When to replace your hydraulic pump
A Hydraulic pump operating in ideal conditions can last a very long time. However, it is not always possible to maintain ideal conditions in your hydraulic system and sooner or later, your pump will require repair or replacement. But how do you know when that time has come?
If your Hydraulic pump has suffered a catastrophic failure it is already too late. Chances are that the fragments and debris generated from the pump’s final moments will have already passed through your system and damaged the remainder of your components. Thankfully, these failures are often preceded by a period of accelerated wear and decreased efficiency which can be measured to determine the health of your pump and its likelihood of failure.
Measuring Pump Leakage
The difference between actual flow and theoretical flow (for a given displacement and speed) from a pump exists as leakage. As the internal surfaces of a pump wear, clearances between sealing components will increase and allow more leakage flow to pass between them. This leakage also depends on the type of oil being used, its viscosity and temperature. Some pumps, such as gear pumps, will simply bypass (or leak internally into their own inlet). Others, such as piston pumps, will leak externally into their housing or case which is routed back to the reservoir.
Measuring the actual flow with a flow meter and dividing this by the theoretical flow will give you a volumetric efficiency which can be compared against manufacturer’s published specifications for your pump. This will give instant feedback on the condition of your Hydraulic pump. If your pump’s efficiency is significantly lower than its factory specifications, then it is probably time for a pump repair or replacement.
On the other hand, if you cannot identify your pump or its displacement, you can still gauge its condition by taking multiple flow rate measurements over a period of time. If you notice any unusual or rapid decreases in performance over a couple of measurements then it may also be time for replacement.
There are easier ways to take these measurements. For many systems, the flow rate will have a direct impact on the speed of its actuators such that any decrease in pump efficiency will be manifested in a decrease in actuator speed. For piston and other pumps which leak into their housing or case, leakage flow from these lines is usually much easier to measure as the flow rate is significantly lower. Monitoring contamination in these lines also gives a good indication of the pump’s health as the products of pump wear often end up in its case.
Berendsen Fluid Power has nine branches nationwide which can assist in diagnosing pump issues and can provide service and repair of all varieties of Hydraulic pumps. Berendsen is also a distributor of a wide range of Hydraulic pumps from Eaton Hydraulics, and is a leading source for Danfoss, Rexroth, Dennison and Parker pumps.