APPARATUS FOR CONTROLLING A HYDRAULIC PUMP FOR OPTION ATTACHMENT IN AN EXCAVATOR

摘要

Pressured oil passes thru an option valve(2) but not thru a by-pass line(5), pressure is not applied to a control valve(6). However the pressured oil delivered from an auxiliary pump(8) flows in a pressure reduction valve(13) wherein it is adjusted to agree with the option operator and sent to the shuttle valve(14). The shuttle valve chooses the larger pressure and delivers it to the pump regulator, of the two pressures: one supplied from the negative control valve(6) thru a pilot line(15) and the one supplied from a ratio pressure reduction valve(13).