Multispeed powershift transmission

• US 6,190,280 B1
• Filed: 09/16/1999
• Issued: 02/20/2001
• Est. Priority Date: 01/16/1998
• Status: Expired due to Fees

• Current Assignee: Joachim Horsch
• Original Assignee: Joachim Horsch
• Inventors: Horsch, Joachim
• Primary Examiner(s): Wright, Dirk
• Application Number:
  US09/381,554
• Time in Patent Office: 523 Days
• Field of Search: 475/209, 475/218
• US Class Current: 475/209
• CPC Class Codes: F16H 37/042 change gear transmissions in group arrangement
• CPC Class Codes: F16H 47/04 the mechanical gearing being of the type with members having orbital motion
• CPC Class Codes: F16H 61/70 specially adapted for change-speed gearing in group arrangement, i.e. with separate change-speed gear trains arranged in series, e.g. range or overdrive-type gearing arrangements

Abstract

A mechanical power transmission system for an engine or motor driven vehicle is disclosed. The transmission of the present invention includes an input transmission, a compound planetary transmission, and an output transmission. The compound planetary transmission includes two input and two outputs. The input transmission has a single input connected to the engine or motor of the vehicle and two outputs connected to the two inputs to the planetary transmission. The output transmission includes two inputs connected to the two outputs of the planetary transmission and one output connected through suitable gearing to the wheels of the vehicle or any other mechanism to be driven by a motoring device at various speed ratios.

Claims

1. A mechanical power transmission system connectable to an engine driven output of an apparatus, comprising:

a housing;

an input transmission arranged within said housing and including an input and two outputs, with said input being operably connected to the driven output of said apparatus;

a compound planetary system including two inputs and two outputs, with said inputs being operably connected to the two outputs of said input transmission through mating gear sets; and

an output transmission including two inputs connected to the two outputs of the compound planetary system and one output connected, through gearing, to a mechanism configured to be driven by said motor driven apparatus at various speeds.

2. The mechanical transmission system according to claim 1 wherein said input transmission absorbs engine power through said input shaft and divides the engine power selectively at various proportions for delivery to said two outputs, with said outputs of said input transmission delivering power at certain proportions to said two inputs of said compound planetary system, with the compound planetary system being configured to absorb, combine, and deliver power through either of the two compound planetary system outputs to said output transmission, and with said output transmission being configured to absorb power selectively at various gear ratios established through gearing and transmitting power to said one output at a variety of rotational speeds relative to the rotational speed of the engine output, and wherein the power flow at the outputs of said planetary system may be positive or negative.

3. The mechanical transmission system according to claim 1 wherein said input transmission is selectively conditionable to transmit the engine power selectively at various gear ratios to either the first output with the second output stopped, or transmit the engine power to the second output with the first output stopped, with either of said outputs delivering power to said compound planetary system, and with the mating gear sets of said compound planetary system absorbing power from said input transmission through either a first input or a second input and transmitting the power to either of said two outputs, with said two outputs of said compound planetary system being operably connected to deliver power to said output transmission, with said output transmission having selectively operable various power flow paths to for permitting said output of said output transmission to be operated at a variety of rotational speeds relative to the rotational speed of the engine output, and wherein the power flow at the output of said output transmission may be positive or negative.

4. The mechanical transmission system according to claim 1 wherein said compound planetary system is configured to absorb power through either of said two inputs connected to said input transmission and divide the power at certain ratios for delivery to said two outputs operably connected to the two inputs of the output transmission, and wherein said output transmission absorbs power at certain ratios transmitted thereto from said compound planetary system and combines the power for selective delivery at various gear ratios to a rotational output thereby providing said output of said output transmission with a variety of rotational speeds relative to the rotational speed of the engine output, and wherein the power flow of said rotational output of said output transmission may be positive or negative.

