Control system for powershift transmission clutches
This patent describes a control system for selectively controlling the hydraulic fluid pressure supplied by a pump to the directional clutch valves in a powershift-type transmission. The system comprises: a first valve having a piston reciprocably disposed between first and second ends of a cylinder and biasing means disposed between the piston and the second cylinder end for biasing the piston toward the first cylinder end; the first cylinder end being in fluid communication with the pump and at least one of the directional clutch valves; the piston having an open position when biased toward the first cylinder end allowing fluid passage between the pump and the one of the direction clutch valves and a closed position when biased toward the second cylinder end preventing fluid passage between the pump and the one of the direction clutch valves; the first valve further including a feed back port extending between the pump and the second cylinder end allowing fluid flow therebetween in both the open and closed positions of the piston, the feedback port having a restriction to fluid flow therethrough; a second valve providing a fluid passage to vent the second cylinder end; actuator means for opening and closing the second valve whereby upon opening the fluid passage, the hydraulic fluid in the second cylinder end is displaced through the fluid passage reducing the hydraulic fluid pressure in the second cylinder end and causing a pressure differential across the piston due to the retarded flow through the feedback port such that the piston moves to the closed position.
- Assignee:
- Cooper Industries, Inc., Houston, TX
- Patent Number(s):
- US 4843902
- Application Number:
- PPN: US 7-208798A
- OSTI ID:
- 5493081
- Country of Publication:
- United States
- Language:
- English
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