In most forklifts, the sump (tank) is integrated into the frame. Since the fluid is heated by resistance from the system, this design enables the frame to act as a heat sink – a cooling system. The heat in the oil is drawn off by the entire truck.

The pump produces a constant, even flow of hydraulic fluid to supply the control valve. Most forklifts use a gear-type pump that consists of a pair of rotating meshed gears which push the fluid in a direction opposite their rotation.

The control valve is the brain of the system. It controls where the fluid is directed by using spools. It also controls the amount of fluid directed into a system line.

A relief valve protects the entire system in case of pressure overload or other trouble. For example, when a cylinder reaches the end of its travel, pressure in the system will raise. The spring-loaded relief valve senses excessive pressure build-up and opens, allowing oil to flow back into the sump.

Return lines return fluids to the sump. An electric truck has two hydraulic pumps, one for upright lift, tilt and auxiliary, plus a separate pump for the power steering cylinder.

Contact Hanjiu technology for answers on your forklift hydraulics!