5. The transmission system of claim 1, in which the compound planetary system is comprised of first and second planet systems, each planet system having a ring gear, a sun gear and planet gears which are rotatably supported by shafts anchored in planet carriers, with the first planet system being a simple planetary, where each planet gear is in mesh with the sun gear and with the ring gear, and with the second planet system being a double planetary including a first set of planet gears in mesh with the sun gear and with a second set of planet gears in mesh with the ring gear, and wherein the ring gear of the first planet system is connected to the ring gear of the second planet system, and wherein the planet carrier of the first planet system is connected to the planet carrier of the second planet system, with the ring gear and the sun gear of the first planet system being the two inputs of the compound planetary system and the carrier and the sun gear of the second planet system being the two outputs of the compound planetary system.

6. The transmission system of claim 1, in which the compound planetary system is comprised of first and second planet systems, with the first planet system having a ring gear, and both planet systems having a sun gear and planet gears which are rotatably supported by shafts anchored in a planet carrier, with the first planet system being a simple planetary, where each planet gear is in mesh with the sun gear and the ring gear, and with the second planet system being a double planetary, where a first set of planets is in mesh with the sun gear and a second set of planets, the second set of planets of the second planet system being connected to the planet gears of the first planet system in pairs and rotatably mounted on the same shafts which are anchored in the common carrier, with the ring gear and the sun gear of the first planet system being the two inputs of the compound planetary system, and with the carrier and the sun gear of the second planet system being the two outputs of the compound planetary system.

7. The transmission system of claim 1, in which the compound planetary system is comprised of first and second planet systems, each planet system having a ring gear, a sun gear and planet gears which are rotatably supported by shafts anchored in planet carriers, with the first and second planet system being simple planetaries, where each planet gear is in mesh with the sun gear and with the ring gear, respectively, where the ring gear of the first planet system is connected to the planet carrier of the second planet system, and with the planet carrier of the first planet system being connected to the ring gear of the second planet system, and wherein the ring gear and the sun gear of the first planet system comprise the two inputs of the compound planetary system and the ring gear and the sun gear of the second planet system comprise the two outputs of the compound planetary system.

8. The transmission system of claim 1, in which the compound planetary system is comprised of first and second planet systems, with each planet system having a ring gear, a sun gear and planet gears which are rotatably supported by shafts anchored in planet carriers, and wherein said first and second planet systems are each configured as double planetary systems where a first set of planets is in mesh with the sun gear and a second set of planets is in mesh with the ring gear, where the ring gear of the first planet system is connected to the ring gear of the second planet system and where the planet carrier of the first planet system is connected to the sun gear of the second planet system, with the ring gear and the sun gear of the first planet system being the two inputs of the compound planetary system and the carrier and the sun gear of the second planet system being the two outputs of the compound planetary system.

9. The transmission system of claim 1, in which the compound planetary system is comprised of first and second planet systems, with each planet system having a ring gear, a sun gear and planet gears which are rotatably supported by shafts anchored in planet carriers, and wherein the first and second planet systems are configured as simple planetaries, where each planet gear is in mesh with the sun gear and with the ring gear, respectively, and wherein the ring gear of the first planet system is connected to the ring gear of the second planet system and the sun gear of the first planet system is connected to the sun gear of the second planet system, and wherein the ring gear and the sun gear of the first planet system comprise the two inputs of the compound planetary system and the ring gear and the sun gear of the second planet system comprise the two outputs of the compound planetary system.

10. The transmission system of claim 1, in which the compound planetary system is comprised of first and second planet systems, with each planet system having a ring gear, a sun gear and planet gears which are rotatably supported by shafts anchored in planet carriers, with the first planet system being a simple planetary, where each planet gear is in mesh with the sun gear and with the ring gear, and with the second planet system being a double planetary, where a first set of planets is in mesh with the sun gear and a second set of planets is in mesh with the ring gear, where the ring gear of the first planet system is connected to the planet carrier of the second planet system, and where the planet carrier of the first planet system is connected to the sun gear of the second planet system, with the ring gear and the sun gear of the first planet system comprising the two inputs of the compound planetary system and the ring gear and the sun gear of the second planet system comprising the two outputs of the compound planetary system.

