Overview and applications
What are V-belt pulleys?
A V-belt pulley (sheave) is a rotating disc with profiled grooves designed to guide and drive trapezoidal (V-belt) belts. The groove profiles conform to ISO 4183 / DIN 2211 standards and correspond to SPZ, SPA, SPB and SPC belt profiles. Pulleys are mounted on the shaft via a Taper Bush conical locking element — a standardised system enabling fast assembly and disassembly without heating or special tooling.
Nibora Ltd. offers a complete range of V-belt pulleys in cast iron G20 (UNI 5007) across 4 profiles (SPZ, SPA, SPB, SPC), with 1 to 10 grooves and pitch diameters from 50 to 1250 mm. Pulleys are available from stock or on request.
Applications — what are they used for?
V-belt drives with pulleys are one of the most widely used solutions for power transmission in industry — wherever power must be transferred from a motor to a driven machine with a change in speed (reduction or increase) and a defined centre distance.
| Industry / Application | Typical pulley use |
|---|---|
| Electric motors | Transmitting power from motor to fans, pumps, compressors |
| Agricultural machinery | Combines, seed drills, grain fans, conveyors |
| Woodworking | Circular saws, band saws, grinding machines, milling machines |
| Food processing | Mixers, conveyors, packaging machines |
| HVAC / Ventilation | Fans, air conditioning, extraction systems |
| Construction equipment | Concrete mixers, vibrators, hoists |
| Textile industry | Spinning and weaving machines |
| General engineering | Any drive requiring speed change via belt transmission |
Technical data and series
Technical specifications
Groove profiles — key parameters:
| Profile | Belt standard | dp min (mm) | dp max (mm) | Power (indicative) | Grooves |
|---|---|---|---|---|---|
| SPZ | SPZ / Z / XPZ | 50 | 800 | up to ~4 kW per groove | 1 – 8 |
| SPA | SPA / A / XPA | 63 | 1000 | up to ~8 kW per groove | 1 – 6 |
| SPB | SPB / B / XPB | 100 | 1250 | up to ~15 kW per groove | 1 – 10 |
| SPC | SPC / C / XPC | 200 | 1250 | up to ~30 kW per groove | 3 – 10 |
Note: Power per groove is indicative and depends on belt speed, arc of contact and operating conditions.
Material and construction
| Parameter | Value |
|---|---|
| Material | Grey cast iron G20 / Ghisa G20 |
| Material standard | UNI 5007 |
| Groove profile standard | ISO 4183 / DIN 2211 |
| Mounting system | Taper Bush (conical locking element) |
| Finish | Bare cast iron — standard; painted on request |
| Balancing | Statically balanced for larger dp |
Taper Bush sizes and maximum bore
Pulleys are mounted on the shaft via standard Taper Bush conical bushings. When ordering, specify the Taper Bush size and the shaft diameter.
| Taper Bush | Min bore (mm) | Max bore (mm) | Typical for pulley dp (mm) |
|---|---|---|---|
| 1008 | 10 | 25 | SPZ 50–56, SPA 63–67 |
| 1108 | 12 | 28 | SPZ 60–75, SPA 67–85 |
| 1210 | 12 | 32 | SPZ 80–100, SPA 80–95 |
| 1610 | 14 | 42 | SPZ 106–200, SPA 100–170, SPB 100–180 |
| 2012 | 16 | 50 | SPZ 200–315, SPA 132–300, SPB 125–212 |
| 2517 | 18 | 65 | SPZ 250–500, SPA 200–500, SPB 150–335, SPC 200–280 |
| 3020 | 24 | 75 | SPZ 400–630, SPA 300–630, SPB 250–450, SPC 212–400 |
| 3535 | 35 | 90 | SPZ 800, SPA 800, SPB 400–1000, SPC 265–450 |
| 4040 | 40 | 100 | SPB 800–1250, SPC 530–800 |
| 4545 | 45 | 110 | SPC 710–1250, SPB 1000–1250 |
| 5050 | 50 | 125 | SPC 800–1250 (heavy duty) |
SPZ series range — grooves and diameters
| Grooves | dp min (mm) | dp max (mm) | F (pulley width, mm) | Taper Bush range |
|---|---|---|---|---|
| 1 | 50 | 450 | 16–16 | 1008 – 2517 |
| 2 | 50 | 500 | 28–28 | 1008 – 2517 |
| 3 | 63 | 800 | 40–40 | 1108 – 3020 |
