Two flows in the housing, a third off the back
This double does not stop at two flows. A shaft-end section and a cover-end section sit on one shaft, each with its own outlet, and the same shaft runs out through the rear onto a splined coupling, so a third pump can be mounted behind it and driven from it — one drive, three pumped flows. The two built-in sections are read from their own tables and each keeps its own rating.
Three series are built: 3525VQT and 4525VQT on standard bearings, and 3625VQT, which is the 3525VQT on a heavy-duty bearing. The rear section is a 25VQ section on all three.
The code runs to 14 positions. Four of them describe the front of the pump and the two sections; the rest describe the rear — the mounting flange, the seal, the coupling, the shaft and the flange position.
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 | 3525VQT standard bearing · 3625VQT heavy-duty bearing · 4525VQT standard bearing |
| 3 | Rear mounting flange | A SAE “A” flange · B SAE “B” adapter flange · BP SAE “B” spacer flange for a PVE12/19/21 pump |
| 4 | Front mounting flange | S = SAE J-744 (127-2) |
| 5 | Shaft-end displacement | Code from the shaft-end table |
| 6 | Port connections | A = SAE 4-bolt flange · AM = metric 4-bolt flange |
| 7 | Cover-end displacement | Code from the 25VQ cover-end table |
| 8 | Shaft seal | S = single seal · omitted = double seal |
| 9 | Through-drive coupling | 2 = splined coupling for the pump behind |
| 10 | Shaft | 297 = splined |
| 11 | Port positions | Two letters, one per outlet, read from the cover end |
| 12 | Rear flange position | A = in line with outlet 2 · B = 90° from outlet 2, read from the cover end |
| 13 | Design | Designs 20 through 29 keep the same installation dimensions |
| 14 | Rotation | L counter-clockwise · R clockwise, read from the shaft end |
The model number printed with the code page reads 3525VQTAS-25A12-2297CC-20R. It is decoded position by position further down.
Series and the two mounting flanges: positions 2, 3 and 4
Position 2 gives the series, and with it the bearing size of the pump. Positions 3 and 4 describe the two mounting faces — the rear one, which takes the third pump, and the front one, which bolts to the machine:
| Position | Code | What it is |
|---|---|---|
| 3 — rear | A | SAE “A” flange, two-bolt |
| 3 — rear | B | SAE “B” adapter flange |
| 3 — rear | BP | SAE “B” spacer flange, for mounting a PVE12/19/21 piston pump |
| 4 — front | S | SAE J-744 front mounting flange, 127-2 |
The rear flange size also sets the torque the through-drive can carry, and it decides which pumps can be mounted behind — the “A” flange takes smaller pumps than the “B” one.
Two displacement codes: positions 5 and 7
Position 5 is the shaft-end section and position 7 the cover-end section. The two are coded on different families, and the cover-end section of every series in this group is a 25VQ section:
| Section | Series | Codes and displacement (cm³/r) |
|---|---|---|
| Shaft end (5) | 35 series on 3525VQT and 3625VQT · 45 series on 4525VQT | 25 = 81.6 · 30 = 97.7 · 35 = 112.8 · 38 = 121.6 · 42 = 138.7 · 50 = 162.3 · 60 = 193.4 |
| Cover end (7) | 25VQ | 12 = 40 · 14 = 45 · 17 = 55 · 21 = 68 |
Codes are SAE ratings in USgpm at 1200 r/min and 6.9 bar (100 psi), and the same code means a different displacement in the two tables, so the two sections are read separately.
Ports: position 6
One code covers the inlet and both outlets: A for SAE 4-bolt flanges, AM for metric. On a metric build the flange pads are stamped “M”, so the two are told apart on the pump itself. Port flange kits are supplied separately from the pump, and the kits for inch screws are a separate item again.
Shaft seal and coupling: positions 8 and 9
Position 8 is the one to read twice on this family. On a single pump the letter S means a double shaft seal; here it means a single seal, and the double seal is written by leaving the position out. The code page also notes that the position is omitted on the 25VQTA models.
Position 9 records the coupling: 2, the splined coupling that takes the tail shaft of the pump mounted behind. That rear pump’s shaft has to match the coupling, so it is chosen with the assembly rather than on its own.
Shaft: position 10
Position 10 gives the shaft: 297, a splined shaft — the one shaft listed for this family, since the shaft has to carry the drive through to the rear mounting. Its spline is dimensioned “C” size to SAE J744C in the current issue and to the earlier SAE J744 October 1983 issue as 32-4.
