HYDRAULIC CIRCUIT FOR CONSTRUCTION MACHINE

摘要

PROBLEM TO BE SOLVED: To solve the problem that traveling speed suddenly drops in the case of the work of fine operation which requires high load pressure when a travel straight valve is switched and to provide an hydraulic circuit for a construction machine superior in traveling performance and fuel consumption. SOLUTION: In the hydraulic circuit for construction machine provided with the travel straight valve at the upstream of the center oil path of one hydraulic pump and the upstream of the parallel path of the other oil hydraulic pump, a bypass oil path is provided from the upstream of one parallel oil path to the upstream of the travel control valve of the center oil path on the same side, and the bypass oil path is provided with a variable throttle valve and check valve to make the quantity of flow from the parallel oil path to the center oil path variable.