and axially slidable with respect thereto; and

a fourth set of annular discs connected with said housing so as to be nonrotatable therewith and axially slidable with respect thereto, said set of third set of annular discs being interleaved with said fourth set of annular discs;

second thrust surface means connected with said housing adjacent said first side of said second disc stack means;

an electromagnetic coil assembly located within and connected to said housing, said electromagnetic coil assembly comprising an electromagnetic coil and a pole piece, said pole piece being located with respect to said electromagnetic coil so as to be magnetizable thereby; and

an armature assembly located within said housing, said armature assembly comprising;

armature plate means selectively locatable within a first predetermined distance from said pole piece;

third thrust surface means connected with said armature plate means for selectively contacting said second side of said second disc stack means when said armature plate means is at said first predetermined distance from said pole piece;

armature connection means for slidably connecting said armature plate means with respect to said housing so that said armature plate means may slide reciprocably between a first location whereat said armature plate means contacts said pole piece to a second location whereat said armature plate means is at said first predetermined distance from said pole piece;

spring take-up plate means resiliently connected with said armature plate means;

armature spring means for resiliently connecting said spring take-up plate means to said armature plate means, said armature spring means having a first end and a second end, said first end of said armature spring means being connected with said armature plate means, said second end of said armature spring means being slidably connected with said spring take-up plate means;

armature bias means for biasing said armature plate means away from said pole piece and toward said second disc stack means so that said third thrust surface means contacts said second side of said second disc stack means at said first predetermined distance from said pole piece when no excitation current is supplied to said electromagnetic coil;

thrust plate means having fourth thrust surface means for selectively contacting the second side of said first disc stack means, said fourth thrust surface means being selectively locatable within a second predetermined distance from said second side of said first disc stack means; and

bearing means for connecting said spring take-up plate means to said thrust plate means and for permitting mutual rotation therebetween;

wherein said armature bias means biases said armature plate means so that said third thrust surface means forces against said second side of said second disc stack means causing said second disc stack means to be clamped between said third thrust surface means and fourth thrust surface means thereby braking said first drive shaft means with respect to said housing; and

wherein an excitation current supplied to said electromagnetic coil causes said armature plate means to be magnetically attracted to said pole piece and as a result thereof slide on said armature connection means toward said pole piece until contact therewith has been made whereupon said excitation current is reduced by a predetermined amount which provides sufficient magnetism to keep said armature plate means in contact with said pole piece, and wherein said first predetermined distance is longer than said second predetermined distance;

wherein further, the movement of said armature plate means into contact with said pole piece causes said armature spring means, said spring take-up plate means, said thrust plate means and said bearing means to move with said armature plate means until said fourth thrust surface means forcibly abuts said second side of said first disc stack means, wherein still further, said armature spring means resiliently compresses in order to accommodate the difference between said first and second predetermined distances thereby supplying a predetermined biasing force to said fouth thrust surface means with respect to the second side of said first disc stack means so as to clamp said first and second sets of annular discs between said first thrust surface means and said fourth thrust surface means to thereby interconnect said first drive shaft means with said second drive shaft means, wherein further said movement of said armature means into contact with said pole piece effects to release said first drive shaft means from being braked with respect to said housing.

22. The clutch/brake unit of claim 21, wherein said armature spring means comprises:

a plurality of armature spring bolts, each armature spring bolt having a first end and an opposite second end having a head, said spring take-up plate means being slidably connected with said plurality of armature spring bolts;

a plurality of spacers connected with said armature plate means, a respective spacer of said plurality of spacers being connected with each armature bolt at said first end thereof; and

a plurality of armature springs, a respective armature spring of said plurality of armature springs being located on each armature bolt, said spring take-up plate being trapped on said plurality of armature bolts between said head thereof and said respective armature spring.

23. The clutch/brake unit of claim 21, wherein said first disc stack means further comprises alignment pin means connected with said second set of annular discs for capturing each annular disc of said second set of annular discs and for capturing each annular disc of said first set of annular discs.

