Hydraulic Pumps are highly utilized parts in a forklift. For example, hydraulic pumps can be found in the power steering system, braking system, suspension system, and gear and motor system. The focus of the following article refers to the hydraulic pumps in gear and motor systems. Forklift lift truck Forklift Hydraulic Pumps found in the gear and motor systems provide the flow required to transmit power to a hydraulic actuator from a prime mover. There are two types of hydraulic pumps: centrifugal and positive displacement. Centrifugal involves the flow of the fluid transfer, which depends on the outlet pressure. Whereas the positive displacement depends independently on pressure. The hydraulic flow is created when the prime mover drives the pump rotating group, which forces fluids out of the pump outlet. When the fluid is forced out, a vacuum force is made at the pump inlet and its natural pressure pushes the fluids from the reservoir into the pump. Positive displacement pumps come in two forms: fixed displacement and variable displacement. Fixed displacement (hydrostatic) pumps have the flow varying only on the shaft speed. Its benefit is that it performs well, creating a constant flow and pressure. Variable displacement (hydrodynamic) pumps can have flow varying on any shaft speeds provided. Though variable displacement is the more expensive alternative of the two, it is more energy efficient. Also, it performs well for variable flow or pressure applications. Bad Gear Problem on a Hydraulic Pump A common hydraulic pump problem is one with bad gears. The bad gear problem may occur for various reasons such as wear, high temperature of the hydraulic fluid, fluid leaks and contamination, and aeration which occurs due to air pockets. Checking the hydraulic pump gears is as follows: Hydraulic pumps can be found inside or outside of the engine. To dissemble the pump, the bolts has to be unscrewed. They are found on the side for the outside pumps or the bottom for the inside pumps. Gasket should be removed with a sharp object. Once removed, the excess fluids has to be wiped off for clear visibility for measurements. The clearance should be measured between the gears and the pump’s housing cover with a straightedge. Generally the clearance is between .001 to .004 inches. When the measurement exceeds .005 inches, the gears should be replaced immediately. Also, ensure that the gears are absolutely installed into the pump and that their measurements are consistent. The gear teeth clearance to the pump body should be checked and ensured that the teeth length is consistent. Generally the clearance is between .001 to .005 inches. Check the specifications. All components should be cleaned prior to reassembling the pump. The gears and the pump housing should be cleaned and blow dried. Petroleum jelly can be applied to all inner components. The hydraulic pump is then reinstalled and primed as per the manufacturer’s instructions. If the findings from the above steps concludes that the components are damaged are worn out, they have to be replaced. Forklift101. provide hydraulic pump components for all makes and models for inexpensive prices. The hydraulic pump and its components should be replaced by a professional mechanic with expertise in hydraulic pump replacement.