公开(公告)号：US11313103B2

公开(公告)日：2022-04-26

申请号：US16641484

申请日：2019-03-22

Applicant: Hitachi Construction Machinery Co., Ltd.

Inventor： Keishi Mizutani ,  Ryousuke Matsutani ,  Shinichiro Tanaka

IPC: B60T17/22 ,  E02F9/20 ,  E02F9/22 ,  B60T13/68

Abstract: A work vehicle provided with a loading hydraulic circuit (A), including at least a main hydraulic pump (31), a lift arm cylinder (8) and a control valve (32), an auxiliary hydraulic pump (31), a negative parking brake device (PB), and a parking brake releasing hydraulic circuit (B2), in which the vehicle includes: a loading operation hydraulic circuit (B1) located upstream of the parking brake releasing hydraulic circuit; an emergency flow path (80) for supplying the pressure oil discharged from the auxiliary hydraulic pump to the parking brake device through the loading operation hydraulic circuit in an emergency; and a valve unit (81) located in the emergency flow path. If the pressure of the parking brake releasing hydraulic circuit is lower than the brake release pressure to release the braking state of the parking brake device, the valve unit is switched to the communicating position.