SYSTEM / Hydraulic System Operation Control Circuit The pilot valves control pressure oil from the pilot pump and operates the control valve spools. The signal control valve is provided between the pilot valves and the control valve. The shockless valve (in boom raise circuit) built in the signal control valve dampens quick spool movement in the control valve. (Refer to the COMPONENT OPERATION / Signal Control Valve group.) The shockless valve (in boom lower circuit) pro- vided between the right pilot valve and the signal control valve dampens quick spool movement in the control valve. T2-4-4