Extended range hydraulic transmission

Abstract

.Badd.A power train includes an input means and an output means, the output means being operatively connected with a speed differential gear means. A first drive transmitting means including hydraulic transmission means is connected between the input means and the gear means. A second drive transmitting means is connected between the input means and the gear means, and means is provided for drivingly connecting and disconnecting the second drive transmitting means. The power train can be changed from a single drive path condition to a dual drive path condition and vice versa while maintaining a constant drive ratio between the input means and the output means. .Baddend.

I claim. 1. An extended range hydraulic transmission comprising input means, hydraulic transmission means including a pair of separate hydraulic elements, means providing hydraulic communication between said elements, one of said hydraulic elements being permanently drivingly connected with said input means, output planetary gearing including a plurality of members, the other of said hydraulic elements being permanently drivingly connected with one of the members of said output planetary gearing output means, another member of said output planetary gearing being permanently drivingly connected with said output means, means providing a driving connection between said input means and a third member of said output planetary gearing, said last-mentioned driving connection including selectively engageable and disengageable means for connecting or disconnecting said third member from said input means, fixed means, selectively engageable means for connecting or disconnecting said third member with said fixed means for holding said third member against movement, said hydraulic elements each including drum means having a plurality of pistons reciprocably mounted therewithin, swash plate means for controlling the stroke of said pistons, and a control system operatively connected with each of said selectively engageable and disengageable means for operating said selectively engageable and disengageable means, said control system also being operatively connected with said swash plate means for controlling the movement thereof, said control system including compensating means which operates the swash plate means to adjust the drive ratio through said hydraulic elements in a direction opposite to the drive ratio change effected by said selectively engageable and disengageable means in such a manner as to maintain a constant over-all drive ratio. 2. An extended range hydraulic transmission comprising an input shaft, a hydraulic transmission comprising a pair of hydraulic elements defining a pump and motor arrangement, each of said hydraulic elements being associated with a common hydraulic valve plate structure providing hydraulic intercommunication therebetween for acting as a pump and motor arrangement, each of said hydraulic elements including a drum means having piston means reciprocably mounted therewith, each of said drum means being mounted for rotation about a fixed axis of rotation, one of said hydraulic elements being permanently drivingly interconnected with said input shaft, output planetary gearing comprising a plurality of drivingly connected members, another of said hydraulic elements being drivingly connected with one member of said output planetary gearing, an output shaft, said output shaft being drivingly connected with another member of said output planetary gearing, means providing a driving connection between said input shaft and a third member of said output planetary gearing, said last-mentioned driving connection including a selectively operable clutch means for engaging or disengaging the said third member with respect to said input shaft, fixed means, a selectively engageable, and disengageable brake means for connecting or disconnecting said third member of the output planetary gearing with said fixed means, each of said hydraulic elements including swash plate means for controlling the reciprocation of the piston means thereof, and a control system operatively connected with said swash plate means and with said clutch and brake means for moving the swash plate means and adjusting the angle thereof and for engaging and disengaging the clutch and brake means to provide an extended range of operation, said control system including compensator means which functions to adjust the pump and motor ratio in a direction opposite to the ratio change effected by the clutch or brake means in such a manner as to maintain a constant over-all drive ratio to thereby provide a smooth transition when shifting ranges and to maintain a substantially constant speed and torque output. 3. Apparatus as defined in claim 2 including first control means for controlling the angle of said swash plate means to thereby control the pump and motor ratio, second control means for controlling the engagement and disengagement of said clutch means and said brake means to thereby control the mechanical driving ratio, said compensator means being mechanically interconnected with said first control means, and a hydraulic connection between said compensator means and said second control means for controlling the operation of said compensator means in accordance with shifting movements of said second control means. 