24. The clutch/brake unit of claim 23, wherein said alignment pin means comprises:

a plurality of alignment pins, each alignment pin of said plurality of alignment pins having an alignment pin head at a first end thereof and a threaded opposite end;

a plurality of nuts, a nut of said plurality of nuts being threadably engaged on said threaded opposite end of each said alignment pin; and

a plurality of wave washers, wherein each annular disc of said second set of annular discs is separated from each adjacent annular disc of said second set of annular discs by a respective set of wave washers, one wave washer of said respective set of wave washers being carried on each said alignment pin of said plurality of alignment pins;

wherein each annular disc of said second set of annular discs is provided with a plurality of alignment pin holes, an alignment pin of said plurality of alignment pins extending through each alignment pin hole of said plurality of alignment pin holes, said first and second sets of annular discs being captured between said alignment pin head and said nut of each said alignment pin.

25. The clutch/brake unit of claim 24, wherein said second disc stack means is structured substantially as is said first disc stack means.

26. A clutch/brake unit comprising:

a housing;

first drive shaft means rotatably connected with said housing;

second drive shaft means rotatably connected with said housing;

first disc stack means having a first side and a second side, said first disc stack means comprising;

a first set of annular discs connected with said first drive shaft means so as to be rotatable therewith and axially slidable with respect thereto; and

a second set of annular discs connected with said second drive shaft means so as to be rotatable therewith and axially slidable with respect thereto, said first set of annular discs being interleaved with said second set of annular discs;

first thrust surface means connected with said second drive shaft means adjacent said first side of said first disc stack means;

second disc stack means having a first side and a second side, said second disc stack means comprising;

a third set of annular discs connected with said first drive shaft means so as to be rotatable therewith and axially slidable with respect thereto; and

a fourth set of annular discs connected with said housing so as to be nonrotatable therewith and axially slidable with respect thereto, said set of third set of annular discs being interleaved with said fourth set of annular discs;

second thrust surface means connected with said housing adjacent said first side of said second disc stack means;

a first electromagnetic coil assembly located within and connected to said housing, said first electromagnetic coil assembly comprising a first electromagnetic coil and a first pole piece, said first pole piece being located with respect to said first electromagnetic coil so as to be magnetizable thereby;

a clutch armature assembly located within said housing, said clutch armature assembly comprising;

clutch armature plate means selectively locatable within a first predetermined distance from said first pole piece;

clutch armature connection means for slidably connecting said clutch armature plate means with respect to said housing so that said clutch armature plate means may slide reciprocably between a first location whereat said clutch armature plate means contacts said first pole piece to a second location whereat said clutch armature plate means is at said first predetermined distance from said first pole piece;

spring take-up plate means resiliently connected with said clutch armature plate means;

armature spring means for resiliently connecting said spring take-up plate means to said clutch armature plate means, said armature spring means having a first end and a second end, said first end of said armature spring means being connected with said clutch armature plate means, said second end of said armature spring means being slidably connected with said spring take-up plate means;

thrust plate means having third thrust surface means for selectively contacting the second side of said first disc stack means, said third thrust surface means being selectively locatable within a second predetermined distance from said second side of said first disc stack means; and

bearing means for connecting said spring take-up plate means to said thrust plate means and for permitting mutual rotation therebetween;

a second electromagnetic coil assembly located within and connected to said housing, said second electromagnetic coil assembly comprising a second electromagnetic coil and a second pole piece, said second pole piece being located with respect to said second electromagnetic coil so as to be magnetizable thereby;

a brake armature assembly located within said housing, said brake armature assembly comprising;

brake armature plate means selectively locatable within a third predetermined distance from said second pole piece;

brake armature connection means for slidably connecting said brake armature plate means with respect to said housing so that said brake armature plate means may slide reciprocably between a third location whereat said brake armature plate means contacts said second pole piece to a fourth location whereat said brake armature plate means is at said third predetermined distance from said second pole piece;

fourth thrust surface means connected with said brake armature plate means for selectively contacting said second side of said second disc stack means when said brake armature means is located at said third predetermined distance from said second pole piece; and

brake armature bias means for biasing said brake armature plate means away from said second pole piece and toward said second disc stack means so that said fourth thrust surface selectively contacts said second side of said second disc stack means when no excitation current is supplied to said second electromagnetic coil;