11. The transmission system of claim 1, in which the compound planetary system is comprised of first and second planet systems, with each planet system having a ring gear, a sun gear and planet gears which are rotatably supported by shafts anchored in planet carriers, and wherein the first planet system is a simple planetary, where each planet gear is in mesh with the sun gear and with the ring gear, and wherein the second planet system is a double planetary, where one set of planets is in mesh with the sun gear and the other set of planets is in mesh with the ring gear, and wherein the ring gear of the first planet system is connected to the sun gear of the second planet system, and where the planet carrier of the first planet system is connected to the ring gear of the second planet system, and where the planet carrier and the sun gear of the first planet system comprise the two inputs of the compound planetary system and the carrier and the sun gear of the second planet system comprise the two outputs of the compound planetary system.

12. The transmission system of claim 1, in which the compound planetary system is comprised of first and second planet systems, with each planet system having a ring gear, a sun gear and planet gears which are rotatably supported by shafts anchored in planet carriers, with the first and second planet system being configured as simple planetaries, where each planet gear is in mesh with the sun gear and with the ring gear, respectively, and wherein the planet carrier of the first planet system is connected to the ring gear of the second planet system, and wherein the sun gear of the first planet system is connected to the sun gear of the second planet system, and wherein the planet carrier and the sun gear of the first planet system comprise the two inputs of the compound planetary system and the planet carrier of the second planet system and the ring gear of the second plant system comprise the two outputs of the compound planetary system.

13. The transmission system of claim 1, in which the compound planetary system is comprised of first and second planet systems, with each planet system having a ring gear, a sun gear and planet gears which are rotatably supported by shafts anchored in planet carriers, and wherein the first and second planet systems are configured as simple planetaries, where each planet gear is in mesh with the sun gear and with the ring gear respectively, and where the sun gear of the first planet system is connected to the sun gear of the second planet system, and where the planet carrier of the first planet system is connected to the planet carrier of the second planet system, and wherein the ring gear and the sun gear of the first planet system comprise the two inputs of the compound planetary system and the ring gear and the planet carrier of the second planet system comprise the two outputs of the compound planetary system.

14. The transmission system of claim 1, in which the compound planetary system is comprised of first and second planet systems, with each planet system having a ring gear, a sun gear and planet gears which are rotatably supported by shafts anchored in planet carriers, and wherein the first planet system is a simple planetary, where each planet gear is in mesh with the sun gear and with the ring gear, and wherein the second planet system is a double planetary where a first set of planets is in mesh with the sun gear and with a second set of planets is in mesh with the ring gear, where the carrier of the first planet system is connected to the carrier of the second planet system, and where the sun gear of the first planet system is connected to the ring gear of the second planet system, and wherein the ring gear and the sun gear of the first planet system comprise the two inputs of the compound planetary system and the carrier and the sun gear of the second planet system comprise the two outputs of the compound planetary system.

15. The transmission system of claim 1, in which the input transmission includes first, second and third clutches, with said first clutch being selectively engagable to connect the first input of the compound planetary system to one input of said input transmission to establish a forward speed ratio, and with said third clutch being selectively engagable to connect the first input of the planetary system to the input of the input transmission to establish a reverse speed ratio, with said forward speed ratio being essentially equal to said reverse speed ratio, and wherein said second clutch is selectively engagable to connect said first input of the compound planetary system to the housing thereby stopping rotation of said first input member to the compound planetary system, and wherein said input transmission further comprises an odd number N_s of clutches selectively engagable to connect the second input member of the compound planetary system to the input of said input transmission at a number (N_s−

1)/2 of speed ratios in forward and at the same number (N_s−

1)/2 of speeds in reverse at essentially equal ratios as the forward speeds, said input transmission further including another selectively engagable clutch to releasably connect the second input of the compound planetary system to the housing thereby stopping rotation of said second input of the compound planetary system, and wherein said second input of the compound planetary system is that input whose speed is varied to effect a change in output speed of the transmission system within a normal operating range, said normal operating range being that range of selectable speeds in which said first input of the compound planetary system remains at constant speed with respect to speed of the engine whenever a sequential shift is made.