4. Apparatus as defined in claim 3 wherein said compensator means includes a cylinder element and a piston element, one of said elements being drivingly connected with the means for controlling movement of said swash plates, and the other of said elements being operatively connected with said first control means, spring means within said cylinder element normally urging said piston element in one direction, said hydraulic connection being connected with said cylinder element so as to urge said piston in a direction contrary to the direction it is urged by said spring means. 5. An extended range hydraulic transmission comprising a casing, an input shaft extending into said casing, an output shaft extending outwardly of said casing, hydraulic transmission means within said casing include a pair of hydraulic elements, each of said elements including drum means, a plurality of pistons reciprocably disposed within each of said drum means, swash plate means associated with the pistons of each hydraulic element for controlling the stroke of the pistons, said hydraulic transmission means including a common hydraulic valve plate structure fixed to said casing and operatively associated with said drum means for providing hydraulic communication therebetween, said input shaft being rotatably journalled at one end thereof within said valve plate structure, one of said drum means being disposed in surrounding relationship to said input shaft and fixed thereto for rotation therewith, an intermediate shaft having one end thereof rotatably journalled within said vale plate structure, the other of said drum means being disposed in surrounding relationship to said intermediate shaft and being fixed for rotation therewith, said input shaft and said intermediate shaft being in alignment with one another, said drum means being disposed at opposite sides of said valve plate structure and in running contact therewith, a second intermediate shaft rotatably journalled within said casing and disposed in spaced parallel relationship with said input shaft and said first-mentioned intermediate shaft, sun gear means disposed at one end of said second intermediate shaft, planet gear means in engagement with said sun gear means and fixed to said output shaft, ring gear means disposed in engagement with said planet gear means, gear means fixed to said first-mentioned intermediate shaft in engagement with said ring gear means, a sleeve member disposed in surrounding relationship to said second intermediate shaft and mounted for rotation with respect thereto, said sleeve member being geared to said input shaft for rotation therewith, selectively engageable and disengageable clutch means for selectively engaging or disengaging said sleeve member to said second intermediate shaft, a fixed sleeve member disposed in surrounding spaced relationship to said second intermediate shaft, selectively engageable and disengageable brake means for connecting said second intermediate shaft to said fixed sleeve member for fixing said second intermediate shaft against rotation, and power operated means for selectively and alternatively operating said clutch and brake means. 6. Apparatus as defined in claim 5 including a control system operatively connected with the swash plates and the selectively operable clutch and brake means of the transmission for controlling the operation thereof, said control system including means for changing the drive ratio through said hydraulic transmission means and for changing the drive ratio through the mechanical drive means including the components associated with said second intermediate shaft, said control system including compensation means for changing the drive ratio through said hydraulic transmission means in a direction opposite to the change in drive ratio effected through said mechanical connection so as to maintain a constant over-all drive ratio whereby the transmission is enabled to make a smooth transition when shifting ranges with substantially no change in output speed or torque output. 7. An extended range hydraulic transmission comprising an input shaft, a hydraulic transmission comprising a pair of hydraulic elements, each of said hydraulic elements including drum means having a plurality of pistons reciprocably mounted therewithin, swash plate means associated with each of said hydraulic elements for controlling the movement of said pistons, said hydraulic transmission means including a common hydraulic valve plate structure, each of said drum means being disposed at one side of said valve plate structure, said valve plate structure providing hydraulic communication between said hydraulic elements, one of said drum means being disposed in surrounding relationship to said input shaft and secured thereto for rotation therewith, an intermediate shaft means, the other of said drum means being disposed in surrounding relationship to said intermediate shaft means and secured thereto for rotation therewith, an output shaft, output planetary gearing including a plurality of members, one of said members being permanently drivingly connected with said output shaft, another of said members being permanently drivingly connected with said intermediate shaft means, means providing a driving connection between said input shaft and a third member of said output planetary gearing, said last-mentioned driving connection including selectively operable clutch means, fixed means, and selectively operable brake means for connecting said third member of the output planetary gearing with said fixed means, said clutch and brake means being disposed at the opposite side of said valve plate structure from said drum means. 