What a VQ single pump is
A VQ single pump is the high-pressure version of the balanced vane pump: one cartridge on one shaft, fixed displacement, hydraulic balance that cancels the radial load. It is rated above the V line — 210 bar and up to 2700 r/min, against 172–207 bar at 1800 r/min — and covers 20VQ, 25VQ, 26VQ, 30VQ, 31VQ, 35VQ, 36VQ and 45VQ from 18 to 193 cm³/r; 26VQ and 36VQ are heavy-duty bearing versions of the same frames and 30VQ and 31VQ the widened 25V frame. Like the V line it is cartridge type and, unlike a V single pump, has case ports: a tank port and a primary outlet port.
The 10 code positions
25VQ to 45VQ are ordered through 10 positions. A position is omitted when the standard value applies, and an omitted position does not shift those that follow.
| # | Position | Values |
|---|---|---|
| 1 | Seals | F3 for phosphate-ester and fire-resistant fluids; omitted for mineral oil |
| 2 | Series | 25VQ · 26VQ · 30VQ · 31VQ · 35VQ · 36VQ · 45VQ |
| 3 | Pilot | Omitted = standard; S = SAE per ISO 3019/1, written 25VQS… |
| 4 | Displacement | Code from the table below |
| 5 | Port | A = SAE 4-bolt flange · AM = the same, metric fasteners · B = straight thread · C = flange inlet, thread outlet · D = thread inlet, flange outlet — B, C, D on the 25VQ only |
| 6 | Mounting and shaft seal | Omitted = flange with a single seal · F = foot with a single seal · S = flange with a double seal |
| 7 | Shaft | Shaft table below |
| 8 | Outlet position | A · B · C · D |
| 9 | Design number | 20 |
| 10 | Rotation | L or R; omitted means right-hand |
The string is written in groups: series with pilot and displacement, then port, then after the hyphen shaft, outlet position, design and rotation. Position 6 is the mounting and shaft-seal assembly and position 3 the mounting pilot, so they are independent.
Position 4: displacement codes
| Code | 25VQ · 26VQ | 30VQ · 31VQ | 35VQ · 36VQ | 45VQ |
|---|---|---|---|---|
| Displacement (cm³/r) | 12 = 40.2 14 = 45.4 17 = 55.2 19 = 61.3 21 = 67.5 |
24 = not published 28 = not published |
21 = not published 25 = 81.6 30 = 97.7 35 = 112.8 38 = 121.6 |
42 = 138.7 47 = 157.9 50 = 162.3 57 = 190.2 60 = 193.4 |
The code is the SAE rated capacity in US gpm at 1200 r/min and 7 bar, not a geometric displacement — so the three codes marked not published carry no cm³/r figure, and we do not back-calculate one. Codes 19, 47 and 57 come from the same-family high-pressure sample. A code also differs across series: 21 is 67.5 cm³/r on the 25VQ, while the 35VQ has its own 21.
Pressure and speed: two derating rules
| Series | Codes | Maximum speed | Maximum pressure |
|---|---|---|---|
| 20VQ | 5 · 8 · 11 | 2700 r/min | 210 bar |
| 25VQ | 12 · 14 · 17 · 21 | 2700 · 2500 r/min | 210 bar |
| 35VQ | 25 · 30 · 35 · 38 | 2500 · 2400 r/min | 210 bar |
| 45VQ | 42 · 50 · 60 | 2200 r/min | 175 bar |
Figures are at SAE 10W oil, 82 °C and a 0 psig inlet. Two rules follow. On the 20VQ the larger codes cut the pressure limit — 12 is 160 bar, 14 is 140 bar, while 5, 8 and 11 reach 210 bar — and every 45VQ is limited to 175 bar. On 25VQ and 35VQ the pressure holds at 210 bar and only the speed falls with displacement.
Positions 5, 6 and 7: ports, mounting and shaft
| Pilot and seal | Shaft codes |
|---|---|
| Standard pilot, single seal | 1 keyed · 3 keyed with nut · 6 keyed · 11 splined · 86 heavy-duty keyed · 4 splined on the 35VQ and 45VQ |
| Standard pilot, double seal | 123 — not on the 45VQ · 130 — 45VQ only |
| S — SAE pilot | 203 heavy-duty keyed · 297 splined |
A double shaft seal is not a separate option — it is carried by the mounting code S in position 6, which also changes which shafts are available. The SAE-pilot shafts belong to the S branch of position 3, so position 3 is read first.
Position 5 offers five combinations: A is the SAE 4-bolt flange on both ports and AM the same flange with metric fasteners, both listed across the family, while B uses straight threads on both ports and C and D mix a flange with a straight thread — those three are listed on the 25VQ only. Flange faces scale with the frame (inlet/outlet ø38.1/19.0 mm on the 20VQ through ø76.2/38.1 mm on the 45VQ), with metric threads available on every frame. Standard mounting is the flange, F specifying a foot bracket, and the same position carries the seal. The VQ pump also has case ports, a tank port .750-16UNF-2B and a primary outlet port .875-14 UNF-2B, connected independently of the main ports.
Outlet position (position 8) is read from the cover end: A opposite the inlet, B 90° counter-clockwise, C in line with the inlet, D 90° clockwise — C lies on the same line as the inlet, B and D are mirror images. Rotation (position 10) is read from the shaft end: L left-hand, R right-hand, omitted meaning right-hand.
Four stock codes, decoded
| Code | How it reads |
|---|---|
| 25VQ12A 11C20 | 25VQ · 12 = 40.2 cm³/r, 210 bar at 2700 r/min · port C · shaft 11 splined · outlet C · design 20, right-hand |
| 26VQ21A 1C20 LH | 26VQ, heavy-duty bearing frame · 21 = 67.5 cm³/r · shaft 1 keyed · outlet C, left-hand |
| 30VQ28A 1B20 | 30VQ, widened 25V frame · 28, a US gpm rating with no cm³/r figure · port B straight thread · shaft 1 keyed · outlet B |
| 45VQ50A 11D20 | 45VQ · 50 = 162.3 cm³/r, 175 bar at 2200 r/min · shaft 11 splined · outlet D, 90° clockwise |
Each code links to its product page. On a worn nameplate the design number separates the codes before any other position is read: the industrial VQ single pump carries 20 and the V single pump 22. The 20VQ is a separate mobile design on its own 12-position code, design number 30, with extra integral valve, controlled flow and relief setting positions — read it against its own table.
Common ordering errors
- Treating VQ as a higher-rated V. Different codes and limits: a V code read against the VQ table returns the wrong displacement.
- Taking pressure from the size rather than the code. 20VQ codes 12 and 14 fall to 160 and 140 bar; every 45VQ is 175 bar.
- Confusing the two meanings of S, or reading rotation from the cover end. In position 3 S is the SAE pilot, in position 6 flange mounting with a double seal; rotation is judged at the shaft end.
Ordering
All units are new aftermarket replacements, quality checked before shipping. Send the model code from the nameplate, or the code required, and we confirm series, displacement, shaft, port and mounting before the order is placed; if the nameplate is unreadable, photographs and the machine model are enough.
Browse the VQ single vane pumps, the V and VQ single pumps, the V · VQ · 50V series hub, or the V and VQ cartridge kits.