16. The transmission system of claim 1, in which the input transmission includes a forward clutch, with said forward clutch being selectively engagable to operably connect one input of the compound planetary system to the input of said input transmission at a predetermined forward speed ratio, with said input transmission further including an even number N_s of clutches selectively engagable to connect the second input of the compound planetary system to the input of said input transmission at a number (N_s)/2 of speed ratios in a forward direction, and wherein said second input of the compound planetary system is that input whose speed is varied to effect a change in output speed of the transmission system within a normal operating range, said normal operating range being that range of selectable speeds in which said one input of the compound planetary system remains at constant speed with respect to the speed of the engine whenever a sequential shift is made.

17. The transmission system of claim 16 wherein said input transmission further includes a selectively engagable stopping clutch which, when engaged, operably connects said one input of the compound planetary system to the housing thereby stopping rotation of said one input member of the compound planetary system.

18. The transmission system of claim 16 wherein said input transmission further includes a selectively engagable reverse clutch which, when engaged, operably connects said one input of the compound planetary system to the input of the input transmission to establish a reverse speed ratio which is substantially equivalent to said forward speed ratio established when said forward clutch is selectively engaged, with said input transmission further including an even number of clutches selectively engagable to connect a second input of the compound planetary system to the input of said input transmission at a number (N₈)/2 of speed ratios in a reverse direction and at essentially equal ratios in the forward speeds.

19. The transmission system of claim 1, in which the output transmission is comprised of first and second sets of clutches selectively engagable to operate the output of said output transmission at predetermined ratios relative to the outputs of the compound planetary system, with said first set of output transmission clutches operably connecting said output of said output transmission to a first output of the compound planetary system at various gear ratios, and wherein the second set of output transmission clutches operably connecting said output of said output transmission to the second output of the compound planetary system at various gear ratios, said first output of the compound planetary system being that member which increases in speed as a second input of the compound planetary system increases in speed while the first input of the compound planetary system remains at constant speed, and said second output of the compound planetary system being that member which decreases in speed as said second input of the compound planetary system increases in speed while said first input of the compound planetary system remains at a relatively constant speed.

20. The transmission system of claim 19 wherein each set of clutches in the output transmission is provided with a predetermined number of clutches, and wherein the number of predetermined clutches in one set of said sets of clutches is one fewer than in the other set of said sets of clutches.

21. The transmission system of claim 3, in which all gear ratios of the mating gear sets within the compound planetary system are such that a change in speed of one output of the compound planetary system with respect to the speed of the second input of the compound planetary system multiplied by r₂ is essentially equal to a change in speed of the second output of the compound planetary system with respect to the speed of the second input of the compound planetary system multiplied by −

r₁, with the first input of the compound planetary system at constant speed as expressed in the following differential equation $r_2<br><br>\frac{<br><br>{\mathrm{<br><br>}}_1}{<br><br>{\mathrm{<br><br>}}_1}=-K<br><br>\text{\hspace{1em}<br><br>}<br><br>r_1<br><br>\frac{<br><br>\mathrm{ℯ<br><br>}}{<br><br>{\mathrm{<br><br>}}_1},$

R=constant,

and are such that the speed of the second output of the compound planetary system multiplied by r₂ is essentially equal to the speed of the first output of the compound planetary system multiplied by r₁ multiplied by K, with the second input at zero speed and the first input of the compound planetary system at constant speed, as expressed in the following equation;

where S₂r₂=KCr₁ at S₁=0,

S₂ is the speed of the second output of the compound planetary system which decreases in speed as the second input of the compound planetary system increases in speed while the first input of the compound planetary system is at constant speed,

r₂ is the lowest selectable gear ratio between the sun gear and the output of the output transmission,

C is the speed of the first output of the compound planetary system which increases in speed as the second input of the compound planetary system increases in speed while the first input of the compound planetary system remains at constant speed,

r₁ is the lowest selectable gear ratio between the carrier of the compound planetary system and the output of the output transmission,

