Trying to determine what is wrong with Rexroth gear pumps can be very challenging when they are not working well. The aim of this article is to assist you in troubleshooting a Rexroth Gear Pump so that it works without any interruptions.
Pump does not deliver / suck
Rexroth gear pumps are a reliable and efficient way to move water and oil. However, if the pump does not deliver or suck, there may be a problem with the pump. In this article, we will discuss some common Rexroth gear pump troubleshooting tips.
Your Rexroth gear pump is probably not doing its job of pumping or suctioning in case of anything going wrong with it. This problem can often be resolved without opening up the pump or replacing any parts though. Below is troubleshooting advice for Rexroth gear pumps:
1-Ensure that power is available for the pump
2-Check if there are things blocking the flow of water or oil. Before the pump can function properly, these obstructions must be cleared away.
3-Carefully clean all parts of the pump using a solvent or degreaser which is clean; ensure that all debris and oils have been removed.
4-Make sure that all seals on the pump are in good condition and adequately greased.
Delivery pressure too low
Rexroth gear pumps are reliable and efficient tools which increase production efficiency. However, their gears can spoil if the delivery pressure is too low. It’s thus vital to establish where in the system this problem is occurring.
The case could be a faulty valve or diaphragm at the pump outlet if the pressure here is low. The other reason may be a filter orifice becomes clogged. Now that you have known what the problem is, you can replace the damaged part to rectify it.
Pump is too loud
In case of high noise coming from your Rexroth gear pump, it is better to begin with troubleshooting the unit. Here are some common causes and solutions:
1.Blockages in the circulation system should be checked. When the pump runs all the time but cannot generate enough pressure required for it to meet an expected level, debris or silt may collect in the path of flow hence causing a noisy sound. To clear away any clogs on a line, use a shop vacuum or air compressor then look for leaks in valves and fittings.
2.Wear out parts must be replaced. Also worn components such as seals or bearings could make a gear pump too noisy. Before buying another pump, ensure that you replace these components if necessary.
3.Ensure there is enough oil level. With time, oil gets contaminated and makes a gear pump very noisy. Periodically check the level of oil and add if necessary in order to maintain sufficient pressure required for its operation
Interfaces not tight
Often, Rexroth gear pumps are applied in industrial and commercial applications. When they are used properly, these pumps can provide high pressure and flow rates. Otherwise, if a pump’s interface with its casing is not good enough water may enter the machine leading to failure.
One common problem with Rexroth gear pumps is that the interface between the case and pump can become loose over time. Consequently, this can result in water seeping into the pump and causing it to fail. Therefore, it is crucial to make sure that you seal your casing as tight as possible when connecting it to your pump. For any signs of an intrusion of water into your Rexroth gear pump , please contact our team for assistance . We shall be able to diagnose the problem for you and guarantee that your pump still functions perfectly well.
Pressure peaks over >350 bar from system
Industries like those in chemical, gas and oil, food processing, pharmaceuticals among others widely use the Rexroth gear pumps. This is as a result of their high efficiency and durability. On the other hand, even some of the best geared pumps may develop some problems when they are not operated properly.
One problem that is commonly faced by most Rexroth gear pumps is pressure peaks beyond > bar from the system. In this occurrence, an overloaded system can damage a pump. By monitoring pressure readings all over the system and taking necessary steps whenever required can prevent such a condition from happening again.
The system interfaces cannot be mounted
Rexroth gear pumps are among the most widely used pumps globally. They are found in various application areas from agriculture to industry. However one shortcoming that is common with Rexroth gear pumps is their difficulty in terms of troubleshooting.
One of the problems that can be encountered when dealing with Rexroth gear pumps is difficult to troubleshoot. This implies that this system has no interfaces for mounting. Thus there will be no access into pump for diagnosis and repair purposes. As a result, it may become tough to get the pump up and running properly.
1, Isolating problem is crucially important i.e. any other equipment affecting the pump must be turned off.
2, Correct measurements also matter a lot i.e. a device which can accurately measure pressure and flow rates should be used.
3, Finally, understanding the mechanics behind the functioning of this pump becomes vital; know how it works so as to address any occurring hitches
Viscosity <10 mm2/s
The Rexroth gear pumps are among the most sold pumps. They transfer fluid from one point to another. There is a wide variety of sizes and capacities of Rexroth gear pumps, which makes them ideal in different applications.
Viscosity < mm/s is one common problem experienced by users using Rexroth gear pumps. This is when liquid flow through the pump is either too fast or too slow. If not rectified this can cause major issues.
According to professionals, varied diagnostic tools must be employed for the identification and correction of viscosity < mm/s defect on the gear pumps by Rexroth. These include flow meters as well as pressure gauges and differential pressure gauges.
