CHAIN TENSIONING DEVICE

• US 3,802,286 A
• Filed: 02/26/1973
• Issued: 04/09/1974
• Est. Priority Date: 03/16/1972
• Status: Expired due to Term

• Current Assignee: Adam Biedermann, Gerhard Winklhofer, Hermann Zollner
• Original Assignee: Adam Biedermann, Gerhard Winklhofer, Hermann Zollner
• Inventors: Winklhofer, Gerhard, Zollner, Hermann, Biedermann, Adam
• Primary Examiner(s): Gerin, Leonard H.
• Application Number:
  US05/335,458
• Time in Patent Office: 407 Days
• Field of Search: 74/242.11S,242.13A
• US Class Current: 474/111
• CPC Class Codes: F16H 2007/0806 Compression coil springs
• CPC Class Codes: F16H 2007/0812 Fluid pressure
• CPC Class Codes: F16H 2007/0857 Screw mechanisms
• CPC Class Codes: F16H 2007/0859 Check valves
• CPC Class Codes: F16H 2007/0872 Sliding members
• CPC Class Codes: F16H 2007/0891 Linear path
• CPC Class Codes: F16H 7/08 Means for varying tension of belts, ropes, or chains pulleys of adjustable construction F16H55/52 ; gearings with endless belts F16H7/02; tensioning for chains or belts specially adapted for cycles B62M9/16; belt or chain tensioning arrangements for endless conveyors B65G23/44
• CPC Class Codes: F16H 7/0829 with vibration damping means
• CPC Class Codes: F16H 7/0836 of the fluid and restriction type, e.g. dashpot

Abstract

A chain tensioning device in which a plunger axially movable in a cylinder carries a chain engaging head and is biased outward of the cylinder cavity by a compression spring. One of two guide elements engaging each other for threaded movement substantially about the cylinder axis is secured to the plunger while the other guide element is fixedly fastened to one part of a unidirectional ratchet coupling, the other coupling part being fastened to the cylinder. The engaged coupling permits the plunger and chain engaging head to move outward of the cylinder cavity while preventing movement of the plunger toward a retracted position. An operating shaft is accessible outside the cavity for manual disengagement of the ratchet coupling and rotation of the second guide element to move the plunger into its retracted position against the compression spring. A manually releasable locking device locks the plunger in the retracted position.

Claims

1. A tensioning device for an elongated, flexible, power transmitting element comprising, in combination:

a. a cylinder member having an axis and defining a cavity therein;

b. mounting means for mounting said member on a stationary support;

c. a plunger member received in said cylinder member for axial movement inward of said cavity into a retracted position, and outward of said cavity away from said retracted position;

d. an engaging head mounted on said plunger member outside said cavity for joint axial movement with said plunger member;

e. yieldably resilient means interposed between said members and biasing said plunger member away from said retracted position thereof;

f. a first guide element secured to said plunger member;

g. a second guide element rotatable in said cavity about said axis and engaging said first guide element for relative helical movement of said guide elements, whereby said second guide element is rotated about said axis in one direction during said outward movement of said plunger member;

h. ratchet means on said second guide element for limiting inward movement of said plunger member under axial pressure applied to said head to a substantially constant maximum distance in all axial positions of said plunger member spaced from said retracted position;

i. operating means outside said cavity for manually turning said second guide element in a direction opposite to said one direction and for thereby moving said plunger member into said retracted position thereof; and

j. manually releasable locking means for locking said plunger member in said retracted position against axially outward movement.

2. A device as set forth in claim 1, wherein said ratchet means include a uni-directional coupling engageable to secure said second guide element to said cylinder member against relative angular movement in said opposite direction while permitting said angular movement in said one direction.

3. A device as set forth in claim 2, wherein said operating means include a shaft member extending axially outward of said cavity in a direction away from said head, said shaft member being fixedly fastened to said second guide elemeNt.

4. A device as set forth in claim 3, wherein said cylinder member has an end wall transverse to said axis, said shaft member passing axially and rotatably through said end wall, and abutment means limiting axial movement of said shaft member relative to said cylinder member to a distance sufficient for disengaging said coupling.

5. A device as set forth in claim 4, wherein the portion of said shaft member outside said cylinder is formed with a key-receiving recess.

6. A device as set forth in claim 3, wherein said locking means include a resilient arm projecting from said shaft member radially relative to said axis, and abutment means on said cylinder member engaging said arm and thereby limiting angular movement of said second guide element under the force of said yieldably resilient means, said arm being sufficiently resilient to permit deflection of the same when said shaft member is being turned manually.

7. A device as set forth in claim 3, wherein said second guide element is formed with a helical, elongated groove, and said first guide element engages said groove for longitudinal movement therein, a portion of said second guide element bounding a laterally enlarged pocket communicating with one longitudinally terminal portion of said groove, said portion of said second guide element jointly with said first guide element constituting said locking means, said first guide element being received in said pocket when said plunger member is locked in said retracted position, and being released from said pocket by movement of said shaft member axially inward of said cavity.

8. A device as set forth in claim 2, wherein said locking means include a locking member, said cylinder member and said head constituting a pair of cooperating elements, said locking member being mounted on one of said cooperating elements, essentially consisting of reslient material, and lockingly engaging the other cooperating element under the resilient force thereof in said retracted position of said plunger member.

9. A device as set forth in claim 2, wherein said head, said plunger member, and said one guide element jointly constitute a plunger assembly, and said locking means are operatively interposed between said assembly and said cylinder member for releasably locking said plunger member in said retracted position.

10. A device as set forth in claim 2, wherein said locking means include a locking member mounted on said cylinder member and resiliently engaging said second guide element for impeding movement thereof relative to said cylinder member.

11. A device as set forth in claim 2, wherein said plunger member has a central bore and is formed with an elongated, helical, first groove about said axis radially open toward said bore, wall portions of said plunger member bounding said groove and constituting said first guide element, said second guide element being tubular about said axis and carrying at least one radial projection received in said groove, additional wall portions of said plunger member bounding an elongated second groove extending in a radial plane relative to said axis, respective longitudinally terminal portions of said first and second grooves communicating with each other for sequential longitudinal movement of said projection in said first and second grooves, said additional wall portions in cooperation with said projection constituting said locking means.

12. A device as set forth in claim 1, wherein said second guide element is formed with a helical, elongated groove, and said first guide element engages said groove for longitudinal movement therein, respective edge portions of said second guide element laterally bounding said groove, said ratchet means including a plurality of ratchet teeth on the edge portion bounding said groove in an axial direction away from said head, said ratchet teeth projecting into said groove and being spaced in the direction of groove elongation for receiving said first guide element therebetween during said inward Movement of said plunger member under said axial pressure.