Abstract: To increase the top speed of a multi-speed range hydromechanical steering transmission for tracklaying vehicles, the displacements of the hydraulic motors in the two hydrostatic drive units are abruptly destroked from 100% displacement to 80% displacement at the moment the infinitely variable displacements of their respective hydraulic pumps achieve zero displacement during acceleration through the highest forward speed range of the transmission.

Abstract: An infinitely variable speed hydromechanical steering transmission includes a range-changing mechanism flanked by a pair of hydrostatic units which are commonly driven by a mechanical input to produce respective mechanical and hydrostatic outputs. These outputs are combined in left and right output planetary gear sets which are interconnected by a cross-shaft extending centrally through the range-changing mechanism and hydrostatic units. The range-changing mechanism includes a plurality of clutches and brakes that are selectively engaged in pairs to incrementally change the mechanical output speed on the cross-shaft and thus to operate the transmission in a plurality of forward and reverse speed ranges. Each range change is accomplished by a step change in the hydrostatic outputs.

Abstract: An infinitely variable steering transmission is constructed to utilize the unidirection, continuous outputs of a pair of traction drive units for accelerating and decelerating a track-laying vehicle through a first forward and reverse propulsion range and a plurality of higher forward propulsion ranges and for developing steering power in all ranges. The transmission includes a pair of interconnected output planetary gears sets and a single input planetary gear set for combining the traction drive unit outputs and the constant speed input from a suitable prime mover for first and third range propulsion and steering power. Second range propulsion and steering power is obtained exclusively from the traction drive units in a manner to also provide steer cancellation, a continuous drive unit stroking pattern, and synchronous range shifting.

Abstract: A drive system for track-laying vehicles utilizes a pair of separate and independent motors to drive a multi-range, infinitely variable steering transmission pursuant to developing two track driving transmission outputs. The transmission includes a pair of interconnected output planetary gears sets which are separately driven by the two motors to develop first range forward and reverse propulsion and steering power at the transmission outputs as sun to carrier reductions. The transmission is shiftable into a second, higher speed range, wherein the two motor outputs are additional combined in one of the output planetary gear sets uniquely constructed to produce second range forward propulsion and steering power, as well as steer cancallation at the transmission outputs.

Abstract: A simplified range changing mechanism for an infinitely variable, split output, synchronously shifting hydromechanical steering transmission having integral steering and four forward ranges wherein the first, second and third forward ranges have progressively lower torque and higher speed propulsion ratios, while the fourth forward range is basically a repeat of the second range, by at a higher gear ratio. Positive steer with constant steering torque ratio is maintained in all four ranges.

Abstract: An additional range device for an infinitely variable split output synchronously shifting hydromechanical steering transmission having integral steering and multiple forward ranges wherein the additional range device provides an additional different input to an existing range mechanism to drive that range mechanism in a new speed range to constitute a new higher range for the transmission.

Abstract: A simplified range change mechanism for an infinitely variable, split output, synchronously shifting hydromechanical steering transmission having integral steering and at least three forward ranges having progressively lower torque and higher speed propulsion ratios in successively higher ranges while maintaining positive steer with a constant steering torque ratio in all ranges.

Abstract: An infinitely variable split output synchronously shifting hydromechanical steering transmisson having integral steering and at least three forward ranges having progressively lower torque and higher speed propulsion ratios in successively higher ranges while maintaining positive steer with a constant steering torque ratio in all ranges.

Abstract: An improved multirange synchronous shifting hydromechanical transmission wherein an overrunning clutch in parallel with the friction clutch of the lower gear range of two adjacent ranges is used to permit bridging the discontinuity in efficiency curves of the two ranges at the shift point to sustain operation under a load condition falling between the two efficiency curves and to prevent "hunting" during shifts between the two ranges.

Abstract: A multi-range synchronous shifting concentric gear train package having two inputs and a single output which when connected to a mechanical input and to the output of an infinitely variable drive device (shown as a hydrostatic component) powered by the same mechanical input with the input axes aligned with the center of rotation of the components of the gear package forms an all concentric multi-range synchronous shifting hydro-mechanical transmission. The combination of the same gear train package with mechanical and hydrostatic inputs in combination with right and left output planetary gear sets and a hydrostatic steer arrangement powered by the same mechanical input forms a hydromechanical steering transmission having a concentric gear train package. Gear train elements for exchanging the rotational movement of inner and outer shafts of a set of concentric shafts to permit implementation of the concentric gear train package are also disclosed in detail.

Abstract: A multi-range synchronous shifting concentric gear train package having two inputs and a single output which when connected to a mechanical input and to the output of an infinitely variable drive device (shown as a hydrostatic component) powered by the same mechanical input with the input axes aligned with the center of rotation of the components of the gear package forms an all concentric multi-range synchronous shifting hydromechanical transmission. The combination of the same gear train package with mechanical and hydrostatic inputs in combination with right and left output planetary gear sets and a hydrostatic steer arrangement powered by the same mechanical input forms a hydromechanical steering transmission having a concentric gear train package. Gear train elements for exchanging the rotational movement of inner and outer shafts of a set of concentric shafts to permit implementation of the concentric gear train package are also disclosed in detail.