CONTROL VALVE FOR HYDRAULIC SYSTEM IN FORKLIFT TRUCK

摘要

A control valve for a hydraulic system in a forklift truck is provided to prevent lowering of initial driving power of a lift cylinder by preventing a shortage of hydraulic fluid introduced into the lift cylinder. A control valve for a hydraulic system in a forklift truck includes a first auxiliary notch unit(52), a second auxiliary notch unit(56), and a third auxiliary notch unit(58). The first auxiliary notch unit is formed at a first land unit(50) of a lift spool(40) to connect an introduction passage(34) with an entrance port(36) before a second notch unit(42) when the lift spool is moved to a first position(A) from a neutral position(N). The second auxiliary notch unit is formed at a second land unit(54) of the lift spool to connect a drain passage(38) with the in and out passage before the second notch unit when the lift spool is moved to a second position(B) from the neutral position. The third auxiliary notch unit is formed at a third land unit(57) of the lift spool to gradually increase and decrease an opening angle of the entrance port and a bypass passage(39) when the lift spool is moved between the neutral and first positions. The first and second auxiliary notch units have sections getting wider toward the second notch unit.