S₁ is the speed of the second input of the compound planetary system, which is selectively connectable to the output of said engine at one or more ratios in forward and reverse, with said second input of the compound planetary system being that input whose speed is varied to effect a change in output speed of the transmission system within a normal operating range, said normal operating range being that range of selectable speeds in which the said first input of the compound planetary system remains at constant speed with respect to the engine,

R is the speed of the first input of the compound planetary system, which remains selectively connected to the engine at a certain gear ratio either in forward or in reverse, whenever the transmission is operating in the normal operating range either in forward or reverse respectively, and where

K is a constant calculated by the following equation;

$K=\left(\frac{H}{L}\right)<br><br>\exp <br><br>\left(\frac{1}{N_0-2+\frac{2<br><br>\mathrm{Ns}}{\mathrm{Ns}+1}}\right),$

 

where

H is the highest desired rated output speed of the transmission system,

L is the lowest desired rated output speed to be attained in the normal operating range said normal operating range being the range of selectable speeds in which the first input of the compound planetary system remains connected through a gear ratio to the engine,

N₀ is the number clutches in the output transmission,

N_s is the number of clutches in the gear set which selectively connects the engine through gear ratios to second input of the compound planetary system or stops said second input of said compound planetary system from rotation.

22. The transmission system of claim 19, wherein said input transmission has an odd number of selectable connections between the input of said input transmission and the second input of the compound planetary system, with each selectable connection establishing a gear ratio, and wherein the gear ratio of each selectable connection, including the one where the second input of the compound planetary system is stopped, is such that geometric steps in the output speed of the transmission system from one gear selection to the next in a certain interval are essentially equal, said interval being defined as the range from a gear selection in which two clutches in the output transmission are engaged, to that higher gear selection in which the second input of the compound planetary system is stopped, with a geometric step being defined as the factor with which an output speed of one gear selection is multiplied to obtain the speed of the next higher gear selection, and with said second input being that input of the compound planetary system whose speed is varied in order to effect a change in output speed of the transmission system within a normal operating range, said normal operating range being that range of selectable gears in which the first input of the compound planetary system remains at constant speed with respect to the engine driven output.

23. The transmission system of claim 19, wherein said input transmission has an even number of selectable connections between the input of said input transmission and the second input of the compound planetary system, with each selectable connection establishing a gear ratio, and wherein the gear ratio of each selectable connection is such that geometric steps in the output speed of the transmission system from one gear selection to the next in a certain interval are essentially equal, said interval being defined as the range from a gear selection in which two clutches in the output transmission are engaged, to that higher gear selection in which the direction of the speed of the second input of the compound planetary system is changed, with a geometric step being defined as the factor with which an output speed of one gear selection is multiplied to obtain the speed of the next higher gear selection, and with said second input being that input member of the compound planetary system whose speed is varied in order to effect a change in output speed of the transmission system within a normal operating range, said normal operating range being that range of selectable gears in which the first input of the compound planetary system remains at a substantially constant speed with respect to the engine driven output either in forward or reverse.

24. The transmission of system of claim 21 wherein each selectively operable flow path of said output transmission is conditionable between a low speed gear ratio and a high speed gear ratio, and wherein adjacent speed gear ratios in each flow path are differentiated by a factor equal to K².

25. The transmission system of claim 24 wherein the lowest speed ratio in one selectively operable flow path of said output transmission is generally equal to the lowest speed ratio in another selectively operable flow path of said output transmission.

26. The transmission system of claim 22 within said normal operating range, in which the speed selection that connects the two outputs of the compound planetary system at two respective ratios (c and s) to the output of the output transmission, provides a speed between the speed of the output of the output transmission when the second input of the compound planetary is connected to the input of the input transmission at a certain ratio (f) and one of said inputs of the compound planetary system is connected at the same ratio (c) to the output of the output transmission and (in between) the speed of the output of the output transmission when the second input of the compound planetary system is connected to the input of the input transmission at the same ratio (f) and said second output of the compound planetary system is connected at the same ratio (s) to the output of the output transmission.

