Patent ID: 9574329
Date: 2017-02-21
CPC Classifications: E02F,F15B

Claim:
1. A shovel, comprising: a plurality of hydraulic actuators driven by using hydraulic oil and including a first hydraulic actuator and a second hydraulic actuator, the first hydraulic actuator and the second hydraulic actuator being driven by causing the hydraulic oil to flow thereinto and therefrom; a first pressure detector configured to detect a first pressure of the hydraulic oil flowing out of the first hydraulic actuator; a second pressure detector configured to detect a second pressure of the hydraulic oil in the second hydraulic actuator; a main pump; a hydraulic pump-motor configured to function as a hydraulic motor by using the hydraulic oil flowing out of the first hydraulic actuator upon detecting that the first pressure detected by the first pressure detector is higher than or equal to a predetermined threshold pressure that is higher than the second pressure detected by the second pressure detector, and configured to function as a hydraulic pump upon detecting that the first pressure is lower than the predetermined threshold pressure; a control valve configured to control a flow of the hydraulic oil in the plurality of hydraulic actuators; a first oil passage to connect the main pump with the second hydraulic actuator through the control valve; and a second oil passage to connect the hydraulic pump-motor with the second hydraulic actuator, the second oil passage meeting the first oil passage between the control valve and the second actuator, wherein the hydraulic pump-motor suctions the hydraulic oil flowing out of the first hydraulic actuator and discharges the hydraulic oil to the second hydraulic actuator.