A7VO and A8VO Series Rotary Groups and Spare Parts
A7V A7VO and A8VO bent axis rotary groups and spare parts in sizes 28 to 1000 for excavator and heavy mobile main pumps.
Product Overview
A7V, A7VO and A8VO are bent axis pumps. The A8VO is the twin unit found as the main pump on many excavators, and the A7VO is the single unit used on heavy mobile and industrial machines. Both put very high load on the block face and the valve plate, so those two parts set the life of the pump. We machine complete rotary groups, cylinder blocks, piston sets, valve plates and drive shafts across sizes 28 to 1000.
| A7VO | 28 56 63 80 107 160 200 250 355 500 |
|---|---|
| A7V | 28 55 80 107 125 160 200 250 355 500 1000 |
| A8VO | 55 80 107 160 200 250 |
Key Benefits
- Supplied as a matched set so the block, shoes and valve plate run in together
- Same envelope and spline as the original, so the pump goes back on the machine unchanged
- Available for frames the original maker has moved off its list
- Twelve month warranty on the same terms as a new original part
Application Scenarios
- Excavator main pumps on machines from ten to fifty tonnes
- Drill rigs and piling equipment
- Heavy industrial power units
- Marine deck cranes and winch drives
Who It Is For
- Pump rebuild shops working to a customer deadline
- Plant and fleet maintenance teams
- Distributors carrying rotary group stock for local machines
- Machine builders needing a second source
Problems It Solves
- The excavator has lost power and boom speed under load
- The pump is noisy and the case drain flow has risen
- Only one section of a twin A8VO has failed
- The original rotary group price makes a repair hard to justify
Technical Features
- Cylinder block with sintered bronze running face bonded and machined after sintering
- Piston and shoe assemblies swaged and checked for shoe clearance
- Valve plate lapped to a mirror finish so the pair seals under pressure
- Retainer plate and ball guide matched to the block
- Splines and bearing seats ground after heat treatment
Specifications
Performance figures depend on the exact variant, so we confirm them against your model code rather than publishing a number that may not apply to your pump.
| Set contents | Cylinder block, pistons with shoes, retainer plate, ball guide, valve plate and spring set |
|---|---|
| Matching | Parts lapped and matched as one running set |
| Spline | To the original pattern, checked over pins |
| Marking | Neutral or your own part number on request |
| Packing | Oiled and vacuum sealed, boxed per set |
| Performance data | Confirmed against the full model code on your unit before quotation |
Materials
| Cylinder blocks | Case hardening steel with a sintered bronze running face, bonded and machined after sintering |
|---|---|
| Pistons and shoes | Case hardening steel with a bronze shoe face, swaged and hydrostatically balanced |
| Valve plates | Bearing steel or bronze faced steel depending on the frame, lapped to a mirror finish |
| Drive shafts | Alloy steel, carburised and hardened on the spline and bearing seats, ground on centres |
| Vanes and rotors | High speed tool steel and case hardening steel, hardened and ground on all working faces |
| Cam rings | Bearing quality alloy steel, through hardened then profile ground |
| Seals | Nitrile as standard, fluorocarbon or polyurethane on request for hot or fire resistant fluid duty |
Manufacturing Process
- Turning and millingBlanks are turned and milled from certified bar and forging stock on CNC machines.
- Heat treatmentCarburising, quenching, tempering or nitriding to the route the original part uses.
- GrindingBores, spline seats and running faces are ground after heat treatment so distortion is removed.
- Lapping and superfinishingValve plates, shoe faces and block faces are lapped so the pair seals under pressure.
- InspectionDimensions, hardness and surface finish are recorded against the drawing on a sampling plan.
- Assembly and testComplete pumps are built, run in and tested for efficiency, leakage and noise before packing.
Quality Control
- Incoming material certificates are checked against the grade called for on the drawing.
- Hardness is measured after heat treatment on every batch and recorded on the batch card.
- Critical bores and running faces are gauged against the drawing tolerance, not against a sample part.
- Mating parts are matched as a set so the block, shoes and valve plate run in together.
- Rebuilt pumps are bench tested for volumetric efficiency, external leakage and sound level.
- Parts are cleaned, oiled and vacuum sealed so they arrive without surface rust.
Certifications and Documentation
Supplied on request with an order. We do not claim approvals we cannot evidence.
| Material certificate | Mill certificate for the steel grade used in the batch |
|---|---|
| Hardness report | Surface and core hardness readings after heat treatment |
| Dimensional report | Measured values for the critical features named on the drawing |
| Test bench report | Flow, efficiency, leakage and sound readings for a rebuilt pump |
| Packing list and photographs | Carton contents and photographs of the packed goods before shipment |
Customization Options
- Shaft and splineKeyed, straight or splined shaft ends built to your sample or drawing.
- Port and mountingFlange, thread and mounting pattern matched to the pump already on the machine.
- Seal materialNitrile, fluorocarbon or polyurethane for hot oil, fire resistant fluid or low temperature duty.
- Rotation and displacementLeft or right hand rotation and the displacement code your circuit was set up for.
- Marking and packingNeutral packing, your own carton artwork and your own part number laser marked on the part.
Comparison With Other Products
| Point | A8VO | A7VO | A11VO |
|---|---|---|---|
| Layout | Twin bent axis unit | Single bent axis unit | Swash plate unit |
| Typical machine | Excavator main pump | Heavy mobile and industrial | Heavy work function |
| Sizes we build | 55 to 250 | 28 to 500 | 35 to 500 |
| Repairable per section | Yes, one side at a time | Single unit | Single unit |
Use Guide
- Record the full model code and the serial plate before stripping the unit.
- Measure the housing bore and bearing seats. A worn housing will kill a new rotary group.
- Fit the set complete rather than mixing new and used running faces.
- Renew the seal kit and the shaft bearing at the same time.
- Flush the circuit, prime the case with clean oil and run in at low pressure.
Product Photographs
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Frequently Asked Questions
Can one half of a twin A8VO be rebuilt on its own?
Yes. Each section has its own rotary group and can be repaired separately, although we usually recommend inspecting both.
What causes high case drain flow?
Worn shoe faces and a worn block face let oil past into the case. Measuring case drain flow is the quickest way to judge internal wear.
Do you supply the drive shaft and bearings?
Yes. Shafts, bearings, retainer plates and seal kits are all available.
Are A7V and A7VO parts the same?
They share a family but the controls differ. Give us the full model code so we quote the right variant.
How is the set packed?
Oiled, vacuum sealed and boxed as one set so it stays clean until it reaches the bench.
Send Us the Model Code and We Will Quote
Tell us the model code stamped on the pump, the quantity and your delivery port. A quotation with lead time usually comes back within one working day.