Travel control valve

摘要

A travel control valve includes a valve body and a spool. The valve body includes a first pump port connected on an upstream side from a drive control valve, a first connection port connected on a downstream side from the drive control valve, a second pump port connected to a second pump, and a second connection port connected to a second circuit system. The travel control valve can switch a communication opening between the first pump port and the first connection port to a large opening throttle position in which the communication opening remains smaller than that between the second pump port and the second connection port, and a small opening throttle position in which the communication opening remains smaller than that in the large opening throttle position.

主权项

1. A travel control valve used in a power shovel comprising:
a first circuit system that is connected to at least one control valve for operating an actuator and connected to a drive control valve for controlling a fluid pressure motor for driving a wheel type travelling body on an uppermost stream; a first pump that is connected to the first circuit system and adapted to supply a working fluid; a second circuit system that is connected to at least one control valve for operating an actuator; a second pump that is connected to the second circuit system and adapted to supply a working fluid; a valve body; and a spool that is slidably arranged inside the valve body, wherein the valve body includes: a first pump port that is connected to the first pump on an upstream side from the drive control valve; a first connection port that communicates with the first pump port and is connected on a downstream side from the drive control valve of the first circuit system; a second pump port that is connected to the second pump; and a second connection port that communicates with the second pump port and is connected to the second circuit system, wherein a communication opening between the first pump port and the first connection port is switchable to a large opening throttle position in which the communication opening remains smaller than that between the second pump port and the second connection port and a small opening throttle position in which the communication opening remains even smaller than that in the large opening throttle position according to a slide position of the spool.