Vickers Pump Compensator Settings and Adjustment
On a Vickers variable piston pump the compensator is what caps system pressure by de-stroking the pump. Set it wrong and you either never reach working pressure, or you push the pump past what it was built for. The awkward part is that the safe range is not the same across the range. It changes with the series, and on some models it changes with the control code stamped into the model number.
The tables below come out of the Vickers service manuals for each series.
Work with a gauge, never by counting turns. These valves can usually be wound past the published limit. The manual for the PVQ45 says it plainly: the compensator pressure adjustment on a PVQ45C shall not exceed 2750 psi. The screw will go further. That is not permission.
Find your control code first
The compensator type is a field inside the model code, and it decides your range. Get this before you touch anything. If you are not sure how to read the code, start with how to identify a Vickers pump.
PVH series: PVH57, PVH63, PVH74, PVH81, PVH98, PVH106, PVH131, PVH141
| Code | Control | Setting range |
|---|---|---|
C |
Compensator | 140 to 280 bar (2000 to 4000 psi) |
CM |
Compensator, low pressure | 35 to 140 bar (500 to 2000 psi) |
IC |
CETOP 3 interface compensator | 20 bar factory differential setting. QI and QP models only. |
The field immediately after the control type in a PVH code is the factory compensator pressure setting, so a pump can arrive set anywhere inside its range. Do not assume it left the factory at maximum.
PVB series
| Code | Control | Setting range |
|---|---|---|
C |
Compensator | 250 to 3000 psi |
CM |
Compensator, low pressure | 150 to 1500 psi |
PVQ series: PVQ10, PVQ20, PVQ25, PVQ32, PVQ40, PVQ45
| Code | Control | Setting range |
|---|---|---|
C** |
Standard compensator | 350 to 2750 psi. The two digits are the setting in tens of bar, running 02 to 19. |
CM** |
Low pressure compensator | 350 to 1500 psi. Digits run 02 to 10. |
C**V**B |
Compensator with load sensing | As C**, plus a load-sense differential. |
CD** |
Electric dual range compensator | Two settings, selected electrically. |
Worked example straight from the manual. C21V11B on a PVQ25 means a compensator set to 207 bar with an 11 bar load-sense differential. The same pattern on a PVQ40 reads as 210 bar. So the digits after the C are not a part number, they are the pressure, in tens of bar.
PVE series
| Model | Compensator setting | Notes |
|---|---|---|
| PVE27 | 25 to 250 bar (up to 3625 psi) | Control option V is load sensing pressure limiting. |
| PVE19, PVE21 | See the service drawing for your build | The compensator is lockwired after setting. The manual instruction is to adjust the compensator, then drill through with a 0.1089 drill for the wire. |
Setting the compensator
- Write down what it is set at now. Run the system, deadhead it against a closed function and note where the gauge settles. If this goes wrong you want the original number.
- Warm the oil. Cold fluid reads high and behaves differently. Set at operating temperature or you will be setting it twice.
- Check the system relief first. The compensator has to be set below the relief valve, or the relief dumps before the pump ever de-strokes and the compensator can never control. This is the most common reason an adjustment appears to do nothing.
- Confirm your range from the tables above using the control code on the nameplate, not the series alone. A PVH with a CM control tops out at 2000 psi, not 4000.
- Loosen the locknut, holding the screw so it does not turn as the nut breaks free.
- Adjust in small steps against the gauge. A quarter turn at a time, letting the reading settle. Clockwise raises the setting on these controls, but confirm it from the gauge on your first movement rather than trusting the rule.
- Lock it and re-check. Tightening a locknut moves the screw more often than not. On a PVE19 or PVE21, remember the compensator is lockwired, so it needs re-wiring after the adjustment.
When the compensator is not the problem
A compensator that will not hold, or a pump that will not reach its setting, is usually reporting a fault rather than causing one.
| What you see | What it usually means |
|---|---|
| Pressure builds then collapses under load | Rotary group wear. Measure case drain flow against the rated figure before touching the control. |
| Adjustment does nothing at all | System relief set below the compensator, so the relief is controlling instead. |
| Setting drifts after being locked | Contamination in the control spool, or a tired compensator spring. |
| Pump stays loud and hot at full pressure with nothing moving | Pump is not de-stroking. Control fault, or a stuck spool. |
| Works cold, fails warm | Internal leakage. Hot oil is thinner and slips past worn clearances. |
More on each of those in hydraulic pump not building pressure and why is my hydraulic pump overheating. If it turns out to be wear, our guide to what a rebuild actually costs covers which bracket you are in.
Parts by series
- PVH57 / PVH63
- PVH74 / PVH81
- PVH98 / PVH106
- PVH131 / PVH141
- PVB5
- PVB10
- PVB20
- PVB45
- PVB90
- PVQ10
- PVQ20
- PVQ32
- PVQ45
- PVE19
- PVE21
- Piston pump seal kits
Need a compensator, a spring or a control assembly?
Send the full model code from the nameplate, including the control field. That is what tells us which compensator you have and which parts fit it. Over 13,000 Vickers line items, and most quotes go out the same business day.
Request a quote · (810) 882-1171 · info@restopower.com
Where to buy Vickers parts. Ships nationwide and worldwide from Lake Orion, Michigan.
Frequently asked questions
What is the pressure range of a Vickers compensator?
It depends on the series and the control code. On a PVH, a C compensator runs 140 to 280 bar (2000 to 4000 psi) and a CM runs 35 to 140 bar (500 to 2000 psi). A PVB C runs 250 to 3000 psi and a CM 150 to 1500 psi. A PVQ standard compensator runs 350 to 2750 psi. A PVE27 runs 25 to 250 bar.
How do I adjust a Vickers pump compensator?
Record the current setting, warm the oil to operating temperature, confirm the system relief is set above your target, loosen the locknut, then adjust a quarter turn at a time against a gauge until you reach the setting. Lock the nut and re-check, because tightening it usually moves the screw. Stay inside the published range for your control code.
What does the C or CM in a Vickers model code mean?
It is the pressure control type. C is the standard compensator and CM is the low pressure version, with a lower maximum setting. On PVQ pumps the two digits after the C are the pressure setting itself, expressed in tens of bar, so C21 is 207 to 210 bar depending on the frame.
Why does adjusting the compensator do nothing?
Most often because the system relief valve is set below the compensator, so the relief is capping pressure instead. Check the relief setting first. The compensator has to be set below the relief for it to control at all.
Can I set a Vickers compensator above its published maximum?
The screw will physically go further, but no. The PVQ45 manual states the compensator pressure adjustment shall not exceed 2750 psi, and the same principle applies across the range. Exceeding the published limit risks the pump and the rest of the system.
Does the PVE compensator need lockwiring?
On the PVE19 and PVE21, yes. The service instruction is to adjust the compensator and then drill through with a 0.1089 drill for the lockwire, so any adjustment means re-wiring afterwards.