8. Apparatus as defined in claim 7 wherein said third member of the output planetary gearing is disposed at one end of a second intermediate shaft means, an intermediate drive member secured for rotation with said second intermediate shaft means, said clutch means being adapted to connect said intermediate drive member with said input shaft, and a second intermediate member disposed in driving engagement with said first-mentioned intermediate member, said second intermediate member being rotatably journalled on said first-mentioned intermediate shaft means, said brake means being adapted to connect said second intermediate member with said fixed means, said first-mentioned intermediate shaft means being rotatably supported within said valve plate structure. 9. Apparatus as defined in claim 8 including a control system operatively connected with the swash plates and the selectively operable clutch and brake means of the transmission for controlling the operation thereof, said control system including means for changing the drive ratio through said hydraulic transmission means and for changing the drive ratio through the mechanical drive means including the components associated with said second intermediate shaft, said control system including compensation means for changing the drive ratio through said hydraulic transmission means in a direction opposite to the change in drive ratio effected through said mechanical connection so as to maintain a constant over-all drive ratio whereby the transmission is enabled to make a smooth transition when shifting ranges with substantially no change in output speed or torque output. 10. An extended range hydraulic transmission comprising an input shaft, hydraulic transmission means comprising a pair of hydraulic elements, each of said hydraulic elements including drum means, a plurality of pistons reciprocably mounted within each of said drum means, swash plates operatively associated with the pistons in each drums means for controlling the movements of said pistons, a common hydraulic valve plate structure interposed between said hydraulic elements, the drum means of said hydraulic elements having a running fit with opposite sides of said valve plate structure, said valve plate structure providing hydraulic communication between said hydraulic elements, one of said drum means being disposed in surrounding relationship to and fixed to said input shaft for rotation therewith, a first intermediate shaft having sun gear means formed at one end thereof, the opposite end thereof being fixed to the other of said drum means for rotation therewith, a second intermediate shaft, planet gear means drivingly engaged with said sun gear means, a selectively engageable and disengageable clutch means for selectively connecting said second intermediate shaft with said planet gear means, ring gear means, an output means, said output means being operatively connected with said ring gear means, fixed means, and a selectively operable brake means for selectively connecting and disconnecting said planet gear means with said fixed means for holding said planet gear means when said brake means is engaged. 11. An extended range hydraulic transmission comprising a casing, an input shaft extending into said casing, hydraulic transmission means comprising a pair of hydraulic elements each of which includes drum means, a plurality of pistons reciprocably mounted within each of said drum means, swash plates operatively associated with the pistons of each drum means for controlling the movement of said pistons, a common hydraulic valve plate structure fixed to said casing and interposed between said drum means, said drum means engaging opposite faces of said valve plate structure, said input shaft being rotatably journalled within said valve plate structure, one of said drum means being disposed in surrounding relationship to and operatively connected with said input shaft for rotation therewith, a first intermediate shaft having one end thereof rotatably journalled within said valve plate structure, the other of said drum means being disposed in surrounding relationship to said first intermediate shaft and operatively connected thereto for rotation therewith, said first intermediate shaft and said drive shaft being aligned with one another, said drum means each being mounted for rotation about a fixed axis which is coincidental with the axis of rotation of said input shaft and said first intermediate shaft, said first intermediate shaft having sun gear means formed at the end thereof, a second intermediate shaft connected with said input shaft for rotation therewith and being disposed within said first intermediate shaft and concentric therewith, planet gear means operatively connected with said sun gear means, a selectively engageable and disengageable clutch for connecting or disconnecting said second intermediate shaft with said planet gear means, ring gear means operatively connected with said planet gear means, output means operatively connected with said ring gear means, fixed means, and a selectively engageable and disengageable brake for connecting said planet gear means with said fixed means. 12. Apparatus as defined in claim 11 including a control system operatively connected with the swash plates and the selectively operable clutch and brake means of the transmission for controlling the operation thereof, said control system including means for changing the drive ratio through said hydraulic transmission means and for changing the drive ratio through the mechanical drive means including the components associated with said second intermediate shaft, said control system including compensation means for changing the drive ratio through said hydraulic transmission means in a direction opposite to the change in drive ratio effected through said mechanical connection so as to maintain a constant overall drive ratio whereby the transmission is enabled to make a smooth transition when shifting ranges with substantially no change in 
     