wherein said brake armature bias means biases said brake armature plate means so that said fourth thrust surface means forces against said second side of said second disc stack means causing said second disc stack means to be clamped between said second thrust surface means and said fourth thrust surface means thereby braking said first drive shaft means with respect to said housing, and wherein a first excitation current supplied to said second electromagnetic coil causes said brake armature plate means to be magnetically attracted to said second pole piece and as a result thereof slide on said brake armature connection means toward said second pole piece until contact therewith has been made whereupon said first excitation current is reduced by a first predetermined amount which provides sufficient magnetism to keep said brake armature plate means in contact with said second pole piece;

wherein further a second excitation current supplied to said first electromagnetic coil causes said clutch aramture plate means to be magnetically attracted to said first pole piece and as a result thereof slide on said clutch armature connection means into contact with said first pole piece until contact therewith has been made whereupon said second excitation current is reduced by a second predetermined amount which provides sufficient magnetism to keep said clutch armature plate means in contact with said first pole piece, and wherein said first predetermined distance is longer than said second predetermined distance;

wherein further, the movement of said clutch armature plate means into contact with said first pole piece causes said armature spring means, said spring take-up plate means, said thrust plate means and said bearing means to move with said clutch armature plate means until said third thrust surface means forcibly abuts said second side of said first disc stack means, wherein still further, said armature spring means resiliently compresses in order to accommodate the difference between said first and second predetermined distances thereby supplying a predetermined biasing force to said third thrust surface means with respect to the second side of said first disc stack means so as to clamp said first and second sets of annular discs between said first thrust surface means and said third thrust surface means to thereby interconnect said first drive shaft means with said second drive shaft means.

27. The clutch/brake unit of claim 26, wherein said clutch armature connection means further comprises means for biasing said clutch armature plate means away from said first pole piece when no excitation current is supplied to said first electromagnetic coil.

28. The clutch/brake unit of claim 26, wherein said armature spring means comprises:

a plurality of armature spring bolts, each armature spring bolt having a first end and an opposite second end having a head, said spring take-up plate means being slidably connected with said plurality of armature spring bolts;

a plurality of spacers connected with said clutch armature plate means, a respective spacer of said plurality of spacers being connected with each armature bolt at said first end thereof; and

a plurality of armature springs, a respective armature spring of said plurality of armature springs being located on each armature bolt, said spring take-up plate being trapped on said plurality of armature bolts between said head thereof and said respective armature spring.

29. The clutch/brake unit of claim 28, wherein said clutch armature connection means further comprises means for biasing said clutch armature plate means away from said first pole piece when no excitation current is supplied to said first electromagnetic coil.

30. The clutch/brake unit of claim 26, wherein said first disc stack means further comprises alignment pin means connected with said second set of annular discs for capturing each annular disc of said second set of annular discs and for capturing each annular disc of said first set of annular discs.

31. The clutch/brake unit of claim 30, wherein said alignment pin means comprises:

a plurality of alignment pins, each alignment pin of said plurality of alignment pins having an alignment pin head at a first end thereof and a threaded opposite end;

a plurality of nuts, a nut of said plurality of nuts being threadably engaged on said threaded opposite end of each said alignment pin; and

a plurality of wave washers, wherein each annular disc of said second set of annular discs is separated from each adjacent annular disc of said second set of annular discs by a respective set of wave washers, one wave washer of said respective set of wave washers being carried on each said alignment pin of said plurality of alignment pins;

wherein each annular disc of said second set of annular discs is provided with a plurality of alignment pin holes, an alignment pin of said plurality of alignment pins extending through each alignment pin hole of said plurality of alignment pin holes, said first and second sets of annular discs being captured between said alignment pin head and said nut of each said alignment pin.

32. The clutch/brake unit of claim 31, wherein said second disc stack means is structured substantially as is said first disc stack means.

