WIBAKO overhauls Bosch Rexroth / Hydromatik axial piston pumps and hydraulic motors. These are some of the most widely used axial piston units. You will find them in excavators, loaders, cranes, rollers, pavers, forestry and agricultural machinery, as well as in truck bodies and municipal vehicles. Below we describe the most common series and their typical faults. We also explain how to diagnose a problem and how a pump or motor is rebuilt and tested after repair.
Overview of Rexroth pump and motor series used in machinery
A Rexroth type code tells you straight away which design you are dealing with. The characters after the “A” and the digit define the type (e.g. 10V – variable displacement pump with a swashplate). The next letter indicates the circuit: O – open circuit, G – closed circuit, M – motor. The number is the displacement in cm³/rev.
A10VO / A10VSO – variable displacement pump for open circuits
A swashplate axial piston pump built in a wide range of sizes. It supplies the working hydraulics of wheeled and tracked excavators, loaders, cranes and drilling rigs, as well as industrial systems. The most common controllers are:
- DR – pressure controller,
- DFR/DFR1 – pressure and flow controller (load sensing),
- DFLR – as DFR, with additional power control,
- hydraulically or electrically controlled versions.
A4VG – pump for closed-circuit hydrostatic drives
A typical travel drive pump: rollers, pavers, telehandlers, combine harvesters, truck mixers and forestry machines. It has an integrated charge (boost) pump, high-pressure relief valves and a charge pressure valve. Control options include EP, HD, DA and ET. An example from our range: Rexroth A4VG56ET5D1/32R pump.
A10VG – smaller closed-circuit pump
The counterpart of the A4VG for lighter machines: compact rollers, loaders and smaller agricultural and municipal machines. Popular sizes include the A10VG28, A10VG45 and A10VG63. Typical faults are similar to those of the A4VG: wear of the rotating group, the charge pump and the valves.
A11VO / A11VLO – high-pressure pumps for open circuits
Used in medium and large excavators, wheel loaders and cranes. The A11VLO version has a built-in charge impeller, which allows it to run at higher speeds without cavitation. They are often fitted with a power controller (LR) and additional control functions. Example: Rexroth AA11VO130LG2S/10R pump.
A6VM – bent-axis variable displacement motor
A motor for travel drives (wheeled excavators, loaders, road machinery) and winches. Variable displacement provides high starting torque and high travel speed. Control options include HD, EP and HA (automatic, pressure-dependent).
A2FO / A2FM – fixed displacement pumps and motors
A simple and robust bent-axis design. The A2FO is found, among other places, in truck bodies (loader cranes, hook lifts, tippers). The A2FM serves as a motor for fans, winches and auxiliary drives.
We also overhaul other series: A2FE, A4FO, A4V(S)O, A6VE, A7VO, A8VO and A11VG.
Rexroth A10VO100 – what to look out for
The A10VO100 is one of the Rexroth pumps most frequently replaced and rebuilt. It comes in many variants that look alike from the outside but are not always interchangeable. When ordering a pump or parts, check the full type code on the nameplate, e.g. A10VO100DFR1/31R-VSC62N00:
- DFR1 / DFLR / FHD – controller type (determines how flow and pressure are controlled),
- 31 – design series,
- R / L – direction of rotation (clockwise/counter-clockwise),
- further letters – seal material, shaft (splined, keyed), mounting flange and ports,
- N00 / K04 etc. – no through drive or through drive type (option to add a second pump),
- material number R9… – the most reliable identifier when selecting a replacement.
A mistake in rotation direction, shaft or controller means the pump either cannot be fitted or will not control the system correctly. Our range includes the Rexroth A10VO100DFLR R992002142 pump and other A10VO100 variants. Availability of a specific version is best confirmed by phone or email.
Typical Rexroth pump faults and their symptoms
- Loss of output, slow attachment or travel movements – wear of the cylinder block and valve plate, play in pistons and slippers, internal leakage.