29. The transmission system of claim 22 wherein speed selections are selectively obtainable outside the normal operating range where the first input to the compound planetary system is connected to the input of the input transmission by the engagement of any one output clutch in the output transmission in combination with any one input clutch which connects the second input of the compound planetary system to the input of the input transmission and wherein the first input to the compound planetary system is stopped by the engagement of a clutch.

41. The transmission system of claim 5 wherein each ring gear of the first and second planet systems of the compound planetary system is mounted through a splined carrier to a hollow shaft on a first side, said hollow shaft being mounted through a bearing in the housing thereby allowing a second side to float on the meshing ring gear and planets, with said planets being allowed to float on the meshing interrelationship between the planets and the sun gear, and wherein the output sun gear of the second planet system being mounted on a shaft carried by bearings, and wherein the input sun gear of the first planet system is allowed to float thus insuring equal distribution of tooth load among the planet gears.

42. The transmission of claim 19 in which a shaft is attached to the one of the two outputs of the compound planetary system, and wherein said shaft is mounted in the housing through two axially spaced bearings for carrying the gear load of either one of two gears plus the load of a bearing, said loads being cantilevered off an output side of said shaft, while the sungear of the second planet system is cantilevered off an input side of said shaft.

27. The transmission system of 22 wherein sequentially higher speeds for the output of the output transmission are obtainable within the normal operating range where the first put of the compound planetary system is connected to the input of the input transmission through four selectively engagable clutches, with a lowest speed ratio being established for said transmission system when only one of said four clutches is engaged, and with one additional clutch of said four clutches being engaged in order to obtain the next higher speed for the output of the output transmission.

28. Transmission system of claim 27 wherein speed selections are obtainable through various gear ratios for the output of the output transmission within a specified range and outside the normal operating range, said specified range being selectively obtainable when one input to the compound planetary system is connected to the input of the input transmission through a series of selectively engaged clutches including first and second output clutches and an input clutch, with one gear ratio being obtainable by simultaneous engagement of two output clutches in combination with the input clutch which connects the second input of the compound planetary system to the input of the input transmission, and wherein an additional gear ratio being obtainable when said two output clutches are selectively engaged to connect the output of the compound planetary system to the output of the output transmission, and wherein still another gear ratio is obtainable when one output clutch is selectively operated to connect the other output of the compound planetary system to the output of the output transmission.

30. A transmission system operably connected to a rotatable output of an engine said transmission system comprising:

a housing;

an input transmission arranged within said housing and having an input, two outputs and selectively operable gearing disposed between said input and said outputs to define a first selectively connectable power flow path from the engine to either first or second inputs of a compound planetary system, and wherein said input transmission is comprised of a second selectively connectable power flow path from the engine to the second input of the compound planetary system, with said second selectively connectable power flow path being continuously variable, and wherein said compound planetary system is configured with mating gear sets to absorb, combine and deliver power through either of two outputs to an output transmission, with said output transmission having first and second inputs connected to the two outputs of the compound planetary system to absorb power selectively at various gear ratios and gearing for transmitting power to an output at various rotational speeds relative to the rotational speed of the engine output, and wherein the power flows at the outputs of the planetary system may be positive or negative.

31. The transmission system of claim 30 wherein said continuously variable power flow path comprises a hydrostatic system including a variable displacement hydrostatic unit selectively connectable to the engine output and a fixed displacement hydrostatic unit selectively connectable to the second input of the compound planetary system, with said hydrostatic units being connected by hydraulic conduits.

32. The transmission system of claim 31 wherein said continuously variable power flow path provides a speed range for the second input of the compound planetary system between forward and reverse such that at as an output of said hydrostatic system approaches extreme speeds, in forward or reverse directions, a shift from a first clutch to a second clutch in the output transmission is effected at or near synchronism of the engaging clutch, with synchronism being defined as the condition where an input member of the clutch is operated at approximately equivalent speed as an output member of the same clutch.

