This is a Rexroth A6VM variable displacement axial piston motor, the hydraulic unit specified for the SANY SR100 rotary drilling rig. It turns oil flow into the torque that drives the drill string, and when it fails the rig stops where it stands. We work as crane parts suppliers to rig fleets, workshops and parts traders, and this is one of the references we are asked for most often when a rotary drive gives up on site.
As construction machinery spare parts go, this one lives in the hardest-working corner of the machine: continuous load, dust, heat and vibration, with oil that is only as clean as the last filter change. A replacement hydraulic piston motor therefore has to match the original in displacement and control behaviour, not just in bolt pattern, or the rig will feel wrong long before anything visibly breaks.
The Rexroth A6VM motor is supplied complete and fully assembled — not an exchange core, not a rebuild. It sits in our crane spare parts range next to the pumps, valves, hoses and filters that share the same circuit, so a hydraulic repair can be planned and shipped as one order instead of three.
| Motor type | Rexroth A6VM axial piston motor, variable displacement |
| Model reference | A6VM250HD2D/63W2-VZB020 |
| Machine fitment | SANY SR100 rotary drilling rig |
| Nominal size class | 250 |
| Condition | 100% new, factory tested |
| Body material | High-strength steel |
| Finish | Matte grey paint |
| Input shaft | Splined |
| Mounting | Flanged face with through-holes |
| Identification | Rexroth nameplate with barcode and printed markings |
The complete code on the nameplate is A6VM250HD2D/63W2-VZB020. Read it exactly as printed: the characters after the displacement figure describe the control and mounting variant, and one different letter is usually a different motor. Photograph the plate rather than copying the number by hand — the barcode and printed markings beside it help confirm which line you are looking at.
A variable displacement motor and the unit coming off can share a flange and shaft and still behave differently, so before we confirm a match we look at the code on your plate, the machine model and serial, and the mounting arrangement on the unit coming off. That last point matters on mixed fleets: a motor that suits a rotary rig is not automatically right for the mobile crane parts book, even when the family name is the same.
It also helps to know what the motor is not responsible for. If the rig loses power but the motor turns freely on a bench, the fault usually sits upstream — in the pump, the control valve or the crane electrical components that command the drive. Checking those first saves a return trip.
| What you are comparing | This Rexroth A6VM250 motor | Where a cut-price lookalike saves money |
| Condition | A new, fully assembled unit — never a rebuilt core, never a resealed exchange motor | A resealed core or a used take-off that has been cleaned, repainted and re-plated |
| Control and mounting variant | Built to the control and mounting variant printed in the code, so this variable displacement motor holds torque and travel speed the way the SR100 circuit expects | Matched on family name and flange only; a different control setting makes the drive feel wrong from the first shift |
| Material | High-grade steel body and internals chosen for shock loads and continuous duty | Lighter castings and thinner internals that come back as a second failure within months |
| Testing | Functionally tested before it is packed, with test documentation issued against the reference | Leak-checked only in the simplest cases, and seldom with paperwork you can file |
| Identification | Original Rexroth nameplate carrying the full code, the barcode and printed production markings | Plate missing or re-stamped, so the next replacement starts from zero |
| Packing | Secure plywood crate with the spline and ports protected through export handling | Carton or open frame; grit reaches the rotating group before the motor is even bolted on |
| Backup | 2500 working hours or one year of cover, and a reference we can still match for spares years later | Sold as seen, with no support once the crate is open |
Not sure which part fits your machine? Send the part number, the machine model, and a photo of the nameplate or the worn item, and our engineers — each with more than ten years in the construction machinery business — will confirm the correct reference and quote it. We advise on installation, help trace faults, and answer technical questions before and after dispatch. Since 2017 we have built this support on a supplier network covering FUWA, SANY, XCMG and ZOOMLION, so older and hard-to-find references can usually still be sourced.
If the nameplate on the unit you are removing reads A6VM250HD2D/63W2-VZB020, this is the direct replacement. Send a photograph of that plate together with the machine model and serial, and we will confirm the variant before you order — the mounting and control details are what decide the match, not the family name alone.
Only where the parts book for that machine lists the same reference. The A6VM family turns up on several crane and rig drives, and we handle crawler crane parts requests for the same machines regularly, but fitment is settled by the code on your nameplate and the mounting on the unit you are replacing.
New. It is not a rebuilt core, not a resealed exchange unit and not a used take-off. The Rexroth nameplate and its printed markings are intact on the housing, which is usually the quickest way to tell a new unit from a dressed-up one.
The hydraulic piston motor uses a splined input shaft and a flanged mounting face with through-holes, so the existing coupling and fasteners can normally be reused. The body is high-strength steel with a matte grey painted finish. Compare the flange and spline against your own unit before ordering, especially if the drive has been repaired or modified in the past.
In three stages. A sample is approved and tested before production, inspections run during assembly, and every unit gets a full functional test with documentation before it is packed for dispatch. Anything that fails a stage does not go into a crate.
Alongside this unit we supply the rest of the hydraulic circuit — pumps, valves, seal kits and filters — as part of the same crane spare parts range for SANY, FUWA, XCMG and ZOOMLION machines.
On the electrical side, monitors, controllers, sensors, cables and other crane electrical components for those machines come through the same route, so a repair does not have to be split between several suppliers.
Because a low-cost substitute usually announces itself as a second failure. As crane parts suppliers we are judged on whether the machine goes back to work, so we send the reference that matches your plate rather than the nearest-looking unit on the shelf.
The Rexroth A6VM motor is built and tested to OEM-compatible standards and is sold as construction machinery spare parts for machines that run hard every day — not as a light-duty substitute for occasional use.
Most of what we ship goes into construction: rotary drilling rigs, crawler cranes, excavators and concrete pump trucks. The same hydraulic references also appear in agricultural equipment such as harvesters and tractors, and in specialised automotive hydraulic units, so if your machine sits outside the usual list it is still worth asking.
Start with the oil and the pressure: a restricted suction line or a tired pump will starve a healthy motor and imitate a motor fault. Then check the control side — a drive change can disturb the calibration of the crane load indicator and limiter, so have those verified before the rig returns to lifting or drilling.
