Front half VQ, rear half its own positions
A VQT drives a second pump from the tail shaft, and it does so from a VQ front end: the pump is a VQ single unit with a two-bolt through-drive adapter and a splined coupling at the rear. The front half keeps the VQ numbers — Intravane cartridge, 210 bar on the 25 and 35 frames — while the rear half is described in positions of its own. The two letters at the end of the string are the ones most often misread.
Five series are built. 25VQT, 35VQT and 45VQT run standard bearings; 26VQT and 36VQT are the same pumps on heavy-duty bearings.
The code runs to 14 positions — four more than the VQ single pump — because the adapter, the front flange, the shaft seal and the coupling are all named separately on a thru-drive build.
The 14 positions at a glance
| # | Position | What it sets |
|---|---|---|
| 1 | Seals | F3 for phosphate-ester and fire-resistant fluids; omitted for mineral oil |
| 2 | Series | 25VQT · 35VQT · 45VQT standard bearing · 26VQT · 36VQT heavy-duty bearing |
| 3 | Thru-drive adapter | A SAE “A” · B SAE “B” · BP SAE “B” with a spacer for a PVE12/19/21 piston pump · C SAE “C” (not on 25VQT) |
| 4 | Front mounting flange | S, with the flange size fixed by the series |
| 5 | Displacement | Code from the displacement table |
| 6 | Port connections | A = SAE 4-bolt flange |
| 7 | Port thread modifier | Omitted = inch threads · M = metric threads |
| 8 | Shaft seal | S = double shaft seal · omitted = single seal |
| 9 | Coupling for the rear pump | 2 = SAE splined coupling supplied with the pump |
| 10 | Shaft | 202 straight key · 203 heavy-duty straight key · 297 splined |
| 11 | Outlet position | A · B · C · D, read from the cover end |
| 12 | Adapter orientation | A or B, read from the cover end |
| 13 | Design | Designs -20 to -29 keep the same installation dimensions |
| 14 | Rotation | L counter-clockwise · R clockwise, read from the shaft end |
A nameplate code reads as 25VQTBS17A 2297AA 20R: series 25VQT, adapter B, front flange S, displacement 17, port A, inch threads, single seal, coupling 2, shaft 297, outlet position A, adapter orientation A, design 20, right-hand rotation.
Series and adapter: positions 2 and 3
Position 2 gives the series, and with it the bearing size and the displacement range. Position 3 gives the SAE size of the thru-drive connection, which is what decides both the pump that can be mounted behind and the torque that connection will carry:
| Code | Thru-drive adapter, two-bolt | Available on |
|---|---|---|
| A | SAE “A” size | all series |
| B | SAE “B” size | all series |
| BP | SAE “B” size with a spacer, for a PVE12/19/21 piston pump | all series |
| C | SAE “C” size | not available on 25VQT |
The heavy-duty bearing series carry the same adapter choices as the standard ones, so 26VQT and 36VQT follow 25VQT and 35VQT here.
Front flange and displacement: positions 4 and 5
Position 4 is a fixed letter on this series: S, the SAE J744 front mounting flange. What changes is the flange size, which is settled by the series and cannot be ordered the other way:
The flange is SAE “B” (101-2) on the 25VQT and 26VQT, and SAE “C” (127-2) on the 35VQT, 36VQT and 45VQT.
Position 5 is the displacement of the shaft-end section, coded on the series and rated at 1200 r/min:
| Series | Codes and displacement (cm³/r) |
|---|---|
| 25VQT and 26VQT | 12 = 40.2 · 14 = 45.4 · 17 = 55.2 · 21 = 67.5 |
| 35VQT and 36VQT | 25 = 81.6 · 30 = 97.7 · 35 = 112.8 · 38 = 121.6 |
| 45VQT | 42 = 138.7 · 50 = 162.3 · 60 = 193.4 |
Ports: positions 6 and 7
Position 6 carries one code, A: an SAE 4-bolt flange on the inlet and on the outlet. Position 7 sets the thread that fastens the flanges — omitted for inch, M for metric — and a metric build is stamped M on the port pad so the two are told apart on the pump itself.
Shaft seal and coupling: positions 8 and 9
Position 8 records the shaft seal: S for a double shaft seal, and nothing for a single seal. It is a position of its own on this series, which is what allows a single-seal pump to be written without any seal letter at all.
Position 9 records the coupling: 2 means the SAE splined coupling for the rear pump is supplied with the pump. The tail shaft of that rear pump has to match the coupling spline, so the rear pump’s shaft is settled when the pair is chosen.
Shaft: position 10
Three shafts are used across the series:
| Code | Shaft | Notes |
|---|---|---|
| 202 | Straight keyed | Listed with the series service data |
| 203 | Heavy-duty straight keyed | Listed on the model-code page |
| 297 | Splined | Listed on the model-code page |
The torque ratings that follow are given for the 203 and 297 shafts. A build on the straight keyed 202 is checked against the installation.