33. The transmission system of claim 32 in which the second continuously variable power flow path is configured to allow full available engine power to be transmitted in a normal hydromechanical range but lacks the capacity to transmit full tractive load in a pure hydrostatic range when two lowest speed output clutches in the output transmission are selectively engaged for operation, said normal hydromechanical range being that portion of a selected range where part of the power flows through the hydrostatic system and part of the power flows through the mechanical connection, and wherein said pure hydrostatic range being that portion of the selected range where all the power flows through the hydrostatic system.

34. The transmission system of claim 33 wherein said housing is mountable on a vehicle, and wherein at least one of said lowest speed output clutches in said output transmission is configured sufficiently large to bring the vehicle from standstill to full motion under full tractive load by gradually engaging said sufficiently large output clutch.

35. The transmission system of claim 33 wherein said hydrostatic system within said input transmission has sufficient capacity to bring the vehicle from standstill to full motion under full tractive load by gradually increasing the displacement of the variable hydrostatic unit from zero to maximum forward or reverse in selected gearing where the two lowest speed clutches in the output transmission are engaged, thus allowing engagement of the forward or reverse clutch at synchronism to provide full continuous variability at full load from maximum reverse speed through zero speed to maximum forward speed.

36. The transmission system of claim 30, wherein said input transmission includes a plurality of clutches selectively engagable to connect the input of the compound planetary system to either the engine output or to the housing, said plurality of clutches including a forward ratio clutch, a reverse ratio clutch, and a clutch for releasably maintaining said input from operably moving.

37. The transmission system of claim 30, wherein said input transmission further includes a countershaft along with selectively operable and operationally equivalent forward and reverse pairs of clutches, which said pairs may be physically equal to each other, and wherein said forward pair of clutches are mounted on said input shaft with two forward clutch gears, and wherein said reverse pair of clutches are mounted on the countershaft with two reverse clutch gears, the countershaft being carried within and by the housing, with said selectively operable gearing connecting the input of said input transmission and said countershaft such that one gear connected to a first output of said input transmission outputs is in mesh with one of said forward clutch gears and one of said reverse clutch gears, and wherein another gear connected to a second output of said input transmission is in mesh with another of said forward clutch gears and the other of said reverse clutch gears, and wherein each output of said input transmission is selectively connectable to the housing through two clutches respectively.

38. The transmission system of claim 37 wherein said countershaft extends beyond said housing to provide a selectable connection to said variable displacement hydrostatic unit, and wherein the input of the compound planetary system extends beyond said housing to provide a selectable connection to said fixed displacement hydrostatic unit.

39. The transmission system of claim 30 wherein said input transmission includes a selectively operable first forward single pack clutch arranged on said input to the input transmission for selectively connecting the second input of the compound planetary system to the input of the input transmission a selectively operable second forward single pack clutch pack arranged on said input to the input transmission for selectively connecting the first input of the compound planetary system to said input of said input transmission, and wherein said input transmission further includes first and second reverse clutches located on first and second countershafts carried by said housing, and wherein said gearing of said input transmission includes a first gear mounted to said input shaft and in meshing relationship relative to a second gear, with said first and second gears being mounted on said first and second countershafts, respectively, in addition to being in mesh with a clutch gear of said second forward single pack clutch, and wherein said clutch gear acting as an idler gear for a Power Take Off gear train, and wherein an output gear of said first reverse clutch and an output gear of the said first forward single pack clutch being in mesh with a gear connected to one input of said compound planetary system, said one input of said compound planetary system also being operably connected to an output of a holding clutch selectively operable to inhibit operation of said one input of the compound planetary system, and wherein an output gear of said second reverse clutch is in mesh with a gear mounted on said second input of the compound planetary system, with said second single pack forward clutch having a clutch carrier mounted to said one input of said compound planetary system, with said carrier of said compound planetary system carrying an additional clutch arranged concentric to said second single pack forward clutch F, said additional clutch B selectively connecting said one input of the compound planetary system to the housing thereby stopping operation of the one input to the compound planetary system.