- Increased case drain leakage – one of the best indicators of rotating group wear. Measuring the flow in the drain line lets you assess the pump's condition without removing it.
- Noise, whining, metallic sounds – cavitation (low oil level, clogged suction strainer, air leak on the suction side), damaged bearings or slippers.
- Oil overheating – high internal leakage, incorrect controller or valve settings.
- Pressure fluctuations, “hunting” flow – worn controller spool, contaminated control orifices, damaged control piston.
- Leak at the shaft – worn shaft seal, often caused by excessive case pressure (blocked drain line).
- Metal particles on filters and the magnetic plug – advanced wear. The machine should be stopped before the pump seizes.
The most common cause of failure is contaminated oil and neglected filtration. Less often, assembly errors are to blame, e.g. starting the pump without filling the housing with oil.
Diagnostics before removal
Before a pump goes for overhaul, it is worth confirming that it really is the source of the problem. We measure working and pilot pressures, case drain leakage and oil temperature, and we also check the filters and an oil sample. Poor machine performance may be caused by a faulty control valve, relief valve or hydraulic motor. Sometimes even a loss of diesel engine power is to blame. We described a case where a pump repair revealed another problem in the system in our article on servicing a Sennebogen 730E.
How a Rexroth pump or motor is rebuilt
- Disassembly and cleaning – stripping down into parts and assessing wear patterns, which often point to the cause of failure.
- Measurements – cylinder block, valve plate, pistons with slippers, swashplate, retaining plate, bearings, shaft.
- Machining or replacement – lapping the cylinder block and valve plate surfaces, replacing the piston set, bearings and seals, and the shaft if necessary.
- Controller repair – checking the spool and sleeve, cleaning passages and orifices, replacing worn components.
- Assembly and testing – every unit is checked on a test bench after overhaul. We verify flow, pressure and leakage and set the controller according to the type code.
We write more about what wears in piston pumps and how often they should be serviced, using the example of rebuilding a DPVO 165 pump from a Liebherr A316. We follow a similar process for Liebherr hydraulic pump and motor overhauls.
Rebuild or replace?
A rebuild is usually cost-effective when the housing, cylinder block and shaft can be machined or repaired. If the pump has seized and the housing has cracked, a reconditioned or used unit is often the better option. Whatever you choose, after a major failure you must flush the system, change the filters and oil and check the other components. Metal debris from a damaged pump will quickly destroy a new one.
Parts, reconditioned and used units
We are steadily expanding our stock of spare parts for Rexroth pumps and motors, including less common models. We offer reconditioned units which, when time is critical, we can configure to reduce machine downtime. We also have used components whose condition we confirm by inspection. To check availability of a model or arrange a repair, please get in touch – ideally with the full type code from the nameplate.
Frequently asked questions
How can I tell if a Rexroth pump is worn without removing it?
The best indicator is measuring case drain leakage in the drain line, supplemented by measuring working and pilot pressures and oil temperature. It is also worth checking the filters and magnetic plug for metal particles.
Are Rexroth A10VO100 pumps with different controllers interchangeable?
Not always. Variants differ in controller (e.g. DFR1, DFLR, FHD), direction of rotation, shaft, flange and through drive. The most reliable way to select a replacement is by the full type code and the R9… material number on the nameplate.
What information should I provide when enquiring about repairing or buying a Rexroth pump?
The full type code from the nameplate, the R9… material number and the machine model. For a repair, a description of the fault symptoms is also helpful.
Does the system need flushing after a hydraulic pump failure?
Yes. After a major failure the system should be flushed, the oil and filters changed and the other components checked, because metal debris from the damaged pump can quickly destroy a new or rebuilt unit.
Do you also repair Bosch Rexroth hydraulic motors?
Yes, we overhaul both Rexroth / Hydromatik pumps and hydraulic motors, including the A6VM, A2FM, A2FE and A6VE.