33. A two-speed drive unit comprising:

a housing;

first drive shaft means rotatably connected with said housing;

second drive shaft means rotatably connected with said housing;

third drive shaft means rotatably connected with said housing;

first disc stack means having a first side and a second side, said first disc stack means comprising;

a first set of annular discs connected with said first drive shaft means so as to be rotatable therewith and axially slidable with respect thereto; and

a second set of annular discs connected with said second drive shaft means so as to be rotatable therewith and axially slidable with respect thereto, said first set of annular discs being interleaved with said second set of annular discs;

first thrust surface means connected with said second drive shaft means adjacent said first side of said first disc stack means;

second disc stack means having a first side and a second side, said second disc stack means comprising;

a third set of annular discs connected with said first drive shaft means so as to be rotatable therewith and axially slidable with respect thereto; and

a fourth set of annular discs connected with said third drive shaft means so as to be rotatable therewith and axially slidable with respect thereto, said set of third set of annular discs being interleaved with said fourth set of annular discs;

second thrust surface means connected with said third drive shaft means adjacent said first side of said second disc stack means;

a first electromagnetic coil assembly located within and connected to said housing, said first electromagnetic coil assembly comprising a first electromagnetic coil and a first pole piece, said first pole piece being located with respect to said first electromagnetic coil so as to be magnetizable thereby; and

a clutch armature assembly located within said housing, said clutch armature assembly comprising;

clutch armature plate means selectively locatable within a first predetermined distance from said first pole piece;

third thrust surface means connected with said clutch armature plate means for selectively contacting said second side of said second disc stack means when said clutch armature plate is at said first predetermined distance from said first pole piece;

clutch armature connection means for slidably connecting said clutch armature plate means with respect to said housing so that said clutch armature plate means may slide reciprocably between a first location whereat said clutch armature plate means contacts said first pole piece to a second location whereat said clutch armature plate means is at said first predetermined distance from said first pole piece;

spring take-up plate means resiliently connected with said clutch armature plate means;

armature spring means for resiliently connecting said spring take-up plate means to said clutch armature plate means, said armature spring means having a first end and a second end, said first end of said armature spring means being connected with said clutch armature plate means, said second end of said armature spring means being slidably connected with said spring take-up plate means;

clutch armature bias means for biasing said clutch armature plate means away from said first pole piece and toward said second disc stack means so that said third thrust surface means selectively contacts said second side of said second disc stack means when no excitation current is supplied to said first electromagnetic coil;

thrust plate means having fourth thrust surface means for selectively contacting the second side of said first disc stack means, said fourth thrust surface means being selectively locatable within a second predetermined distance from said second side of said first disc stack means; and

bearing means for connecting said spring take-up plate means to said thrust plate means and for permitting mutual rotation therebetween;

third disc stack means having a first side and a second side, said third disc stack means comprising;

a fifth set of annular discs connected with said third drive shaft means so as to be rotatable therewith and axially slidable with respect thereto; and

a sixth set of annular discs connected with said housing so as to be nonrotatable therewith and axially slidable with respect thereto, said set of fifth set of annular discs being interleaved with said sixth set of annular discs;

fifth thrust surface means connected with said housing adjacent said first side of said third disc stack means;

a second electromagnetic coil assembly located within and connected to said housing, said second electromagnetic coil assembly comprising a second electromagnetic coil and a second pole piece, said second pole piece being located with respect to said second electromagnetic coil so as to be magnetizable thereby; and

a brake armature assembly located within said housing, said brake armature assembly comprising;

brake armature plate means selectively locatable within a third predetermined distance from said second pole piece;

brake armature connection means for slidably connecting said brake armature plate means with respect to said housing so that said brake armature plate means may slide reciprocably between a third location whereat said brake armature plate means contacts said second pole piece to a fourth location whereat said brake armature plate means is at said third predetermined distance from said second pole piece;

sixth thrust surface means connected with said brake armature plate means for selectively contacting said second side of said third disc stack means when said brake armature plate means is at said third predetermined distance from said second pole piece; and

brake armature bias means for biasing said brake armature plate means away from said second pole piece and toward said third disc stack means so that said sixth thrust surface means selectively contacts said second side of said disc stack means when no excitation current is supplied to said second electromagnetic coil;