        output speed or torque output. 13. An extended range hydraulic transmission comprising input means, hydraulic transmission means including a pair of separate hydraulic elements, means providing hydraulic communication between said elements, one of said hydraulic elements being drivingly connected with said input means, output planetary gearing including a plurality of members, the other of said hydraulic elements being drivingly connected with one of the members of said output planetary gearing, output means, another member of said output planetary gearing being drivingly connected with said output means, means providing a driving connection between said input means and a third member of said output planetary gearing, said last-mentioned driving connection including selectively engageable and disengageable means for connecting or disconnecting said third member from said input means, fixed means, and selectively engageable and disengageable means for operatively connecting a fourth member of said planetary gearing with said fixed means for holding said fourth member against movement. 14. Apparatus as defined in claim 13 including power take-off means, and selectively engageable and disengageable means for connecting or disconnecting said power take-off means with said driving connection between said input means and said third member of the output planetary gearing. 15. An extended range hydraulic transmission comprising an input shaft, an output shaft, hydraulic transmission means including a pair of separate hydraulic elements, means providing hydraulic communication between said elements, one of said hydraulic elements being drivingly connected with and in concentric relation to said input shaft, output planetary gearing including a plurality of members, one of said members of said output planetary gearing being drivingly connected with another of said hydraulic elements, said output shaft being drivingly connected with another of said members of the output planetary gearing, an auxiliary shaft, means drivingly connecting said auxiliary shaft with said input shaft, selectively engageable and disengageable means for drivingly connecting said auxiliary shaft to a third member of said output planetary gearing, fixed means, and selectively engageable and disengageable means for operatively connecting a fourth member of said planetary gearing with said fixed means for holding said fourth member against movement. 16. Apparatus as defined in claim 15 including a power take-off shaft disposed in substantial alignment with said auxiliary shaft and in spaced parallel relationship to said input shaft, and selectively engageable and disengageable means for drivingly connecting said power take-off shaft with said auxiliary shaft. 17. An extended range hydraulic transmission comprising an input shaft, an intermediate shaft substantially aligned with said input shaft an output shaft substantially aligned with said intermediate shaft, hydraulic transmission means including a pair of separate hydraulic elements, means providing hydraulic communication between said elements, one of said hydraulic elements being drivingly connected with said input shaft, another of said hydraulic elements being drivingly connected with said intermediate shaft, output planetary gearing comprising a plurality of members, one of said members of the output planetary gearing being drivingly connected with said intermediate shaft, said output shaft being drivingly connected with another of said members of said output planetary gearing, an auxiliary shaft disposed in spaced parallel relation to said input shaft, intermediate shaft and output shafts, means drivingly connecting said auxiliary shaft with said input shaft, selectively engageable and disengageable means for operatively connecting said auxiliary shaft to a third member of said output planetary gearing, fixed means, a selectively engageable and disengageable means for operatively connecting a fourth member of the output planetary gearing to said fixed means for holding said last-mentioned member of the output planetary gearing against movement. 18. Apparatus as defined in claim 17 including a power take-off shaft disposed in substantial alignment with said auxiliary shaft and in spaced parallel relationship to said input shaft, intermediate shaft and output shaft, and selectively engageable and disengageable means for drivingly connecting said power take-off shaft with said auxiliary shaft. 19. An extended range hydraulic transmission comprising an input shaft, an auxiliary shaft substantially in line with said input shaft, an intermediate shaft disposed in spaced parallel relation to said input shaft, an output shaft substantially aligned with said intermediate shaft, hydraulic transmission means including a pair of separate hydraulic elements, means providing hydraulic communication between said elements, one of said hydraulic elements being drivingly connected with said input shaft, another of said hydraulic elements being drivingly connected with said intermediate shaft, output planetary gearing comprising a plurality of members, one of said members of said output planetary gearing being drivingly connected with said intermediate shaft, said output shaft being drivingly connected with another of said members of the output planetary gearing, means drivingly connecting said auxiliary shaft with said input shaft, selectively engageable and disengageable means for operatively connecting said auxiliary shaft to a third member of said output planetary gearing, fixed means, a selectively engageable and disengageable means for operatively connecting an additional planetary gear element of the output planetary gearing to said fixed means for holding said last-mentioned element of the output planetary gearing against movement. 