Combined hydrostatic and mechanical transmission

Claim 2

A hydro-mechanical drive comprising: an engine driven input shaft driven at a substantially constant speed; a hydrostatic drive unit including a variable displacement, reversible pump connected to and driven by the input shaft and a fixed displacement motor hydraulically driven by the pump at infinitely variable speeds within a limited range in either direction; a planetary gear train including a ring gear operatively connected to and driven by the input shaft, a sun gear operatively connected to and driven by the motor, and a planetary pinion means constantly meshing with the ring and sun gears and carried by a carrier, so that the speed and direction of rotation of the motor affects the speed of the carrier to provide infinitely variable speed characteristics in the carrier within a limited range; a planetary output shaft; means connecting the carrier to the planetary output shaft; and a shiftable step ratio transmission having a least three different gear ratios and having an input shaft driven by the planetary output shaft to provide at least three speed ranges with infinitely variable speed characteristics.

Claim 3

The invention defined in claim 1 wherein the means connecting the carrier to the planetary output shaft includes a clutch means selectively engageable and disengageable to respectively connect or disconnect the carrier from the planetary output shaft.

Claim 4

The invention defined in claim 2 wherein the ring gear is connected to the input shaft through an axially extending sleeve member, the carrier includes an annular portion coaxially disposed within the sleeve member, and the planetary output shaft includes an annular portion coaxially disposed within the annular carrier portion, the clutch means including a plurality of clutch discs alternately connected to the annular portions of the carrier and the planetary output shaft and means for selectively compressing the adjacent clutch disc into engagement.

Claim 5

The invention defined in claim 2 and including a brake means operatively associated with the planetary output shaft and the clutch means for stopping rotation of said shaft when the clutch means is disengaged.

Claim 6

The invention defined in claim 4 wherein the clutch means includes a hydraulic motor means operative to engage the clutch means in response to fluid pressure supplied thereto, and the brake means includes a spring means biasing the brake means toward an engaged condition and a hydraulic motor means operative to shift the brake means into a disengaged condition against said spring bias in response to fluid pressure supplied thereto, and a hydraulic connecting means operatively connecting the brake and clutch hydraulic motor means to supply fluid pressure to the brake means and disengage the brake means when fluid pressure is supplied to the clutch means.

Claim 7

The invention defined in claim 1 wherein the planetary output shaft is coaxially journaled relative to the input shaft and the step-ratio transmission input shaft is coaxially connected to and driven by the planetary output shaft.

Claim 8

The invention defined in claim 1 wherein the step ratio transmission includes at least four different gear ratios, to provide at least four different ranges with infinitely variable speeds, the highest speeds of the three lowest ranges overlapping the next highest range to provide infinitely variable output speeds from the lowest speed in the lowest range to the highest speed in the fourth range.

Claim 9

The invention defined in claim 1 wherein the motor is driven at infinitely variable speeds between 0 and a predetermined speed in either direction and is operatively connected to the planetary gear train to infinitely vary the speed of the planetary output shaft within an approximate 2:1 ratio.

Claim 10

The invention defined in claim 1 wherein the hydraulic pump and motor are coaxially aligned and are parallel and adjacent to the planetary gear train.

Claim 11

A hydro-mechanical drive comprising: an engine driven input shaft driven at a substantially constant speed; an input gear means coaxially connected to and driven by the input shaft; a planetary gear train including a planetary output shaft coaxially journaled relative to the input shaft, a sun gear journaled on the output shaft, a ring gear including an axially extending sleeve portion connected to and driven by the input gear, planetary pinion gear means constantly meshing with the ring and the sun gears and carried by an annular carrier element journaled on the output shaft and disposed within the sleeve portion of the ring gear; an annular element coaxially connected to the output shaft and coaxially disposed within the carrier element; a hydraulically actuated clutch means engageable and disengageable to respectively connect the carrier element to and disconnect the carrier element from said annular element on the output shaft and including a plurality of annular clutch discs alternately connected to the carrier element and said annular element and compressible into an engagement by an annular piston coaxially disposed within an annular cylinder formed in the carrier element; a hydrostatic drive unit including a variable displacement hydraulic pump connected to and driven by the input gear and a hydraulic motor hydraulically driven by the pump at infinitely variable speeds within a limited range and drivingly connected to the sun gear; and a shiftable step ratio transmission having a plurality of different gear ratios and including an input shaft coaxially connected to and driven by the planetary output shaft to provide a plurality of speed ranges with infinitely variable speed characteristics.

Claim 12

A hydro-mechanical drive comprising: an engine driven input shaft driven at a substantially constant speed; an input gear means coaxially connected to and driven by the input shaft; a planetary gear train including a planetary output shaft coaxially journaled relative to the input shaft, a sun gear journaled on the output shaft, a ring gear including an axially extending sleeve portion connected to and driven by the input gear, planetary pinion gear means constantly meshing with the ring and the sun gears and carried by an annular carrier element journaled on the output shaft and disposed within the sleeve portion of the ring gear; an annular element coaxially connected to the output shaft and coaxially disposed within the carrier element; a hydraulically actuated clutch means engageable and disengageable to respectively connect the carrier element to and disconnect the carrier element from said annular element on the output shaft and including a plurality of annular clutch discs alternately connected to the carrier element and said annular element and compressible into an engagement by an annular piston coaxially disposed within an annular cylinder formed in the carrier element; a hydrostatic drive unit including a variable displacement hydraulic pump connected to and driven by the input gear and a hydraulic motor hydraulically driven by the pump at infinitely variable speeds within a limited range and drivingly connected to the sun gear; and a shiftable step ratio transmission having a plurality of different gear ratios and including an input shaft coaxially connected to and driven by the planetary output shaft to provide a plurality of speed ranges with infinitely variable speed characteristics.

