TRAVELING DEVICE FOR CRAWLER TYPE CONSTRUCTION MACHINE

摘要

PROBLEM TO BE SOLVED: To prevent abrupt decrease/increase of a traveling speed at a level sensed by a driver when composite work is carried out by simultaneously driving a right/left traveling device of a crawler type excavator and working devices.

SOLUTION: This traveling device for a crawler type construction machine includes: a straight traveling valve 13 respectively supplying hydraulic fluid from a first hydraulic pump 1 to switching valves 5 for the left and right traveling motors and respectively supplying hydraulic oil from a second hydraulic pump to switching valves 7 and 11 for the working devices in a working mode in which the traveling device and the working devices are simultaneously driven; a variable orifice arranged in a confluent passage connecting a second center bypass passage 9 in parallel with a passage branched from the upstream side, and intercepting the supply of the hydraulic fluid supplied to the working devices toward the traveling device through the confluent passage; a mode selection device 31 for selecting a working mode; an electromagnetic proportional valve 19 variably controlling oblique plate tilt angles of the first and second hydraulic pumps; and a controller for outputting control signals to electric control valves 21 and 25 respectively controlling signal pressure supplied to the straight traveling valve and the variable orifice.

COPYRIGHT: (C)2009,JPO&INPIT