wherein said brake armature bias means biases said brake armature plate means so that said sixth thrust surface means forces against said second side of said third disc stack means causing said third disc stack means to be clamped between said fifth thrust surface means and said sixth thrust surface means thereby braking said third drive shaft means with respect to said housing, and wherein a first excitation current supplied to said second electromagnetic coil causes said brake armature plate means to be magnetically attracted to said second pole piece and as a result thereof slide on said brake armature connection means toward said second pole piece until contact therewith has been made whereupon said first excitation current is reduced by a first predetermined amount which provides sufficient magnetism to keep said brake armature plate means in contact with said second pole piece, said movement of said brake armature means into contact with said second pole piece releasing said third drive shaft means from being braked with respect to said housing;

further wherein said clutch armature bias means biases said clutch armature plate means so that said fourth thrust surface means forces against said second side of said second disc stack means causing said second disc stack means to be clamped between said second thrust surface means and said fourth thrust surface means thereby connecting said first drive shaft means with respect to said third drive shaft means; and

wherein further a second excitation current supplied to said first electromagnetic coil causes said clutch armature plate means to be magnetically attracted to said first pole piece and as a result thereof slide on said clutch armature connection means toward said first pole piece until contact therewith has been made whereupon said second excitation current is reduced by a predetermined amount which provides sufficient magnetism to keep said clutch armature plate means in contact with said first pole piece, and wherein said first predetermined distance is longer than said second predetermined distance;

wherein further, the movement of said armature plate means into contact with said first pole piece causes said armature spring means, said spring take-up plate means, said thrust plate means and said bearing means to move with said clutch armature plate means until said third thrust surface means forcibly abuts said second side of said first disc stack means, wherein still further, said armature spring means resiliently compresses in order to accommodate the difference between said first and second predetermined distances thereby supplying a predetermined biasing force to said third thrust surface means with respect to the second side of said first disc stack means so as to clamp said first and second sets of annular discs between said first thrust surface means and said third thrust surface means to thereby interconnect said first drive shaft means with said second drive shaft means.

34. The two-speed drive unit of claim 33, wherein said armature spring means comprises:

a plurality of armature spring bolts, each armature spring bolt having a first end and an opposite second end having a head, said spring take-up plate means being slidably connected with said plurality of armature spring bolts;

a plurality of spacers connected with said armature plate means, a respective spacer of said plurality of spacers being connected with each armature bolt at said first end thereof; and

a plurality of armature springs, a respective armature spring of said plurality of armature springs being located on each armature bolt, said spring take-up plate being trapped on said plurality of armature bolts between said head thereof and said respective armature spring.

35. The two-speed drive unit of claim 33, wherein said first disc stack means further comprises alignment pin means connected with said second set of annular discs for capturing each annular disc of said second set of annular discs and for capturing each annular disc of said first set of annular discs.

36. The two-speed drive unit of claim 35, wherein said alignment pin means comprises:

a plurality of alignment pins, each alignment pin of said plurality of alignment pins having an alignment pin head at a first end thereof and a threaded opposite end;

a plurality of nuts, a nut of said plurality of nuts being threadably engaged on said threaded opposite end of each said alignment pin; and

a plurality of wave washers, wherein each annular disc of said second set of annular discs is separated from each adjacent annular disc of said second set of annular discs by a respective set of wave washers, one wave washer of said respective set of wave washers being carried on each said alignment pin of said plurality of alignment pins;

wherein each annular disc of said second set of annular discs is provided with a plurality of alignment pin holes, an alignment pin of said plurality of alignment pins extending through each alignment pin hole of said plurality of alignment pin holes, said first and second sets of annular discs being captured between said alignment pin head and said nut of each said alignment pin.

37. The two-speed drive unit of claim 36, wherein each of said second and third disc stack means are structured substantially as is said first disc stack means.

