Abstract: A position indication derived from the output signal of an engine demand device sensor is compensated for errors which tend to expand or contract the range of such output signal. The signal is compared to previously stored upper and lower reference values nominally corresponding to the limit positions of the demand device, and the position indication is derived in accordance with such comparison. The compensation is achieved by altering the previously stored upper and lower reference values at the initiation of each period of vehicle operation, in a sense to contract the range of output signals defined thereby, and by replacing the upper or lower reference values with the sensor output signal value during the ensuing period of vehicle operation if the sensor output signal value is greater or less than the upper or lower reference values, respectively.

Abstract: A transmission having a plurality of gear ratios which are selectively engaged on the supply of fluid to a servo motor fluid chamber and controls. The controls have a source of fluid under regulated pressure selectively connected by a relay valve respectively in a first and a second position to a first and a second servo motor to provide a first and a second ratio drive, an automatic shift valve controlled by speed and torque demand for shift movement between a first and a second position having spaced lands slidably sealed in a bore and a smaller intermediate restricting portion providing a restricted passage between the bore and restricting portion operative in the first position to restrictively connect the actuator chamber of the relay valve so the relay valve is in first position and in the second position to restrictively connect said source to the actuator chamber of the relay valve to shift the relay valve to second position.

Abstract: A multiratio powershift transmission having fluid operated drive devices including a forward clutch with an apply chamber supplied with fluid apply pressure to engage the clutch for forward drives and exhausted to disengage the clutch for reverse drive. The apply chamber is in a housing rotating at input speed during forward and reverse drive. In forward drive, a dump valve mounted on the rotating housing is biased closed by a spring, static fluid apply pressure, and centrifugal pressure head, in the rated input speed range. At a higher speed, centrifugal force on the dump valve element opens the dump valve to exhaust the apply chamber and disengage forward drive. In reverse drive, the dump valve is biased closed only by the spring which at idle speed closes the dump valve, and at a low speed used in reverse drive, centrifugal force opens the dump valve to flush the dump valve during reverse drive.

Abstract: The power train has a manual throttle controlled gas turbine engine having a high no load idle speed and a transmission having a low capacity fluid coupling and a variable capacity slipping friction clutch connected in parallel to the input of a multiratio gear unit for driving a vehicle. During engine idle with the vehicle stationary, when the gear unit is in neutral, the fluid coupling is unloaded to permit the engine to operate and drive the accessories at a high no load idle speed. When the gear unit is placed in a drive ratio, the fluid coupling is stalled loading the engine and reducing the no load idle speed to a regulated lower drive starting idle speed range, to reduce the inertia energy level for smooth drive starting clutch engagement and to maintain the engine output speed in a proper vehicle accessory operating idle speed range.

Abstract: A transmission having a plurality of gear ratios which are selectively engaged on the supply of fluid to a servo motor fluid chamber and controls. The controls have a source of fluid under regulated pressure selectively connected by a relay valve respectively in a first and a second position to a first and a second servo motor to provide a first and a second ratio drive, an automatic shift valve controlled by speed and torque demand for shift movement between a first and a second position having spaced lands slidably sealed in a bore and a smaller intermediate restricting portion providing a restricted passage between the bore and restriction portion operative in the first position to restrictively connect the actuator chamber of the relay valve so the relay valve is in first position and in the second position to restrictively connect said source to the actuator chamber of the relay valve to shift the relay valve to second position.

Abstract: An automatic multiratio drive transmission having an automatic shift control system with a speed and throttle position pressure controlled shift valve controlling shifts between the highest drive ratio and the next lower drive ratio. When the shift valve is in the lower drive ratio position, a normal speed pressure signal increasing with increasing speed acting on the shift valve overcomes an opposing bias force controlled by throttle pressure to upshift the shift valve to the higher drive ratio position at increasing upshift speeds for increased throttle positions and provides an upshift hysteresis force decreasing with increasing throttle positions to prevent shift cycling as the highest ratio is established in a short time period and after a longer time delay period reduces the normal speed related governor pressure in an amount equal to the upshift hysteresis force at full throttle so that the downshift speed is the same as the upshift speed at the full throttle position.

Abstract: A transmission having selectively engaged fluid actuated friction drive establishing devices and an engagement timing control system having a trimmer regulator valve for each drive establishing device, a trimmer bias regulator valve and accumulator. The oncoming trimmer valve has a spring biasing device responsive to engagement pressure to increase oncoming ratio drive engagement pressure at a controlled rate, initially at a high rate up to a minimum slack take up pressure, then to gradually increase the drive pressure from the minimum pressure at a low rate in a predetermined trimming time period for establishing the drive and then to increase the pressure at a very high rate to high line pressure. A trimmer bias system pressure is supplied to a bias chamber of the trimmer valves and acts in the oncoming trimmer valve bias chamber to increase the pressure level of the gradually increasing drive engagement pressure proportional to torque demand.

Abstract: The power train has a manual throttle controlled gas turbine engine having a high no load idle speed and a transmission having a low capacity fluid coupling and a variable capacity slipping friction clutch connected in parallel to the input of a multiratio gear unit for driving a vehicle. During engine idle with the vehicle stationary, when the gear unit is in neutral, the fluid coupling is unloaded to permit the engine to operate and drive the accessories at a high no load idle speed. When the gear unit is placed in a drive ratio, the fluid coupling is stalled loading the engine and reducing the no load idle speed to a regulated lower drive starting idle speed range, to reduce the inertia energy level for smooth drive starting clutch engagement and to maintain the engine output speed in a proper vehicle accessory operating idle speed range.