US Patent 7621124 Travel vibration suppressing device for working vehicle

A travel vibration suppressing device 20 is structured such that a directional control valve 30 for a bucket, a directional control valve 29 for a boom, a ride control valve 31 and a boom speed increasing valve 33 are integrally arranged in a laminated manner by an internal piping. The ride control valve 31 communicates or cuts off a bottom chamber 11a of a boom cylinder 11 and an accumulator 27. The boom speed increasing valve 33 supplies a discharge pressure of a hydraulic pump 21 to the bottom chamber 11a or a head chamber 11b or connects the to the bottom chamber 11a or the head chamber 11b to a tank 23.