In order to increase the rate at which fluid flows through the pump, corrective actions should be taken as suggested by experts after establishing the problem. Valve adjustments, motor size changes or part replacements might be some of these measures.
Viscosity >300 mm2/s
Rexroth gear pumps exist in various configurations, as regards the type of mechanism involved in their operation; examples include, reciprocating gear pumps and rotary gear pumps. As for the first type –reciprocating gear pump, it is distinguished by the fact that it uses pistons to move the fluid material. Likewise, rotary gear pumps are installed with rotating gears that help to shift the fluid materials.
Gear pumps typically can be grouped into two categories basing on their principles of operation i.e. positive displacement pumping and displacement pumping. This type of pump operates through a positive displacement principle hence uses an expansion chamber that increases the pressure inside the pump. Besides these others work on displacement pumping principle where they use a chamber inside them which decreases or lowers down pressure within the pump.
Moreover, they can be classified according to stroke; short stroke as well as medium stroke and long stroke. On the other hand, short strokegear pumps have a smaller stroke in comparison with both medium and long strokegear pumps because these types deliver more fluids per unit time than any other kind of similar devices.
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Volumetric or mechanical efficiency is not achieved
It is not possible to achieve volumetric efficiency in the case of Rexroth gear pumps. One reason behind this is that the mechanical efficiency depends on both the number of strokes per minute (spm) and the volumetric efficiency which depends on actual displacement. Therefore, while using gear pumps, it is necessary to pay attention to these two factors.
Admissible level of contamination of the hydraulic fluid has been exceeded
There are various industrial and commercial applications where Rexroth Gear Pumps are used for the circulation of hydraulic fluid.Whenever a hydraulic fluid leaks out or if there is any doubt about its quality, one can say that the permissible contamination level has been exceeded.
To prevent any possible problems and to get the best performance from your Rexroth Gear Pump, it is necessary to check how much pollution exists in the hydraulic fluid. This guide will explain how to measure admissible contamination level.
1.Use either an appropriate brush or vacuum cleaner in order to remove debris and all other foreign objects which may be around the gear pump.
2.Examine the gear pump housing for any sign of leakage or damage; if any indication is found, replace the gear pump housing without delay.
3.The contaminated state of hydraulic fluid should be checked immediately upon perceiving during inspection process; thereafter change it promptly if evidence of contamination has been detected.
Wrong direction of rotation of the drive motor
In agricultural and industrial applications, Rexroth gear pumps are frequently used. Normally these drive motors rotate in clockwise direction, but this can be changed with the right tool. If the motor is turning in the wrong direction, there may be damage to the pump or its components. Most of the time reversing the motor rotation will resolve the problem.
Protective motor switch is activated
The water pump’s breakdown is usually indicated by a triggered safety switch. Then, if you have previously undergone a maintenance service of your water pump before and you are familiar with its operations, you can verify if there is anything stuck between the switch in order to confirm. If it is not blocked then you may have to replace the motor. Look for any signs of excessive heat on the motor. The motor is positioned at the back of the pump which has wires that go through metal sleeve leading to it. Any indications of an overworked engine must be substituted immediately.
Input speed too high/too low
The pump may not keep up with the demand if it is overloaded due to a very high input speed. Conversely, insufficient input speed may cause the pump to be incapable of moving enough air or fluid so as to meet demand.
Air inlet through the output side
Check the following if there is no air inlet flow through the output side of the Rexroth gear pump:
Make sure that Venturi tube is in the right position and is fitted to connect it with intake side of pump.
1.Ensure that all air valves are tightly closed.
2.Confirm that suction tube is well stuck to the pump.
3.See whether both suction and discharge tubes are secured to the pump.
4.Establish whether an air intake pipe has been firmly connected to an input valve which lies at a remote point.
Fluid leakage
Gear pump failure calls for troubleshooting the problem and determining what caused it. Rexroth provides multiple gear pumps for different applications which makes it essential to learn their usage and troubleshooting.
The common problem with gear pumps is the leaking of the fluid. Fluid leakage occurs when there are failed seals or gaskets that allow oil or water into the pump, causing damage. To detect fluid leakage, you should start by visually examining any signs of damage on the pump itself. Look at motor mountings or casing where there are patches of wetness and housing for any cracks. Whenever you notice these signs of damage, make haste to substitute this O-ring or piston ring.
If you do not notice any such defects, another explanation could be that there is a low oil pressure which has caused the pump to fail. Take an oil gauge or dipstick measure to ascertain its level on the engine block. Replace either an O-ring or a piston ring once you find out that the pressure is too low. If that does not work, use either a snake or manual vacuum cleaner to look for clogs in your oil line. In case none of these solutions works out, then your gear pump could be broken down and needs replacing with another one
Output flow is not achieved
In case the flow is not as required then there might be a problem with the pump. The following are some tips on how to troubleshoot the issue:
1.Make certain that the installation of the pump is right. Confirm if it is linked to the correct system and whether power is switched on.
