Abstract: A method is provided for controlling a torque output of an hydrostatic motor in fluid communication with a variable displacement pump. At least one of the motor and pump has variable displacement capabilities. The method includes monitoring at least one motor condition of the hydrostatic motor and determining a displacement signal corresponding to the monitored motor condition. The variable displacement capabilities are controlled based on the displacement signal to reduce a torque ripple in the torque output of the hydrostatic motor.

Abstract: A method is provided for controlling a torque output of an hydrostatic motor in fluid communication with a variable displacement pump. At least one of the motor and pump has variable displacement capabilities. The method includes monitoring at least one motor condition of the hydrostatic motor and determining a displacement signal corresponding to the monitored motor condition. The variable displacement capabilities are controlled based on the displacement signal to reduce a torque ripple in the torque output of the hydrostatic motor.

Abstract: In many hydraulic systems, fluid-borne noise is generated during operation due to the effects of the hydraulic pump. This fluid-borne noise is then transmitted to the hydraulic valves, hydraulic lines, and other structure that valves and lines are mounted on. These structures then emit vibrations that create the largest portion of the system air-borne noise. In the subject invention, an apparatus is provided for the attenuation of fluid-borne noise in a hydraulic system. The apparatus includes a mechanism for effectively sensing the flow ripple produced by the pump and a mechanism for transmitting a signal (C) representative of the flow ripple to a negative ripple generator which provides a corrective flow to the hydraulic system to cancel the flow ripple. By eliminating the flow ripple in the hydraulic system, the associated air-borne noise that is created by various components that are associated with the hydraulic system is attenuated.

Abstract: A drive train includes a hydrostatic transmission unit and a multiple speed range transmission unit arranged in series between a prime mover and a primary output shaft, variable displacement and torque transmitting capacity of the hydrostatic transmission unit being adjusted by hydraulic controls including a speed control valve for developing a differential pressure signal proportional to a desired rate of operation, a modulating valve for regulating the differential pressure signal corresponding to accelerating and decelerating operation of the transmission, a directional control valve for determining the direction of operation of the hydrostatic transmission unit, and a range selector valve for shifting the operating speed range of the multiple speed range transmission as the hydrostatic transmission approaches a limit of displacement, the displacement of the hydrostatic transmission being automatically reset in response to shifting of the multiple speed range transmission.

Abstract: A drive train includes a hydrostatic transmission unit and a multiple speed range transmission unit arranged in series between a prime mover and a primary output shaft, variable displacement and torque transmitting capacity of the hydrostatic transmission unit being adjusted by hydraulic controls including a speed control valve for developing a differential pressure signal proportional to a desired rate of operation, a modulating valve for regulating the differential pressure signal corresponding to accelerating and decelerating operation of the transmission, a directional control valve for determining the direction of operation of the hydrostatic transmission unit, and a range selector valve for shifting the operating speed range of the multiple speed range transmission as the hydrostatic transmission approaches a limit of displacement, the displacement of the hydrostatic transmission being automatically reset in response to shifting of the multiple speed range transmission.

Abstract: A drive train includes a hydrostatic transmission unit and a multiple speed range transmission unit arranged in series between a prime mover and a primary output shaft, variable displacement and torque transmitting capacity of the hydrostatic transmission unit being adjusted by hydraulic controls including a speed control valve for developing a differential pressure signal proportional to a desired rate of operation, a modulating valve for regulating the differential pressure signal corresponding to accelerating and decelerating operation of the transmission, a directional control valve for determining the direction of operation of the hydrostatic transmission unit, and a range selector valve for shifting the operating speed range of the multiple speed range transmission as the hydrostatic transmission approaches a limit of displacement, the displacement of the hydrostatic transmission being automatically reset in response to shifting of the multiple speed range transmission.

Abstract: Pneumatically operated devices respond to movement of a shift lever by decoupling change speed gears from both the input and output of a transmission and then brake the gears to a stop, shift gear engagements as necessary, release the brakes and re-engage the input and output clutches to re-establish drive at a newly selected drive ratio. A self-cycling control circuit is connected between the shift lever and pneumatic devices to actuate and deactuate such devices as necessary to accomplish a selected shift. The circuit includes means which enables re-engagement of the input and output clutches only after critical gear couplings and decouplings are established together with means which cycles the gears to facilitate engagements and disengagements if these have not occurred in a predetermined time. Means are also provided for preconditioning the system to respond quickly to a subsequent shift lever movement.