Outlet positions and the rear flange position: positions 11 and 12
Both of these are read from the cover end, but they measure different things. Position 11 places the two outlets: four positions for outlet 1, and for each of them four positions for outlet 2 measured relative to outlet 1 — sixteen pairs in all.
| Letter | Outlet 1 (first letter) | Outlet 2 (second letter), measured from outlet 1 |
|---|---|---|
| A | Opposite the inlet | 135° counter-clockwise |
| B | 90° counter-clockwise from the inlet | 45° counter-clockwise |
| C | Inline with the inlet | 45° clockwise |
| D | 90° clockwise from the inlet | 135° clockwise |
Position 12 then places the rear mounting flange relative to outlet 2: A puts it in line with outlet 2, B turns it 90° from outlet 2. It decides where the third pump sits 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. Position 14 gives the rotation seen from the shaft end: L for counter-clockwise, R for clockwise.
Two sections, two ratings
The two pumping sections are rated one by one, and on the 45 frame they do not match. The front section of the 4525VQT tops out at 172 bar, while its rear section — and both sections of the 35 frame pumps — run to 207 bar (3000 psi). Maximum speed steps down with the displacement code:
| Series | Front section: codes, speed and pressure | Rear section: codes, speed and pressure |
|---|---|---|
| 3525VQT and 3625VQT | 25 · 30 at 2500 r/min, 207 bar · 35 · 38 at 2400 r/min, 207 bar | 12 · 14 · 17 · 21 at 2500 r/min, 207 bar |
| 4525VQT | 42 · 50 · 60 at 2200 r/min, 172 bar | 12 · 14 · 17 · 21 at 2200 r/min, 207 bar |
The rating figures are quoted for SAE 10W oil at 82 °C (180 °F) with the inlet at 0 psig, and outlet pressure must always be higher than inlet pressure.
The through-drive torque check
The torque figures for these assemblies are given as a combined value — the through-drive double pump and the pump driven behind it together — so the check is made on the pair, not on the double pump alone:
| Series and rear flange | Combined input torque N·m (lb·in) | Through-drive torque N·m (lb·in) |
|---|---|---|
| 3525VQT / 3625VQT, flange A | 790 (7000) | 131 (1160) |
| 3525VQT / 3625VQT, flange B or BP | 790 (7000) | 316 (2800) |
| 4525VQT, flange A | 1017 (9000) | 131 (1160) |
| 4525VQT, flange B or BP | 1017 (9000) | 316 (2800) |
The rear flange size is the deciding factor on the second figure: an “A” flange carries 131 N·m whatever the series, while the “B” and “BP” flanges carry 316 N·m. Typical pumps mounted on these assemblies are the small piston pumps of the PVQ and PVE families on the “A” or “B” flange and V10, V20, 20V, 25V and V2020 vane pumps on the “B” flange, each with its own shaft code; the torque curves for the flange in use apply to whichever pump is chosen.
One model number, decoded
| Code | How it reads |
|---|---|
| 3525VQTAS-25A12-2297CC-20R | 3525VQT series on standard bearings; rear mounting flange A, SAE “A”; front flange S; shaft-end section 25, 81.6 cm³/r; port code A, 4-bolt flanges on the inlet and both outlets; cover-end section 12, 40 cm³/r; seal position left out, so a double shaft seal; coupling 2 for the pump behind; shaft 297, splined; outlets CC — outlet 1 inline with the inlet and outlet 2 at 45° clockwise from it; rear flange position left out, which the code page allows on the 25VQTA models; design 20; right-hand rotation |
Read the same way, a 4525VQT assembly differs in two places that matter: a shaft-end code from the 42, 50 or 60 group, and a front section rated 172 bar rather than 207.
VQT double: what to confirm before ordering
- Read the seal position the double-pump way. Here S is a single seal, and the double seal is written by leaving the position out.
- Take a pressure per section. On the 4525VQT the front section is rated 172 bar while the rear section runs to 207 bar.
- Keep position 11 and position 12 apart: one places the outlets relative to the inlet, the other places the rear flange relative to outlet 2.
- Read the two displacement codes on their own tables. Position 5 is coded on the 35 or 45 series and position 7 on the 25VQ section.
- Order the double together with the pump behind it: the coupling and the rear flange position are chosen for that pump, and the torque figures are the combined value for the pair.
- Include the port flanges. The flange kits ship separately from the pump, and the UNC-threaded ones are ordered on their own.
Ordering
Send the complete model number from the nameplate, or the combination you need — series, rear flange, both displacement codes and the outlet positions — and, where a pump is to be mounted behind, that pump’s model and shaft code as well. We confirm the assembly, the coupling, the flange position and the combined torque before the order is placed.
All pumps are supplied as new replacement units, inspected individually before dispatch.
Browse the VT and VQT through-drive series or the V and VQ double vane pumps.