2.Check connections for power supply. Ensure that they are tight and accurately positioned in relation to pump.
3.Inspect deteriorations or malfunctions of parts in the pump and repair where necessary or replace defective components.
4.Examine parameters used by a functioning pump, for instance, one can adjust them to know if it will work properly at any point.
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Permanent output pressure >315bar
Rexroth gear pumps are used in various industries to extract liquids and gases from tanks, pipelines, and other containers.
If you have a problem with your Rexroth gear pump, there are several things you can do to diagnose the issue. First, check the output pressure. See that the pump is providing enough pressure for it to work properly. If the output pressure is low you might require replacing or adjusting the setpoint on the pump.
On contrary, if output pressure is high in most cases then it may be due to a diaphragm or seal failure. In this situation, one has no option but replace new pump. Though an alternative way of reducing the output pressure would be by adjusting down the set point; this could also not effect any change thus leading you into buying another pump entirely
Wear caused by radial force on the shaft
The existence of a gear pump whose shaft has radial forces can contribute to wearing. Pump failure occurs when this wear is severe. The following are some tips for solving this problem:
1.Examine the teeth and shaft thoroughly concerning extreme wearing.
2.Investigate the presence of foreign objects or dirt on the gear wheels and/or shafts.
3.Find out whether there are tight tolerances between gears and shafts; otherwise, they might require a replacement.
Wear caused by axial thrust on the shaft
One of the ways in which Rexroth Gear Pumps wear is due to the axial thrusts on their shaft. The most prevalent form of wear is occurring from rubbing of teeth on the cam. Consequently, material will accumulate around it, thus causing its breakage. To prevent this, you should check out for the level of wearing and replace your cam if necessary.
Pump wear
Like any other mechanical device, the Rexroth gear pumps can wear down with continuous usage. The article will provide an explanation on some pump wear issues and how to correct them.
Incorrect fluid usage, incorrect assembly or installation, and corrosion are the most common causes of pump wear. Follow attentively the installation instructions provided by Rexroth pump to prevent wearing. Be sure you have compatible fluid to use with your pump as well as properly assembled and sealed system. Lastly, check if there are any signs of corrosion on the pump that you clean regularly. In case you notice wearing or damages, get in touch with Rexroth for replacement or repair services.
Troubleshooting Form
| Malfunction | Possible cause | Remedy |
| Pump does not deliver / suck | The pump is not bled | Bleed the pump |
| O-rings defective (wrong medium, damage to Install/replace with original O-ring the sealing, missing O-ring, wrong O-ring) | ||
| Sealing surfaces contaminated or damaged Ensure cleanness and integrity of the sealing surface |
||
| Coupling is missing and/or parts of the coupling are missing | Amend the coupling or coupling component | |
| See malfunction “Wrong direction of rotation of the drive motor” | ||
| See malfunction “Air inlet through the output side” | ||
| See malfunction “Back pump is blocked” | ||
| See malfunction “Back elements exceed maximum torque” | ||
| Delivery pressure too low | See malfunction “Inlet pressure <0.6bar” | |
| See malfunction “Admissible level of contamination exceeded” | ||
| See malfunction “Output flow is not achieved” | ||
| Pump is too loud | See malfunction “Interfaces not tight” | |
| See malfunction “Wrong direction of rotation of the drive motor” | ||
| Ambient temperature is below –20°C | Provide for suitable ambient temperatures | |
| Aspiration of air bubbles | Bleed the system | |
| Vortex generation in the suction area of the fluid tank | Check the filling level of the fluid tank | |
| See malfunction “Viscosity <10 mm2/s” | ||
| See malfunction “Viscosity >300 mm2/s” | ||
| Interfaces not tight | O-rings defective (wrong medium, damage to Use original O-ring the sealing, missing O-ring, wrong O-ring) | |
| Sealing surfaces contaminated or damaged Ensure cleanness and integrity of the sealing surface |
||
| Incorrect assembly (screws too long) | Assembly only by authorized, trained and instructed qualified personnel; only use original spare parts | |
| Combination part is not suitable | Observe the project planning information in RE 10227 | |
| Pressure peaks over >350 bar from system | Feedback from hydraulic system | In the project planning, observe the admissible pressure peak in RE 10227 |
| Integrate pressure control valves | ||
| The system interfaces cannot be mounted | Wrong connection flanges/screws suction port and/or pressure connection selected | Observe the flange dimensioning in RE 10227 |
| Viscosity <10 mm2/s | Hydraulic fluid too hot | Information on hydraulic fluids in RE 90220; observe the project planning information in RE 10227; check the water content, viscosity, turbidity and smell on a regular basis |