20. An extended range hydraulic transmission comprising an input shaft, an output shaft, hydraulic transmission means including a pair of separate hydraulic elements, means providing hydraulic communication between said elements, one of said hydraulic elements being drivingly connected with said input shaft, output planetary gearing comprising a plurality of members, said output planetary gearing including sun gear means drivingly connected with another of said hydraulic elements, said output planetary gearing including carrier means and planet gear means rotatably supported by said carrier means, said planet gear means being in meshing engagement with said sun gear means, said carrier means being drivingly connected with said output shaft, said output planetary gearing including first ring gear means, said first ring gear means being in meshing engagement with said planet gear means, fixed means, selectively engageable and disengageable means for operatively connecting said first ring gear means to said fixed means for holding said first gear means against rotation, an auxiliary shaft, means drivingly connecting said auxiliary shaft with said input shaft, said output planetary gearing including an additional planetary gear element, and selectively engageable and disengageable means for drivingly connecting said auxiliary shaft with said additional gear means. 21. Apparatus as defined in claim 20 wherein said additional gear means comprises second ring gear means and second planet gear means in meshing engagement with said second ring gear means. 22. Apparatus as defined in claim 21 wherein said second ring gear means is formed integral with said carrier means. 23. Apparatus as defined in claim 20 wherein said additional gearing includes second ring gear means, second planetary gear means carried by said carrier means, and said second ring gear means being in meshing engagement with said second carrier means. 24. An extended range hydraulic transmission comprising an input shaft, an intermediate shaft substantially aligned with said input shaft, an output shaft substantially aligned with said intermediate shaft, hydraulic transmission means including a pair of separate hydraulic elements, means providing hydraulic communication between said elements, one of said hydraulic elements being drivingly connected with said input shaft, output planetary gearing comprising a plurality of members, said output planetary gearing including a pair of sun gear means, each of said sun gear means being drivingly connected with said intermediate shaft which is in turn drivingly connected with another of said hydraulic elements, said output planetary gearing including first carrier means, said first carrier means being drivingly connected with said output shaft, planetary gear means rotatably supported by said first carrier means and being in meshing engagement with one of said sun gear means, first ring gear means in meshing engagement with said planetary gearing means, fixed means, selectively engageable and disengageable means for operatively connecting said first ring gear means with sadi fixed means for holding said first ring gear means against movement, second ring gear means formed integral with said first carrier means, second carrier means, second planet gear means in meshing engagement with said second ring gear means and also being in meshing engagement with another of said sun gear means, an auxiliary shaft disposed in spaced parallel relation to said input shaft, intermediate shaft and output shafts, means drivingly connecting said auxiliary shaft with said input shaft, and selectively engageable and disengageable means for operatively connecting said auxiliary shaft with said second carrier means. .Iadd. 25. In a power train, in combination an input shaft, an output shaft, .[..[..Iadd.speed differential.Iaddend..]..]. .Iadd.output .Iaddend..Badd.planetary .Baddend..Iadd.gear means connected to said output shaft .Iaddend..Badd.for selectively driving said output shaft in a continuously variable reverse and low forward speed range stage of operation and in a continuously variable extended high forward speed range stage of operation .Baddend..Iadd.and including two separate drive input members drivingly interconnected with one another, first drive transmitting means .Iaddend..Badd.connecting said input shaft to a first one of said drive input members for driving said output planetary gear means both during said reverse and low forward speed range stage of operation and during said extended high forward speed range stage of operation and .Baddend..Iadd.including .Iaddend..[..[..Iadd.hydrostatic.Iaddend..]..]. .Badd.hydraulic .Baddend..Iadd.transmission means drivingly connected to said input shaft and .[..[..Iadd.a.Iaddend..]..]. .Badd.to said .Baddend..Iadd.first one of said separate drive input members .Badd.for driving said first drive input member variably, relative to unidirectional rotational speed of said input shaft, between a first relative speed in one direction of rotation and a second relative speed in the opposite direction of rotation.Baddend..Iadd., second drive transmitting means .Iaddend..Badd.connected to said input shaft and to the other one of said drive input members for driving said output planetary gear means only during said extended high forward speed range stage of operation and .Baddend..Iadd.including a first engageable and disengageable means for drivingly connecting and disconnecting said input shaft to said .Iaddend..