A steering system for a skid steered vehicle has a variable-speed steering motor, and an asymmetrical steering differential operatively connected to the steering motor and rotatably mounted on a first side of the chassis separately from the propulsion system. The steering differential has a first differential shaft and a second differential shaft, where the asymmetrical differential imparts a greater speed change on the second differential shaft than the first differential shaft. The first differential shaft is connected to a first steering output shaft operatively connected to at least one ground-engaging element on the first side of the vehicle. A speed reducer mounted fixedly on the chassis connects the second differential shaft to a second steering output shaft operatively connected to at least one ground-engaging element on the second side of the vehicle so that the second steering output shaft experiences the same speed change but in an opposite rotational direction as the first steering output shaft.

A bulldozer has a left planetary gear mechanism, a left steering clutch, and a first clutch gear. The left planetary gear mechanism is disposed between an input shaft and a left output shaft. The left steering clutch switches between transmitting and blocking a rotational force from the input shaft to the left output shaft by the left planetary gear mechanism. The first clutch gear is attached to the left steering clutch. The left steering clutch can is configured to be engaged or disengaged with a left sun gear. The first clutch gear is fixed in an unrotatable manner.

A bulldozer has a left planetary gear mechanism, a left steering clutch, and a first clutch gear. The left planetary gear mechanism is disposed between an input shaft and a left output shaft. The left steering clutch switches between transmitting and blocking a rotational force from the input shaft to the left output shaft by the left planetary gear mechanism. The first clutch gear is attached to the left steering clutch. The left steering clutch can is configured to be engaged or disengaged with a left sun gear. The first clutch gear is fixed in an unrotatable manner.

A system and method for differential traction drive and steering axis coordination for an autonomous mower or other turf device includes initiating a steering motion based on determining a target forward speed and a steering rotational speed, calculating a left wheel speed and a right wheel speed, and applying the left and right wheel speeds, wherein the steering rotational speed is driven by a steering motor and the traction wheels associated with the autonomous mower, and the left and right wheel speeds are based on the target forward speed, a distance from a steering axle to the center of the respective wheel, and the steering rotational speed.

A system and method for differential traction drive and steering axis coordination for an autonomous mower or other turf device includes initiating a steering motion based on determining a target forward speed and a steering rotational speed, calculating a left wheel speed and a right wheel speed, and applying the left and right wheel speeds, wherein the steering rotational speed is driven by a steering motor and the traction wheels associated with the autonomous mower, and the left and right wheel speeds are based on the target forward speed, a distance from a steering axle to the center of the respective wheel, and the steering rotational speed.

The invention comprises a transaxle having an electric motor that is controlled by a vehicle user and that drives at least one output axle. The transaxle includes a power generating device that powers the electric motor and a reduction gear train engaged to and driven by the electric motor. The transaxle includes a common housing in which the power generator, the electric motor, and the reduction gear system are each disposed. In dual-axle systems, the transaxle also includes a differential engaged to and driven by the reduction gear system to power a pair of oppositely extending output axles. The differential is also disposed within the common housing.

A continuously variable speed transmission and steering differential having a central drive axle, two pairs of sheaves and two shift arms. The drive axel is driven by an external power source. The two pairs of sheaves, left and right, are mounted to the drive axel. Each pair of sheaves includes a fixed drive sheave and a movable drive sheave. Each movable drive sheave is positioned by a shift arm. Shifting the shift arms left or right varies the gear ratio between the left and right pair of sheaves thereby providing steering control. Narrowing the distance between the shaft arms increases the gear ratio and consequently puts the transmission into a higher gear, thereby providing speed control.

A drive assembly (140) for a walk-behind, powered device operably couples an engine (110) of the powered device to a mobility assembly (120) to provide mobility of the powered device responsive at least in part to operation of the engine (110). The drive assembly (140) includes a transmission shaft and a mechanical power reversing assembly (150). The transmission shaft selectively receives first drive power or second drive power coupled from the engine (110) to drive a first drivable component (122) and a second drivable component (124) of the mobility assembly (120). The first and second drivable components (122, 124) are disposed substantially at opposing sides of the powered device. The mechanical power reversing assembly (150) is selectively engagable to convert the first drive power generated for the first drivable component (122) into the second drive power provided to the second drivable component (124) and vice versa.

A drive assembly (140) for a walk-behind, powered device operably couples an engine (110) of the powered device to a mobility assembly (120) to provide mobility of the powered device responsive at least in part to operation of the engine (110). The drive assembly (140) includes a transmission shaft and a mechanical power reversing assembly (150). The transmission shaft selectively receives first drive power or second drive power coupled from the engine (110) to drive a first drivable component (122) and a second drivable component (124) of the mobility assembly (120). The first and second drivable components (122, 124) are disposed substantially at opposing sides of the powered device. The mechanical power reversing assembly (150) is selectively engagable to convert the first drive power generated for the first drivable component (122) into the second drive power provided to the second drivable component (124) and vice versa.

A transmission for a vehicle, particularly a skid-steered vehicle, that employs motive power from a prime mover delivered through an input shaft to drive left and right drive shafts at a nominal speed and input power from an electric motor to vary the speed of the left and right drive shafts according to steering commands from a steering control structure. The speed of the left and right drive shafts is directly related to a speed of the input shaft and the nominal speed of the left or right drive shaft is varied upwardly or downwardly by a ratio of the speed of the steering shaft via a speed varying structure. The speed of the left and right drive shafts is simultaneously varied in opposite directions (i.e. upwardly and downwardly) relative to the nominal speed by an equal number of rotations.