pto hydraulic pump rebuild kit free sample

Whether gear, vane, or piston pump, there may come a time when you have to replace your hydraulic pump. When your equipment isn’t working properly and you have narrowed the problem down to a hydraulic pump that needs to be replaced, what do you need to know?

The pump may simply be worn out—they do have a natural lifespan, as they are a wearable item in a hydraulic system. Although it is not possible to give an average lifespan given the different types of pumps and widely varying hours of operation; in general, you can expect many years of good operation from a hydraulic pump in most truck-mounted hydraulic systems. However, the life of a hydraulic pump might be much longer than what you are experiencing. Here are some questions you should ask:

Has the equipment been operating acceptably with this pump for a number of years without incident, and has the decline in performance been gradual over a longer period of time?

In this case, you’ll need to get the pump make and model number so that you can make sure that your replacement will be correct—either with an exact replacement or with another make that has the same operating specifications.

In any case, when replacing a failed hydraulic pump you will want to make sure to use this opportunity to also change out your hydraulic fluid (or at the very least use a filter cart and filter your oil). In the process of failing, your pump has introduced contaminants into your hydraulic system that you want to remove before they damage your new pump or any other hydraulic component. You will want to change your filter element(s) when you install your new pump, and then change it (them) out after a break-in period on your new pump.

If not, then let’s make sure there is not something else going on, or you may just find yourself replacing pumps frequently because the underlying problem hasn’t been addressed.

Input shaft is twisted/bcanroken: This occurs due to an extreme shock load to the pump. Typically, this happens when a relief valve is missing from the system, not functioning correctly, set to a much higher value than what the pump can withstand, or is too small for the system flow and thus cannot function correctly.

Shaft fretting:Fretting corrosion occurs under load in the presence of repeated relative surface motion, for example by vibration. Direct mount pump splines can be worn away. The solutions include:

Using larger pump and PTO shafts will not eliminate fretting, but may resolve the problem because of the increased metal available before the failure occurs.

Make sure that the pump is able to get a good flow of oil from the reservoir—pumps are designed to have the oil feed pushed to the pump by gravity and atmospheric pressure, not by “sucking” oil. If the oil level in the reservoir is lower than the inlet of the pump, or the run too long or uphill, oil may not flow adequately to the pump. You can check if the pump is receiving oil adequately by using a vacuum gauge at the pump inlet. For a standard gear pump, at maximum operating RPM, the gauge should read a maximum of 5 inches HG. Larger numbers will damage a gear pump, and if you have a piston pump, the maximum number will be lower for good pump life.

Over pressurization: Pressure relief settings may have been adjusted or changed, and are now higher than what the pump can withstand without causing damage.

Pumps don’t produce pressure, they produce flow and are built to withstand pressure. When the system pressure exceeds the pump design, failure begins—either gradually or catastrophically.

When installing the new pump, back all the relief settings off. Then with the use of a pressure gauge T’d in at the pump outlet, gradually adjust the pressure relief setting until a cylinder or motor begins to move. Once the cylinder has reached the end of its stroke, gradually increase the pressure relief setting until reaching the max system pressure (which would be the pressure rating of the lowest rated component in the system). Sometimes, if a pump has been replaced and is larger than the original (produces more flow), the relief may not be able to allow all the flow being produced to escape back to tank. When that happens, the relief valve is “saturated” and the effect is the same as having no relief in the system. Pressures can reach levels much higher than the relief settings and components can be damaged or destroyed.

Contamination: Over time, the system oil has gotten dirty or contaminated and no longer is able to lubricate the pump, or is carrying contamination to the pump.

Things like restrictions and blockages can impede the flow of fluid to your pump. which could contribute to poor fluid flow. Air leak in suction line. Air present in the pump at startup. Insufficient supply of oil in pump. Clogged or dirty fluid filters. Clogged inlet lines or hoses. Blocked reservoir breather vent. Low oil in the reservoir

Now that we’ve ensured that the directional control is not reversed, it’s time to check that the drive motor itself is turning in the right direction. Sometimes incorrect installation leads to mismatched pipe routings between control valves and motors, which can reverse the direction of flow. Check to see that the motor is turning the pump in the right direction and if not - look at your piping.

Check to ensure that your pump drive motor is turning over and is developing the required speed and torque. In some cases, misalignment can cause binding of the drive shaft, which can prevent the motor from turning. If this is the case, correct the misalignment and inspect the motor for damage. If required, overhaul or replace motor.

Check to ensure the pump to motor coupling is undamaged. A sheared pump coupling is an obvious cause of failure, however the location of some pumps within hydraulic systems makes this difficult to check so it may go overlooked

It is possible that the entire flow could be passing over the relief valve, preventing the pressure from developing. Check that the relief valve is adjusted properly for the pump specifications and the application.

Seized bearings, or pump shafts and other internal damage may prevent the pump from operating all together. If everything else checks out, uncouple the pump and motor and check to see that the pump shaft is able to turn. If not, overhaul or replace the pump.

If your pump is having problems developing sufficient power, following this checklist will help you to pinpoint the problem. In some cases you may find a simple solution is the answer. If your pump is exhibiting any other issues such as noise problems, heat problems or flow problems, you may need to do some more investigation to address the root cause of your pump problem. To help, we’ve created a downloadable troubleshooting guide containing more information about each of these issues. So that you can keep your system up and running and avoid unplanned downtime. Download it here.

No job is too big for FleetPride’s Fluid Power Centers. We handle everything from the design and fabrication on the entire Fluid Power system to full cylinder rebuilding. Our Fluid Power Centers have the latest tooling, training, and industry experts to keep your equipment running.