| 摘要 |
PROBLEM TO BE SOLVED: To extend a jack cylinder at high speed until grounding of a jack grounding plate and extend the jack cylinder at normal speed after grounding of the jack grounding plate in jack extension operation.SOLUTION: An outrigger jack speed control device of a work vehicle includes: a differential circuit 4 provided in a hydraulic circuit of an outrigger jack and capable of extending a jack cylinder 17 at high speed and extending it at normal speed depending on an amount of discharge oil from a jack cylinder contraction side oil chamber 17b when extending the jack cylinder 17; jack reaction force detection means 5 for detecting reaction force of the outrigger jack; and control means 3 that maintains the differential circuit in a state that the jack cylinder extends at high speed when the jack reaction force detection means detects low jack reaction force and maintains the differential circuit in a state that the jack cylinder extends at normal speed when the jack reaction force detection means detects high jack reaction force. |
