PURPOSE: To stop the power assist to the handle operation at a high speed travel and improve high speed stability by setting a spool type control valve to the neutral position at a high speed travel and cutting off the supply of pressure oil to an output drive section.
CONSTITUTION: A lock cylinder unit 40 is provided at the housing 18 of a control valve 3. The lock cylinder unit 40 consists of a piston 42 that is deflected axially along with the valve spool 15 of the control valve 3, a lock cylinder 43 that houses the piston 42 slidably, a lock valve 45 that connects or disconnects the oil chambers 44a and 44b on both sides of the piston of the cylinder 43 mutually, an actuator 46 that drives the valve 45, and a control unit that drives the lock valve 45 in the close direction. Besides, at a high speed travel, the control unit drives the actuator 46, closes the lock valve 45, and locks the piston 42 and the valve spool 15 at the neutral position. As a result, the power assist is stopped and control of direction is performed only by the manual operation force.
| JPH10226345 | SOLENOID DRIVING GEAR |
| JP2003154961 | VEHICLE WHEEL POSITIONING DEVICE |
YAMAGISHI HIROHIKO
UJIHARA KEN
ARITA TSUNEFUMI
| JPS49120330A | 1974-11-18 |