Measuring the Axial Clearance of a Gear Pump
The gear pump is one of the most popular types of hydraulic pumps used in hydraulic systems. It consists of two inter engaged, internal and external gears, rotating in opposite directions within a sealed chamber or housing. The fluid to be pumped is drawn from the inlet port and forced through the outlet port by the meshing action of the gears. To avoid premature failure due to metal-to-metal contact between the gears, a certain amount of axial clearance must be present in the pump. This axial clearance, or gap, is designed to provide a sufficient cushion of lubricating liquid slippage between the mating gears.
Measuring the axial clearance of a gear pump is an important maintenance task, as any changes in the clearance can reduce the lifespan of the gear pump and lead to premature failure. Since the gear pump is typically mounted in the engine block or other inaccessible locations, the clearance can be difficult to measure. However, by following several simple steps and using various measuring tools, it is possible to determine the axial clearance of a gear pump accurately.
The first step in measuring the axial clearance of a gear pump is to locate the pump. Depending on the make and model, gear pumps may be mounted in various locations on the engine block or other parts of the hydraulic system. Once the pump is located, it should be disassembled so that the gears and other components can be accessed for measurement.
When the gear pump is disassembled, the next step is to measure the OD (Outside Diameter) of the mating gear teeth at eight different points around the circumference. This should be done using a vernier caliper to ensure accuracy. The measurements should be made from a point on the outer edge of the tooths flute to the center of the circumference. The average of these eight measurements can then be used to determine the OD of the gear teeth.
Once the OD of the gear teeth has been determined, it is then possible to measure the ID (Inner Diameter) of the mating gear teeth. This should be done using a bore gauge and reference gauge. The bore gauge should be inserted into the gear teeth until it rests on the bottom of the flute and then the reference gauge should be slid against the outside of the bore gauge. The difference between the OD and the ID of the gear teeth can then be used to calculate the axial clearance.
If the axial clearance is larger or smaller than the recommended value, the clearance should be adjusted. This is usually done by adding or subtracting shims from the gear teeth or by components replacement. Once the pump is reassembled, the axial clearance should be remeasured to ensure it is set correctly.
Measuring the axial clearance of a gear pump can be an intimidating task, but if done correctly, it can help prolong the life of the pump and ensure that it operates optimally. By following the steps outlined above and using appropriate measuring tools, it is possible to accurately and precisely measure the axial clearance of a gear pump. This can help prevent costly and unexpected repairs and ensure that the pump is correctly calibrated.