38. A two-speed drive unit comprising:

a housing;

first drive shaft means rotatably connected with said housing;

second drive shaft means rotatably connected with said housing;

third drive shaft means rotatably connected with said housing;

first disc stack means having a first side and a second side, said first disc stack means comprising;

a first set of annular discs connected with said first drive shaft means so as to be rotatable therewith and axially slidable with respect thereto; and

a second set of annular discs connected with said second drive shaft means so as to be rotatable therewith and axially slidable with respect thereto, said first set of annular discs being interleaved with said second set of annular discs;

first thrust surface means connected with said second drive shaft means adjacent said first side of said first disc stack means;

second disc stack means having a first side and a second side, said second disc stack means comprising;

a third set of annular discs connected with said first drive shaft means so as to be rotatable therewith and axially slidable with respect thereto; and

a fourth set of annular discs connected with said housing so as to be nonrotatable therewith and axially slidable with respect thereto, said set of third set of annular discs being interleaved with said fourth set of annular discs;

third disc stack means having a first side and a second side, said third disc stack means comprising;

a fifth set of annular discs connected with said first drive shaft means so as to be rotatable therewith and axially slidable with respect thereto; and

a sixth set of annular discs connected with said third drive shaft means so as to be rotatable therewith and axially slidable with respect thereto, said fifth set of annular discs being interleaved with said sixth set of annular discs;

second thrust surface means connected with said third drive shaft means adjacent said first side of said third disc stack means;

a first electromagnetic coil assembly located within and connected to said housing, said first electromagnetic coil assembly comprising a first electromagnetic coil and a first pole piece, said first pole piece being located with respect to said first electromagnetic coil so as to be magnetizable thereby;

a first armature assembly located within said housing, said first armature assembly comprising;

first armature plate means selectively locatable within a first predetermined distance from said first pole piece;

third thrust surface means connected with said first armature plate means for selectively contacting said first side of said second disc stack means when said first armature plate means is at said first predetermined distance from said first pole piece;

first armature connection means for slidably connecting said first armature plate means with respect to said housing so that said first armature plate means may slide reciprocably between a first location whereat said first armature plate means contacts said first pole piece to a second location whereat said first armature plate means is at said first predetermined distance from said first pole piece;

first spring take-up plate means resiliently connected with said first armature plate means;

first armature spring means for resiliently connecting said first spring take-up plate means to said first armature plate means, said first armature spring means having a first end and a second end, said first end of said first armature spring means being connected with said first armature plate means, said second end of said first armature spring means being slidably connected with said first spring take-up plate means;

first armature bias means for biasing said first armature plate means away from said first pole piece and toward said second disc stack means so that said third thrust surface means selectively contacts said first side of said second disc stack means when no excitation current is supplied to said first electromagnetic coil;

first thrust plate means having fourth thrust surface means for selectively contacting the second side of said first disc stack means, said fourth thrust surface means being selectively locatable within a second predetermined distance from said second side of said first disc stack means; and

first bearing means for connecting said first spring take-up plate means to said first thrust plate means and for permitting mutual rotation therebetween;

a second electromagnetic coil assembly located within and connected to said housing, said second electromagnetic coil assembly comprising a second electromagnetic coil and a second pole piece, said second pole piece being located with respect to said second electromagnetic coil so as to be magnetizable thereby; and

a second armature assembly located within said housing, said second armature assembly comprising;

second armature plate means selectively locatable within a third predetermined distance from said second pole piece;

fifth thrust surface means connected with said second armature plate means for selectively contacting said second side of said second disc stack means when said second armature plate means is at said third predetermined distance from said second pole piece;

second armature connection means for slidably connecting said second armature plate means with respect to said housing so that said second armature plate means may slide reciprocably between a third location whereat said second armature plate means contacts said second pole piece to a fourth location whereat said second armature plate means is at said third predetermined distance from said second pole piece;

second spring take-up plate means resiliently connected with said second armature plate means;

second armature spring means for resiliently connecting said second spring take-up plate means to said second armature plate means, said second armature spring means having a first end and a second end, said first end of said second armature spring means being connected with said second armature plate means, said second end of said second armature spring means being slidably connected with said second spring take-up plate means;

second armature bias means for biasing said second armature plate means away from said second pole piece and toward said second disc stack means so that said fifth thrust surface selectively contacts said second side of said second disc stack means when no excitation current is supplied to said second electromagnetic coil;

second thrust plate means having a sixth thrust surface means for selectively contacting the second side of said third disc stack means, said sixth thrust surface means being selectively locatable within a fourth predetermined distance from said second side of said third disc stack means; and

second bearing means for connecting said second spring take-up plate means to said second thrust plate means and for permitting mutual rotation therebetween;

