One motor, two pumps
A VT is the V series single pump prepared for a rear drive: the back cover takes an adapter plate and a splined coupling, so a second pump can be bolted behind and driven from the tail of the VT shaft instead of from a motor of its own. The pumping end is untouched — same cartridge, same ports, same 172 bar rating as the V series — so everything that separates a V from a VT sits in the rear positions of the string, and those are the ones this article works through.
Three frame sizes are built: 25VT, 35VT and 45VT, covering 33 to 193 cm³/r. There is no 20VT.
The code runs to 13 positions, three more than the V single pump, because the rear of the pump has to be described as well as the front.
The 13 positions at a glance
| # | Position | What it sets |
|---|---|---|
| 1 | Seals | F3 for phosphate-ester and fire-resistant fluids; omitted for mineral oil |
| 2 | Series | 25VT · 35VT · 45VT |
| 3 | Rear pump mounting | A SAE “A” · B SAE “B” · C SAE “C” (35VT and 45VT only) · BP SAE “B” for a PVE12/19/21 piston pump |
| 4 | Pilot | S standard pilot per ISO 3019/1 (SAE J744) · M metric per ISO 3019/2 (100A2HW) |
| 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 on the 4-bolt flange |
| 8 | Thru-drive coupling | 2 = splined coupling supplied with the pump |
| 9 | Shaft | 202 SAE straight key · 292N ISO metric key · 297 SAE spline · 203 SAE heavy-duty straight key |
| 10 | Outlet position | A · B · C · D, read from the cover end |
| 11 | Adapter orientation | A or B, read from the cover end |
| 12 | Design | The design number of the build |
| 13 | Rotation | L counter-clockwise · R clockwise, read from the shaft end |
A nameplate code reads as 25VTAS14A 2297AA 22R: series 25VT, rear mounting A, pilot S, displacement 14, port A, inch threads, coupling 2, shaft 297, outlet position A, adapter orientation A, design 22, right-hand rotation.
Series and rear pump mounting: positions 2 and 3
Position 2 fixes the frame size and with it the displacement range. Position 3 fixes the SAE size of the two-bolt mounting at the rear, which is what decides which pumps can be bolted on behind:
| Code | Rear mounting | Available on |
|---|---|---|
| A | SAE “A” two-bolt | all three frames |
| B | SAE “B” two-bolt | all three frames |
| C | SAE “C” two-bolt | 35VT and 45VT only |
| BP | SAE “B” with a spacer | all three frames, for mounting a PVE12/19/21 piston pump |
The mounting size also sets the torque the thru-drive can carry, and the two later positions — coupling and adapter orientation — are read against the same choice.
Pilot and displacement: positions 4 and 5
Position 4 names the pilot: S for the standard pilot to ISO 3019/1 (SAE J744) and M for the metric pilot to ISO 3019/2. Both are written; there is no omitted-pilot build on this series.
Position 5 is the displacement of the pumping section, coded on the frame size and rated at 1200 r/min and 6.9 bar (100 psi):
| Frame | Codes and displacement (cm³/r) |
|---|---|
| 25VT | 10 = 33 · 12 = 40 · 14 = 45 · 17 = 55 · 21 = 67 |
| 35VT | 25 = 81 · 30 = 97 · 35 = 112 · 38 = 121 |
| 45VT | 42 = 138 · 45 = 147 · 50 = 162 · 60 = 193 |
Ports: positions 6 and 7
Position 6 carries a single code, A, an SAE 4-bolt flange on the inlet and on the outlet. Position 7 decides the threads that fasten those flanges: omitted for inch threads, M for metric. The flange itself stays the same 4-bolt pattern either way.
Coupling and tail shaft: position 8
Position 8 records the coupling: 2 means a splined coupling is supplied with the pump. The adapter size chosen at position 3 then fixes the shaft the rear pump must have — its tail shaft has to match the coupling spline:
| Adapter | Tail shaft required on the rear pump |
|---|---|
| VTA (SAE “A”) | 30° involute spline, 9 teeth, 16/32 D.P. |
| VTB (SAE “B”) | 30° involute spline, 13 teeth, 16/32 D.P. |
| VTC (SAE “C”) | 30° involute spline, 14 teeth, 12/24 D.P. |
The tail shaft is the rear pump’s own shaft, so the match is made when the pair is chosen rather than when the VT is ordered on its own.
Shaft: position 9
Unlike the V single pump, where the shaft list follows the pilot, here it follows the frame size:
| Frame | SAE straight key | ISO metric key | SAE spline | SAE heavy-duty key |
|---|---|---|---|---|
| 25VT | 202 | 292N | 297 | 203 |
| 35VT and 45VT | not available | 292N | 297 | 203 |
The 202 straight key shaft is offered on the 25VT only, so a 35VT or 45VT cannot be ordered with it. The shaft number also matters on the torque side, because each one carries its own limit.