| Shelf life of the hydraulic fluid is exceeded | ||
| Wrong hydraulic fluid filled in | ||
| Viscosity >300 mm2/s | Fluid temperature too low | Information on hydraulic fluids in RE 90220; observe the project planning information in RE 10227; check the water content, viscosity, turbidity and smell on a regular basis |
| Wrong hydraulic fluid filled in | ||
| Thickening due to mixing | ||
| Volumetric or mechanical efficiency is not achieved | See malfunction “Viscosity >300 mm2/s” | |
| See malfunction “Viscosity <10 mm2/s” | ||
| See malfunction “Output flow is not achieved” | ||
| Operation projected with too low and/or too high speed | Observe the project planning information in RE 10227 | |
| See malfunction “Admissible level of contamination of the hydraulic fluid exceeded” | ||
| Mixing of different fluids | Observe the information on hydraulic fluids in RE 90220 | |
| Admissible level of contamination of the hydraulic fluid has been exceeded | Fluid aging and abrasion from system | Check the fluid contamination according to the maintenance schedule |
| Insufficient filtration | Observe the project planning information in RE 10227 and check according to maintenance schedule | |
| Unexpected inlet of contamination (e.g. in case of fluid exchange) | Provide for a clean environment, filling only via filter | |
| Wrong direction of rotation of the drive motor | Drive motor corrected incorrectly | Assembling only by authorized, trained and instructed experts |
| Check the direction of rotation in case of re- commissioning after mains separation | ||
| Protective motor switch is activated | Drive motor too weak | Observe the information on the required drive power in RE 10227 |
| See malfunction “Wrong connection of the drive motor” | ||
| See malfunction “Pump wear” | ||
| Input speed too high/too low | Motor projected with too low and/or too high speed | Observe the project planning information in RE 10227 |
| Air inlet through the output side | O-rings defective (wrong medium, damage to the sealing, missing O-ring, wrong O-ring) | Use the original combination part set, replace the seals |
| Fluid leakage | Tank hangs too high | Observe the project planning information in maintenance and commissioning of hydraulic components RE 07800 / RE 07900 |
| Fluid level too high | ||
| Pre-charged fluid tank (too high pressurized) and/or pre-filling pump | Observe the project planning information for pre-charged tank and/or pre-filling pump | |
| Defective seal | Exchange the damaged O-ring | |
| See malfunction “Interfaces not tight” | ||
| Inlet pressure <0.6bar | Faulty dimensioning of the suction line (length, cross-sections, angle) | Observe the project planning information in RE 10227 |
| Speed too high | In the project planning, observe the maximum speed | |
| Foreign body in the suction channel | Remove the foreign body | |
| Air pressure too low In the project planning, observe the absolute (also tank without pressure compensation) pressure | ||
| Inlet pressure >2bar | See malfunction “Fluid leakage” | |
| Output flow is not achieved | Pump sucks in air | Check the level in the fluid tank and correct it, if necessary Observe the information on the design of the lines in hydraulic trainer, volume 3 and project planning information |
| Input speed too low | In the project planning, observe the characteristic curve average values drive power in RE 10227 | |
| See malfunction “Admissible level of contamination of the hydraulic fluid exceeded” | ||
| See malfunction “Pump wear” | ||
| Permanent output pressure >315bar | Line cross-section too little | Observe the information on the design of the lines in hydraulic trainer, volume 3 and project planning information |
| Flow resistances too high | ||
| Admissible load exceeded | For limiting the operating pressure and for the solenoid-actuated discharging of the operating pressure, install a pump safety block. In doing so, observe the information in RE 10227 | |
| Wear caused by radial force on the shaft | Incorrect installation | Observe the installation information |
| Unsuitable parts | use only an original combination part set | |
| Tightening torque for the screws is too low | Observe the tightening torques in the installation information | |
| See malfunction “Pump wear” | ||
| Wear caused by axial thrust on the shaft | Incorrect installation | Observe the installation information of the coupling manufacturer |
| Unsuitable parts | use only an original combination part set | |
| See malfunction “Pump wear” | ||
| Pump wear | Contaminated or wrong operating medium | Filter or exchange the operating medium, perform regular controls. |
Summarize
Rexroth gear pumps are one of the most popular types of pumps used in industry. When they encounter trouble, troubleshooting can be difficult. This blog section will provide a step-by-step guide for troubleshooting Rexroth gear pumps.
Related Reading：
Hydraulic Piston Pump Troubleshooting
Hydraulic Gear Pump Troubleshooting
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