[..[..Iadd.second.Iaddend..]..]. .Badd.other .Baddend..Iadd.one of said separate drive input members, second engageable and disengageable means operatively connected with the output .Iaddend..Badd.planetary .Baddend..Iadd.gear means and cooperating with said first engageable and disengageable means for converting said output .Iaddend..Badd.planetary .Baddend..Iadd.gear means to drive said output shaft in either one of .Iaddend. .[..[..Iadd.two conditions.Iaddend..]..]. .Badd.said stages of operation .Baddend..Iadd., the .Iaddend..[..[..Iadd.first condition.Iaddend..]..]. .Badd.reverse and low forward speed range stage of operation .Baddend..Iadd.being a single input drive condition .Iaddend..Badd.allowing continuously variable reverse and low forward speed rotation of said output shaft as said first drive input member is varied in its relative speed of rotation from said first relative speed to said second relative speed .Baddend..Iadd.wherein said first drive input member drives both said output shaft and said .Iaddend..[..[..Iadd.second.Iaddend..]..]. .Badd.other .Baddend..Iadd.drive input member with said .Iaddend..[..[..Iadd.second.Iaddend..]..]. .Badd.other .Baddend..Iadd.second input drive member being driven by said first drive input member, the .Iaddend..[..[..Iadd.second condition.Iaddend..]..]. .Badd.extended high speed range stage of operation .Baddend..Iadd.being a dual input drive condition wherein said first and .[..[..Iadd.second.Iaddend..]..]. .Badd.other .Baddend..Iadd.drive input members differentially drive said output shaft .Iaddend..Badd.to effect continuously variable extended high forward speed range rotation of said output shaft as said first drive input member is varied in its relative speed of rotation from said second relative speed back toward said first relative speed.Baddend..Iadd., said first engageable and disengageable means being engaged under synchronous conditions when said output .Iaddend..Badd.planetary .Baddend..Iadd.gear means is converted to said .Iaddend..[..[..Iadd.second condition.Iaddend..]..]. .Badd.extended high forward speed range stage of operation .Baddend..Iadd.and said first engageable and disengageable means being disengaged under synchronous conditions when said output .Iaddend..Badd.planetary .Baddend..Iadd.gear means is converted to said .Iaddend..[..[..Iadd.first condition.Iaddend..]..]. .Badd.reverse and low forward speed range stage of operation..Baddend. .Iadd. 26. Apparatus as defined in claim 25 wherein said first engageable and disengageable means for drivingly connecting and disconnecting said .Iaddend..[..[..Iadd.second.Iaddend..]..]. .Badd.other .Baddend..Iadd.drive transmitting means under synchronous conditions comprises clutch means. .Iaddend..Iadd. 27. Apparatus as defined in claim 25 wherein said second engageable and disengageable means .Iaddend..Badd.operatively connected with said output planetary gear means and cooperating with said first engageable and disengageable means .Baddend..Iadd.for converting said output .Iaddend..Badd.planetary .Baddend..Iadd.gear means .Iaddend..[..[..Iadd.between said first and second drive conditions.Iaddend..]..]. .Badd.to drive said output shaft in either one of said stages of operation .Baddend..Iadd.comprises brake means. .Iaddend..Iadd. 28. Apparatus as defined in claim 25 wherein said .Iaddend..[..[..Iadd.hydrostatic.Iaddend..]..]. .Badd.hydraulic .Baddend..Iadd.transmission means drives said first one of said separate drive input members at a variable speed ratio with respect to the input shaft, said second drive transmitting means driving the other input member from said input shaft at a fixed speed ratio with respect thereto when said first engageable and disengageable means is engaged. .Iaddend. .Iadd. 29. Apparatus as defined in claim 25 wherein said first drive transmitting means includes a drive shaft which .Iaddend..[..[..Iadd.may be.Iaddend..]..]. .Badd.is .Baddend..Iadd.driven .Iaddend..[..[..Iadd.at different speed ratios.Iaddend..]..]. .Badd.between said first and second relative speeds .Baddend..Iadd.with respect to said input shaft, said second drive transmitting means including a drive member driven at fixed speed ratio with respect to said input shaft, so that in said .Iaddend..[..[..Iadd.first condition.Iaddend..]..]. .Badd.reverse and low forward speed range stage of operation .Baddend..Iadd.of said output .Iaddend..Badd.planetary .Baddend..Iadd.gear means both said output shaft and said .Iaddend..[..[..Iadd.second.Iaddend..]..]. .Badd.other drive .Baddend..Iadd.input member are driven at speeds which are proportional to the speed of said drive shaft but which may vary in speed ratio with respect to said input shaft, whereby at a predetermined speed ratio between said input shaft and said drive shaft the speeds of said .Iaddend..[..[..Iadd.second.Iaddend..]..]. .Badd.other drive .Baddend..Iadd.input member and said drive member of the second drive .Iaddend..Badd.transmitting .Baddend..Iadd.means are synchronized such that said first engageable and disengageable means can be engaged under synchronous conditions when said output gear means is converted to said .Iaddend..[..[..Iadd.second condition.Iaddend..]..]. .Badd.extended high forward speed range stage of operation .Baddend..Iadd.as said predetermined speed ratio .Iaddend..Badd.between said input shaft and said drive shaft .Baddend..Iadd.is achieved. .Iaddend.