Two letters, two positions: 10 and 11
Positions 10 and 11 sit next to each other and both take a single letter, so a code shows a pair of letters such as AA or CA. They are two different settings, read from the cover end:
| Letter | Position 10 — outlet position | Position 11 — adapter orientation |
|---|---|---|
| A | Opposite the inlet | SAE “A” adapter: rotated 45° clockwise from the pump mounting flange · “B”, “BP” or “C” adapter: in line with the pump mounting flange |
| B | 90° counter-clockwise from the inlet | SAE “A” adapter: rotated 45° counter-clockwise · “B”, “BP” or “C” adapter: rotated 90° |
| C | Inline with the inlet | — |
| D | 90° clockwise from the inlet | — |
The adapter position matters because it turns the rear mounting relative to the pump flange, and the rear pump has to sit where the machine can reach it.
Design and rotation: positions 12 and 13
Position 12 carries the design number of the build, and position 13 the direction of rotation seen from the shaft end: L for counter-clockwise and R for clockwise. Both letters are written on this series, so the rotation is never left to be assumed.
Ratings and the thru-drive torque check
The pumping section carries the V series rating: 172 bar (2500 psi) maximum continuous pressure and 1800 r/min maximum speed on anti-wear hydraulic oil, with a minimum of 600 r/min. The medium pulls both figures down: an oil-in-water emulsion is limited to 69 bar, a water-glycol fluid to 159 bar, and the speed to 1200 r/min on synthetic fluids and emulsions and 1500 r/min on water-glycol. Transient pressure may run 10% above the continuous rating for no more than 0.5 seconds.
What the thru-drive adds is a second limit. When the VT 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 connection:
| Frame and shaft | Shaft limit N·m (lb·in) | Connection A | Connection B | Connection C |
|---|---|---|---|---|
| 25VT, shaft 202 | 250 (2200) | 131 (1160) | 250 (2200) | — |
| 25VT, shafts 203 / 297 / 292N | 316–400 (2800–3560) | 131 (1160) | 316 (2800) | 400 (3560) at the 400 N·m shaft limit |
| 35VT, shaft 203 / 297 | 600–790 (5300–7000) | 131 (1160) | 316 (2800) | 437 (3870) |
| 35VT, shaft 292N | 904 (8000) | 131 (1160) | 384 (3400) | 702 (6210) |
| 45VT, shaft 203 / 297 | 810–1020 (7200–9000) | 131 (1160) | 384 (3400) | 702 (6210) |
Two details are easy to miss. The SAE “A” connection carries 131 N·m (1160 lb·in) on every frame size, so the smallest rear mounting is the tightest limit. And the 25VT with the 292N shaft is listed twice — at a 316 N·m shaft limit the “C” connection is not available, and only the 400 N·m row reaches it. The rear pump’s own speed limits apply as well, so the pair is checked as a pair.
Five stock codes, decoded
| Code | How it reads |
|---|---|
| 25VTAS14A 2297AA 22R | 25VT frame; rear mounting A, SAE “A”; pilot S; 45 cm³/r; port A; inch threads; coupling supplied; shaft 297, SAE spline; outlet A, opposite the inlet; adapter A; design 22, right-hand rotation |
| 25VTAS17A 2202CC 22L | 55 cm³/r; shaft 202, the straight key shaft offered on the 25VT only; outlet C, inline with the inlet; adapter C; design 22, left-hand rotation |
| 35VTAS25A 2297AA22R | 35VT frame; rear mounting A; 81 cm³/r; port A; shaft 297; outlet A and adapter A; design 22, right-hand rotation |
| 45VTBS60A 2203CA 22R | 45VT frame; rear mounting B, SAE “B”; 193 cm³/r, the largest in the series; port A; shaft 203, heavy-duty straight key; outlet C, inline with the inlet; adapter A; design 22, right-hand rotation |
| 45VTBPS42A 2203AA22R | 45VT frame; BP rear mounting, the SAE “B” variant with a spacer for a PVE12/19/21 piston pump; 138 cm³/r; shaft 203; outlet A and adapter A; design 22, right-hand rotation |
VT: what to confirm before ordering
- Read the two letters as two settings. Position 10 places the outlet, position 11 the adapter.
- Match the shaft code to the frame. The straight key 202 shaft is built for the 25VT; the larger frames use the metric key, spline or heavy-duty key shafts.
- Write the pilot in. This series has no omitted-pilot build; either S or M appears in the code.
- Check the through-drive torque against both limits. The SAE “A” connection is limited to 131 N·m on every frame, and the 25VT with the 292N shaft has two different shaft limits.
- Check the front and the rear pump together. The combined torque of the VT and the rear pump goes against the shaft limit, and the rear pump’s requirement against the connection limit.
- Order the two pumps as a pair. The coupling and the adapter-plate position are chosen for the pump that goes behind.
Ordering
Send the complete model code from the nameplate, or the combination you need — frame, rear mounting, 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 VT through-drive vane pumps or the wider VT and VQT through-drive series.