wherein said first and second armature bias means bias respectively each of said first and second armature plate means so that said third thrust surface means and said fifth thrust surface means force respectively against said first and second sides of said second disc stack means causing said second disc stack means to be clamped between said third thrust surface means and said fifth thrust surface means thereby braking said first drive shaft means with respect to said housing;

wherein further a first excitation current supplied to said first electromagnetic coil causes said first armature plate means to be magnetically attracted to said first pole piece and as a result thereof slide on said first armature connection means toward said first pole piece until contact therewith has been made whereupon said first excitation current is reduced by a first predetermined amount which provides sufficient magnetism to keep said first armature plate means in contact with said first pole piece, and wherein said first predetermined distance is longer than said second predetermined distance;

wherein further, the movement of said first armature plate means into contact with said first pole piece causes said first armature spring means, said first spring take-up plate means, said first thrust plate means and said first bearing means to move with said first armature plate means until said fourth thrust surface means forcibly abuts said second side of said first disc stack means, wherein, said first armature spring means resiliently compresses in order to accommodate the difference between said first and second predetermined distances thereby supplying a first predetermined biasing force to said fourth thrust surface means with respect to the second side of said first disc stack means so as to clamp said first and second sets of annular discs between said first thrust surface means and said fourth thrust surface means to thereby interconnect said first drive shaft means with said second drive shaft means;

wherein further a second excitation current supplied to said second electromagnetic coil causes said second armature plate means to be magnetically attracted to said second pole piece and as a result thereof slide on said second armature connection means toward said second pole piece until contact therewith has been made whereupon said second excitation current is reduced by a second predetermined amount which provides sufficient magnetism to keep said second armature plate means in contact with said second pole piece, and wherein said third predetermined distance is longer than said fourth predetermined distance;

wherein further, the movement of said second armature plate means into contact with said second pole piece causes said second armature spring means, said second spring take-up plate means, said second thrust plate means and said second bearing means to move with said second armature plate means until said sixth thrust surface means forcibly abuts said second side of said second disc stack means, wherein, said second armature spring means resiliently compresses in order to accommodate the difference between said third and fourth predetermined distances thereby supplying a second predetermined biasing force to said sixth thrust surface means with respect to the second side of said second disc stack means so as to clamp said third and fourth sets of annular discs between said fifth thrust surface means and said sixth thrust surface means to thereby interconnect said first drive shaft means with said third drive shaft means.

39. The two-speed drive unit of claim 38, wherein said armature spring means comprises:

a plurality of armature spring bolts, each armature spring bolt having a first end and an opposite second end having a head, said spring take-up plate means being slidably connected with said plurality of armature spring bolts;

a plurality of spacers connected with said armature plate means, a respective spacer of said plurality of spacers being connected with each armature bolt at said first end thereof; and

a plurality of armature springs, a respective armature spring of said plurality of armature springs being located on each armature bolt, said spring take-up plate being trapped on said plurality of armature bolts between said head thereof and said respective armature spring.

40. The two-speed drive unit of claim 38, wherein said first disc stack means further comprises alignment pin means connected with said second set of annular discs for capturing each annular disc of said second set of annular discs and for capturing each annular disc of said first set of annular discs.

41. The two-speed drive unit of claim 40, wherein said alignment pin means comprises:

a plurality of alignment pins, each alignment pin of said plurality of alignment pins having an alignment pin head at a first end thereof and a threaded opposite end;

a plurality of nuts, a nut of said plurality of nuts being threadably engaged on said threaded opposite end of each said alignment pin; and

a plurality of wave washers, wherein each annular disc of said second set of annular discs is separated from each adjacent annular disc of said second set of annular discs by a respective set of wave washers, one wave washer of said respective set of wave washers being carried on each said alignment pin of said plurality of alignment pins;

wherein each annular disc of said second set of annular discs is provided with a plurality of alignment pin holes, an alignment pin of said plurality of alignment pins extending through each alignment pin hole of said plurality of alignment pin holes, said first and second sets of annular discs being captured between said alignment pin head and said nut of each said alignment pin.

42. The two-speed drive unit of claim 41, wherein said second and third disc stack means are structured substantially as is said first disc stack means.