How Does a Spool Valve Work?

The spool valve is integrated with the backhoe loader and acts as a switching mechanism to direct oil to either side of a ram in a hydraulic mechanism. The spool valve system allows the backhoe to shift the piston in two directions.

The oil from the tank is pumped to the spool valve through a hose. When the engineer shifts the controls to switch the direction of the backhoe, the spool valve alters its configuration so the high-pressure oil is directed to the other side of the ram. When the high-pressure oil gets directed to one side, the low-pressure oil is pushed back into the oil tank through a different hose.

The spool valve block is controlled by the joysticks in the backhoe cab. The joystick operates the hydraulic piston that controls the motion of the spool valves. When the joystick is pushed in a certain direction, it pushes down a specific piston, and the piston pushes oil through a hose to move the spool valve controlling a specific hydraulic ram. Different spools shift, extend or retract the various hydraulic pistons. In some hydraulic systems, control sticks act as levers and are directly attached to the spool valve to move the spool.