Claim 13

The invention defined in claim 10 and including a hydraulically actuated brake means operatively connected to the planetary output shafT for stopping said shaft when engaged, said brake means being biased toward an engaged condition and shiftable into a disengaged condition in response to fluid pressure supplied thereto, and also including means connecting the brake means to the clutch means for automatically supplying fluid pressure to the brake means when fluid pressure is supplied to the clutch means.

Claim 14

A hydro-mechanical drive comprising: an input shaft; a hydrostatic drive unit including a variable displacement pump connected to and driven by the input shaft and a hydraulic motor driven by the pump at infinitely variable speeds within a limited range; a differential gear train including a first element operatively connected to and driven by the input shaft, a second element operatively connected to and driven by the hydraulic motor, a third element, a plurality of pinion gear means carried by the one of said elements and constantly meshing with the other two; a differential gearing output shaft; a hydraulically actuatable clutch means operative between the third element and the output shaft to selectively connect said element to the output shaft in response to fluid pressure supplied to the clutch means; a shiftable step ratio transmission having an input shaft operatively connected to and driven by the output shaft and selectively shiftable into a plurality of different conditions to provide a plurality of different gear ratios; and a brake means operatively connected to said step ratio transmission input shaft for stopping said shaft when engaged, said brake means being biased toward its engaged position and hydraulically shifted into a disengaged position in response to fluid pressure supplied thereto; and means operatively connecting the brake means to the clutch means for automatically supplying fluid pressure to the brake means when it is supplied to the clutch means.

Claim 15

A hydro-mechanical drive comprising: an input shaft; a hydrostatic drive unit including a variable displacement pump connected to and driven by the input shaft and a hydraulic motor driven by the pump at infinitely variable speeds within a limited range; a differential gear train including a first element operatively connected to and driven by the input shaft, a second element operatively connected to and driven by the hydraulic motor, a third element, a plurality of pinion gear means carried by the one of said elements and constantly meshing with the other two; a differential gearing output shaft; a hydraulically actuatable clutch means operative between the third element and the output shaft to selectively connect said element to the output shaft in response to fluid pressure supplied to the clutch means; a shiftable step ratio transmission having an input shaft operatively connected to and driven by the output shaft and selectively shiftable into a plurality of different conditions to provide a plurality of different gear ratios; and a brake means operatively connected to said step ratio transmission input shaft for stopping said shaft when engaged, said brake means being biased toward its engaged position and hydraulically shifted into a disengaged position in response to fluid pressure supplied thereto; and means operatively connecting the brake means to the clutch means for automatically supplying fluid pressure to the brake means when it is supplied to the clutch means.

Claim 16

The invention defined in claim 12 wherein the brake means is biased toward an engaged position by a brake spring means and the clutch is biased toward its disengaged position by the clutch spring means, the fluid pressure supplied to the brake means and the clutch means fully shifting the brake means to its disengaged position before the clutch means is fully engaged.

Claim 17

A hydro-mechanical drive comprising: an engine driven input shaft driven at approximately a constant speed; a hydrostatic drive unit including a variable displacement reversible pump connected to and driven by the input shaft and a fixed displacement motor hydraulically driven by the pump at infinitely variable speeds within a limited range in either direction; a differential gear train including a first element operatively connected to and driven by the input shaft, a second element operatively connected to and driven by the motor, a third element, a planetary pinion means carried by one of said elements and constantly meshing with the other two, a differential gearing output shaft, and means operatively connecting the third element to said output shaft; and a shiftable step ratio transmission having an input shaft coaxially connected to and driven by the differential gearing output shaft, a counter shaft, and an output shaft parallel to the counter shaft and the input shaft, and a plurality of spur gears on said shafts, and shiftable means operatively associated with the gears in the shafts and shiftable into different positions to establish the four different drive paths through said gear means and shafts to provide at least four different gear ratios and consequently four different speed ranges, the input shaft being driven at infinitely variable speeds within a limited range by said differential gearing output shaft to provide infinitely variable speed characteristics within each of said four ranges.

Claim 18

A hydro-mechanical drive comprising: an engine driven input shaft driven at approximately a constant speed; a hydrostatic drive unit including a variable displacement reversible pump connected to and driven by the input shaft and a fixed displacement motor hydraulically driven by the pump at infinitely variable speeds within a limited range in either direction; a differential gear train including a first element operatively connected to and driven by the input shaft, a second element operatively connected to and driven by the motor, a third element, a planetary pinion means carried by one of said elements and constantly meshing with the other two, a differential gearing output shaft, and means operatively connecting the third element to said output shaft; and a shiftable step ratio transmission having an input shaft coaxially connected to and driven by the differential gearing output shaft, a counter shaft, and an output shaft parallel to the counter shaft and the input shaft, and a plurality of spur gears on said shafts, and shiftable means operatively associated with the gears in the shafts and shiftable into different positions to establish the four different drive paths through said gear means and shafts to provide at least four different gear ratios and consequently four different speed ranges, the input shaft being driven at infinitely variable speeds within a limited range by said differential gearing output shaft to provide infinitely variable speed characteristics within each of said four ranges.

Claim 19

The invention defined in claim 14 wherein the hydraulic motor is driven at infinitely variable speeds between zero and a predetermined speed in either direction and is operatively connected to the differential gear train to infinitely vary the speeD of the differential gearing output shaft within an approximate 2:1 ratio, the highest speeds of the three lowest ranges overlapping the low speed of the next highest range to permit infinitely variable output speeds from the lowest speed in the lowest range to the highest speed in the fourth range.