Two letters, two positions: 11 and 12
Positions 11 and 12 sit next to each other and both take a single letter, so a code shows a pair such as AA or CA. They are two different settings, both read from the cover end:
| Letter | Position 11 — outlet position | Position 12 — adapter orientation |
|---|---|---|
| A | Opposite the inlet | “A” adapter: rotated 45° clockwise from the pump mounting flange · “B” adapter: in line with the pump mounting flange |
| B | 90° counter-clockwise from the inlet | “A” adapter: rotated 45° counter-clockwise · “B” adapter: rotated 90° |
| C | Inline with the inlet | — |
| D | 90° clockwise from the inlet | — |
The adapter letter turns the rear mounting relative to the pump flange, so it decides where the second pump ends up on the machine.
Design and rotation: positions 13 and 14
Position 13 carries the design number; designs -20 through -29 share the same installation dimensions, so a later design does not move the mounting. Position 14 gives the rotation seen from the shaft end: L for counter-clockwise and R for clockwise.
Ratings and the thru-drive torque check
The VQ section sets the pressure and speed of the pump, and both figures step down with the frame size and the displacement code:
| Series | Displacement codes | Maximum speed (r/min) | Maximum pressure |
|---|---|---|---|
| 25VQT | 12 · 14 | 2700 | 210 bar (3000 psi) |
| 25VQT | 17 · 21 | 2500 | 210 bar (3000 psi) |
| 35VQT | 25 · 30 | 2500 | 210 bar (3000 psi) |
| 35VQT | 35 · 38 | 2400 | 210 bar (3000 psi) |
| 45VQT | 42 · 50 · 60 | 2200 | 175 bar (2500 psi) |
The 45VQT runs at 175 bar where the smaller frames run at 210. Outlet pressure must always be higher than inlet pressure.
The thru-drive adds a second limit. When the VQT and the pump behind it are both on load, two checks apply: the combined torque of the two pumps must stay within the shaft limit, and the torque the rear pump needs must stay within the thru-drive limit of the adapter:
| Series | Shaft | Shaft limit N·m (lb·in) | Adapter A | Adapter B | Adapter C |
|---|---|---|---|---|---|
| 25VQT | 203 | 402 (3560) | 131 (1160) | 316 (2800) | — |
| 25VQT | 297 | 344 (3040) | 131 (1160) | 316 (2800) | — |
| 35VQT | 203 | 659 (5830) | 131 (1160) | 348 (3080) | 437 (3870) |
| 35VQT | 297 | 791 (7000) | 131 (1160) | 348 (3080) | 437 (3870) |
| 45VQT | 203 | 982 (8690) | 131 (1160) | 384 (3400) | 702 (6210) |
| 45VQT | 297 | 1017 (9000) | 131 (1160) | 384 (3400) | 702 (6210) |
Two points are worth keeping in view. The SAE “A” adapter carries 131 N·m (1160 lb·in) whatever the frame size, so the smallest connection is the tightest limit; and the 25VQT has no “C” adapter at all, which is also why the column is empty for that series in the table above.
Five stock codes, decoded
| Code | How it reads |
|---|---|
| 25VQTBS17A 2297AA 20R | 25VQT frame; adapter B, SAE “B”; front flange S; 55.2 cm³/r at 210 bar; port A; inch threads; single shaft seal; coupling supplied; shaft 297, splined; outlet A, opposite the inlet; adapter orientation A; design 20, right-hand rotation |
| 35VQTBS21A 2203AA20R | 35VQT frame; adapter B; front flange SAE “C”; 67.5 cm³/r at 210 bar; shaft 203, heavy-duty straight key; outlet A and adapter orientation A; design 20, right-hand rotation |
| 35VQTBS35A 2297CA 20R | 112.8 cm³/r at 2400 r/min; shaft 297, splined; outlet C, inline with the inlet; adapter orientation A; design 20, right-hand rotation |
| 45VQTCS42A 2297AA20R | 45VQT frame; adapter C, SAE “C” — the size the 25VQT cannot take; 138.7 cm³/r at 175 bar; shaft 297; outlet A and adapter orientation A; design 20, right-hand rotation |
| 45VQTBS50AS-2297AA-21R | 162.3 cm³/r at 175 bar; port A with M omitted, inch threads; S, double shaft seal; shaft 297; outlet A and adapter orientation A; design 21, right-hand rotation |
VQT: what to confirm before ordering
- Read the two letters as two settings. Position 11 places the outlet, position 12 the adapter.
- Match the adapter code to the frame. The SAE “C” connection starts at the 35VQT.
- Note that position 4 is written S; the flange size follows the series.
- Take the pressure from the frame: the 45 frame is rated 175 bar, against 210 bar on the smaller frames.
- Check the through-drive torque against both limits: the “A” adapter is limited to 131 N·m on every series, and the 25VQT stops at the “B” adapter.
- Check the front and the rear pump together. The combined torque goes against the shaft limit, and the rear pump’s requirement against the adapter limit.
Ordering
Send the complete model code from the nameplate, or the combination you need — series, adapter, shaft and outlet position — and, where a second pump is to be mounted behind it, the code of that pump as well. We confirm the pair, the coupling and the adapter orientation before the order is placed.
All pumps are supplied as new replacement units, inspected individually before dispatch.
Browse the VQT through-drive vane pumps or the wider VT and VQT through-drive series.
