Drive device

A drive device for a vehicle, the drive device comprising:

• a center section disposed in a housing;
• a hydraulic pump comprising a first cylinder block having a plurality of axial pistons disposed therein, the first cylinder block being disposed on a first portion of the center section and hydraulically connected to a hydraulic motor comprising a second cylinder block disposed on a second portion of the center section, wherein the hydraulic pump is powered by a pump input shaft extending into the housing;
• a motor shaft engaged to and driven by the hydraulic motor, and at least one output axle driven by the motor shaft and extending out of the housing to power the vehicle;
• and
• a trunnion arm extending into the housing and having an interface portion engaged to a swash plate to rotate the swash plate between a neutral position and a plurality of actuated positions, wherein the swash plate is engaged to the plurality of axial pistons of the hydraulic pump and comprises a pocket on one side thereof to receive the interface portion of the trunnion arm, the pocket having a first internal pocket side and a second internal pocket side, and the interface portion comprises:
• a first interface side and a second interface side opposite the first interface side;
• a third interface side extending between the first interface side and the second interface side;
• and
• a fourth interface side, opposite the third interface side, and extending between the first interface side and the second interface side;
• wherein (i) the first interface side and the second interface side are both arcuate in shape, through their entire lengths between the third interface side and the fourth interface side, (ii) the first interface side slidingly engages the first internal pocket side and the fourth interface side slidingly engages the second internal pocket side during rotation of the swash plate;
• and (iii) one of the first interface side or the second interface side directly contacts its respective first internal pocket side or second internal pocket side when the swash plate is in the neutral position.

A drive device for a vehicle, the drive device comprising:

• a variable displacement hydraulic pump;
• a swash plate engaged to the hydraulic pump and comprising a pocket with a first side and a second side generally opposite thereto, the swash plate being rotatable about a first axis of rotation between a neutral position and a plurality of actuated positions;
• a trunnion arm engaged to the swash plate and rotatable about a second axis of rotation, wherein the second axis of rotation is offset from the first axis of rotation;
• an interface portion formed on a first end of the trunnion arm and engaged to the pocket, the interface portion comprising a first interface arcuate side and a second interface arcuate side generally opposite thereto, wherein the first interface arcuate side slidingly engages the first side of the pocket as the trunnion arm is rotated in a first direction, and the second interface arcuate side slidingly engages the second side of the pocket as the trunnion arm is rotated in a second direction opposite the first direction, and one of the first interface arcuate side or the second interface arcuate side is directly engaged to the respective first side or second side of the pocket when the swash plate is in the neutral position;
• and
• a control arm attached to a second end of the trunnion arm, wherein rotation of the control arm results in an equivalent rotation of the trunnion arm and a lesser rotation of the swash plate.