40. The transmission system of claim 39 wherein the second input of the compound planetary system is selectively connectable to said hydrostatic unit through a hollow elongated shaft extending from the second input to the compound planetary system, said hollow shaft serving as one output of the compound planetary system.

43. A transmission system operably connected to a rotatable output of an engine, said transmission system comprising:

a housing;

an input transmission arranged within said housing and having an input, two outputs and selectively operable gearing disposed between said input and said outputs to define a first selectively connectable power flow path from the engine to either first or second inputs of a compound planetary system, and wherein said input transmission includes a hydrostatic system including a variable hydrostatic unit defining, at least partially, a second selectively connectable power flow path from the engine to the second input of the compound planetary system, with said second selectively connectable power flow path being continuously variable, and wherein said compound planetary system is configured with mating gear sets to absorb, combine and deliver power through either of two outputs to an output transmission, with said output transmission having first and second inputs connected to the two outputs of the compound planetary system to absorb power selectively at various gear ratios and gearing for transmitting power to an output at various rotational speeds relative to the rotational speed of the engine output, and wherein continuously variable power flow path provides a speed range for the second input of the compound planetary system between forward and reverse such that as an output of said hydrostatic system approaches extreme speeds, in forward or reverse directions, a shift from a first clutch to a second clutch in the output transmission is effected at or near synchronism of the engaging clutch, with synchronism being defined as the condition where an input member of the clutch is operated at approximately equivalent speed as an output member of the same clutch.

44. The transmission system according to claim 43 wherein said housing is mounted on vehicle.

45. The transmission system of claim 44 wherein said hydrostatic system within said input transmission has sufficient capacity to bring the vehicle from standstill to full motion under full tractive load by gradually increasing the displacement of the variable hydrostatic unit from zero to maximum forward or reverse in selected gearing where two lowest speed clutches in the output transmission are engaged, thus allowing engagement of a forward or a reverse clutch at synchronism to provide full continuous variability at full load from maximum reverse speed through zero speed to maximum forward speed.

46. The transmission system according to claim 43 wherein said input transmission has selectable connections between the inputs to said input transmission and the outputs of said input transmission for permitting said transmission system to operate within a normal operating range, said normal operating range including a range of selectable connections between the inputs to the compound planetary system and the outputs of the input transmission.

47. The transmission system of claim 46 wherein speed selections for the output of the output transmission are selectively obtainable outside of the normal operating range by simultaneous engagement of first and second output clutches arranged within said output transmission in combination with conditioning of the variable hydrostatic unit to connect the second output of the compound planetary system to the input of the input transmission, wherein said first output clutch connects the second output of the compound planetary system to the output of the output transmission, and wherein said second output clutch connects the first output member of the compound planetary system to the output of the output transmission at respective ratios.

48. The transmission system of claim 46 wherein speed selections for the output of the output transmission are selectively obtainable outside of the normal operating range by selective engagement of an output clutch in the output transmission in combination with the variable hydrostatic unit which connects the second output of the compound planetary system to the input of the input transmission and in combination with the first input to the compound planetary system being maintained substantially stationary by a clutch.

49. A transmission system of claim 43, in which gear ratios of the mating gear sets within the compound planetary system are such that the rate of change in speed of one output of the compound planetary system with respect to the speed of the second input of the compound planetary system is essentially equal to the rate of change in speed of the second output of the compound planetary system with respect to the speed of the second input of the compound planetary system multiplied by the number minus (r₁/r₂) multiplied by K, with the first input of the compound planetary system at constant speed as expressed in the following differential equation $r_2$





1



1=-K

 



r1



ℯ





1,

R=constant,

and are such that the speed of the second output of the compound planetary system multiplied by r₂ is essentially equal to the speed of the first output of the compound planetary system multiplied by r₁ multiplied by K, with the second input at zero speed and the first input of the compound planetary system at constant speed, as expressed in the following equation;