Patent ID: 6018895
Filing Date: 2000-02-01
Classification: E02F

Abstract:
A power machine, comprisinga base;a boom coupled to the base;a hydraulic boom actuator coupled to the boom to move the boom relative to the base;an arm coupled to the boom;a hydraulic arm actuator coupled to the boom and the arm to move the arm relative to the boom;a tool coupled to the arm;a tool actuator coupled to the tool to move the tool relative to the arm;a traction actuator coupled to the base to drive the power machine;a hydraulic power circuit including a first pump providing hydraulic fluid under pressure and a second pump providing hydraulic fluid under pressure;a traction valve mechanism coupled to the traction actuator to receive hydraulic fluid under pressure from one of the first and second pumps and selectively provide the hydraulic fluid to the traction actuator;a boom valve coupled to the first pump and to the boom actuator to receive hydraulic fluid under pressure from the first pump and selectively provide the hydraulic fluid to the boom actuator;an arm valve coupled to the second pump and the arm actuator to receive hydraulic fluid under pressure from the second pump and selectively provide the hydraulic fluid to the arm actuator; anda tool valve coupled in parallel with the arm valve and to the tool actuator to receive hydraulic fluid under pressure from the second pump and selectively provide the hydraulic fluid to the tool actuator;wherein at least one of the boom valve and the parallel connected arm valve and tool valve are coupled down stream of, and in series with, the traction valve mechanism.