| 4 | 71 | 800 | 52–52 | 1108 – 3030 |
| 5 | 85 | 800 | 64–64 | 1610 – 3535 |
| 6 | 90 | 800 | 76–76 | 1610 – 3535 |
| 8 | 140 | 500 | 100–100 | 2517 – 3535 |
SPA series range — grooves and diameters
| Grooves | dp min (mm) | dp max (mm) | F (width, mm) | Taper Bush range |
|---|---|---|---|---|
| 1 | 63 | 630 | 20 | 1008 – 2517 |
| 2 | 63 | 630 | 35 | 1008 – 3020 |
| 3 | 71 | 1000 | 50 | 1108 – 3535 |
| 4 | 90 | 1000 | 65 | 1615 – 4040 |
| 5 | 100 | 1000 | 80 | 1615 – 4545 |
| 6 | 100 | 1000 | 95 | 1610 – 4545 |
SPB series range — grooves and diameters
| Grooves | dp min (mm) | dp max (mm) | F (width, mm) | Taper Bush range |
|---|---|---|---|---|
| 1 | 100 | 315 | 25 | 1610 – 2012 |
| 2 | 100 | 630 | 44 | 1610 – 3030 |
| 3 | 100 | 1250 | 63 | 1610 – 4040 |
| 4 | 118 | 1250 | 82 | 1610 – 4545 |
| 5 | 125 | 1250 | 101 | 2012 – 4545 |
| 6 | 140 | 1250 | 120 | 2517 – 4545 |
| 8 | 140 | 1250 | 158 | 2517 – 5050 |
| 10 | 224 | 1250 | 196 | 3535 – 5050 |
SPC series range — grooves and diameters
| Grooves | dp min (mm) | dp max (mm) | F (width, mm) | Taper Bush range |
|---|---|---|---|---|
| 3 | 200 | 1250 | 85 | 2517 – 5050 |
| 4 | 200 | 1250 | 111 | 3020 – 5050 |
| 5 | 200 | 1250 | 136 | 3535 – 5050 |
| 6 | 200 | 1250 | 162 | 3535 – 5050 |
| 8 | 200 | 1250 | 213 | 3535 – 5050 |
| 10 | 250 | 1250 | 264 | 4040 – 5050 |
V-belt pulleys Taper Bush
Download PDF ↓FAQ — Frequently Asked Questions
How do I calculate the speed ratio of a V-belt drive?
Speed ratio i = dp2 / dp1, where dp1 is the pitch diameter of the driving pulley (motor side) and dp2 is the driven pulley. Output speed: n2 = n1 / i. Example: motor at 1450 rpm, dp1 = 100 mm, dp2 = 200 mm → i = 2, n2 = 725 rpm. For speed reduction: dp2 > dp1. For speed increase: dp2 < dp1.
What is the difference between SPZ, SPA, SPB and SPC profiles?
The profiles differ in groove size and power capacity: SPZ (smallest) — light drives up to ~4 kW/groove; SPA — medium drives up to ~8 kW/groove; SPB — heavy drives up to ~15 kW/groove; SPC (largest) — very heavy drives up to ~30 kW/groove. Each profile matches a specific belt type (SPZ belt in SPZ pulley, etc.).
What is a Taper Bush and how is the pulley mounted?
A Taper Bush is a tapered steel element that locks between the shaft and the pulley hub via bolts. It allows assembly and disassembly without heating, press-fit tools or shaft damage. When ordering, specify: groove profile and dp, number of grooves, Taper Bush size, shaft diameter.
What is the difference between dp (pitch diameter) and de (external diameter)?
dp (pitch diameter) is the diameter along which the belt centreline runs — used for all speed calculations. de is the actual outside diameter of the pulley. Differences: SPZ: de = dp + 4 mm; SPA: de = dp + 5.5 mm; SPB: de = dp + 7 mm; SPC: de = dp + 9.6 mm.
How do I select the correct number of grooves?
The number of grooves is determined by the required power transmission: grooves needed = P_design / P_per_groove. P_per_groove depends on the profile, dp and belt speed. Larger dp gives higher power per groove. More grooves means a more compact, higher-power drive for the same overall size.
How do I reduce speed using V-belt pulleys?
Fit a smaller pulley on the motor (dp1) and a larger one on the driven machine (dp2). Example: motor 1450 rpm, dp1 = 80 mm (SPZ), dp2 = 320 mm → n2 = 1450 × 80 / 320 = 362 rpm. A typical single V-belt stage achieves ratios up to 1:6–1:8.
Can non-standard bore sizes be ordered?
Yes — pulleys with non-standard bores (bored to size), additional machining or special profiles are available on request. Contact our technical department: nibora@nibora.com, +359 64 681 058.