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When a single-groove pulley can't transmit enough torque or you need redundancy in your belt drive, a double groove V belt pulley is the answer. Mechanical engineers, machine builders, and workshop owners who run motors, compressors, fans, or conveyor systems often need a reliable dual-belt aluminum pulley that fits a range of shaft sizes without custom machining.
These aluminum double groove V belt pulleys are machined from aluminum alloy and feature two parallel V-grooves sized for O-section or Z-section V belts. Outer diameters are available in 40mm (1.57 in), 50mm (1.97 in), and 60mm (2.36 in), with bore diameters ranging from 8mm to 25mm (0.31 in to 0.98 in) to suit common motor and gearbox shaft sizes.
Typical applications include dual-belt motor-to-gearbox drives on industrial machinery, twin-belt conveyor head pulleys where load sharing is critical, and workshop equipment such as lathes, drill presses, and band saws that use O or Z section V belts for speed reduction and torque transmission.
Two parallel V-grooves allow you to run two O/Z section belts simultaneously, doubling torque capacity and providing a safety margin if one belt stretches or fails during operation.
Aluminum construction keeps rotating mass low, reducing motor load at startup and minimizing bearing wear — a practical advantage over cast iron alternatives in light-to-medium duty applications.
Choose from 40mm (1.57 in), 50mm (1.97 in), or 60mm (2.36 in) outer diameters to achieve the speed ratio your drive system requires without modifying your frame or motor mount.
Bore sizes from 8mm to 25mm cover the most common motor shaft diameters used in single-phase and three-phase induction motors, making this pulley a versatile fit across many machine types.
Each pulley is fitted with a set screw for secure shaft locking, allowing installation without a press or special tooling while maintaining concentricity under load.
Dimensionally matched to standard O/Z section V belt groove profiles, these pulleys drop into existing drive arrangements as a direct replacement or upgrade from worn single-groove units.
| Groove Type | Double groove (2 grooves) |
|---|---|
| Belt Section | O-section / Z-section V belt |
| Outer Diameter (OD) | 40mm (1.57 in) / 50mm (1.97 in) / 60mm (2.36 in) |
| Bore Diameter | 8 / 10 / 12 / 14 / 15 / 16 / 17 / 18 / 19 / 20 / 22 / 24 / 25mm (see variant options) |
| Material | Aluminum alloy |
| Shaft Retention | Set screw |
| Hub Length | See variant options |
| Quantity per Order | 1 piece |
The outer diameter (OD) determines your speed ratio when paired with a pulley on the driven shaft. A smaller driver pulley and larger driven pulley reduces speed and increases torque. Calculate your required ratio by dividing the driven pulley OD by the driver pulley OD. For example, a 40mm driver paired with a 60mm driven pulley gives a 1.5:1 reduction. Choose the OD that achieves your target RPM at the driven shaft.
Measure your motor shaft diameter with calipers before ordering. Common single-phase motor shafts are 14mm, 16mm, or 19mm; three-phase motors often use 19mm, 22mm, or 24mm shafts. The bore must match the shaft exactly — a loose fit causes vibration and accelerated wear even with the set screw tightened. If your shaft is between sizes, select the bore that matches the shaft, not the next size up.
These pulleys are grooved for O-section (also called Z-section in some standards) V belts. O/Z section belts have a top width of approximately 10mm and a height of approximately 6mm. Do not use A-section, B-section, or other profiles — the groove angle and depth are specific to O/Z belts and mismatched belts will slip, wear unevenly, or seat incorrectly.
A double groove pulley allows you to run two belts in parallel, which increases the total power transmission capacity of the drive. This is useful when a single belt would be overloaded, when you need redundancy so the machine keeps running if one belt breaks, or when you want to reduce belt tension per belt to extend belt life. It also helps balance side loads on motor bearings.
Aluminum alloy pulleys are well-suited for light-to-medium duty drives such as workshop machinery, fans, pumps, and conveyors running O/Z section belts. For heavy industrial drives with high shock loads, continuous high-torque operation, or abrasive environments, cast iron or steel pulleys may be more appropriate. For typical motor-driven workshop equipment, aluminum provides a reliable and durable solution.
These pulleys use a set screw for shaft retention and do not include a keyway as standard. If your motor shaft has a keyway and you require a keyed connection for high-torque or reversing applications, please contact us to confirm availability or consider having the bore machined with a keyway by a local machine shop after purchase.
Belt length depends on the center distance between your driver and driven pulleys and both pulley diameters. A common approximation is: Belt Length ≈ 2 × Center Distance + π/2 × (OD1 + OD2) + (OD2 − OD1)² / (4 × Center Distance). Measure your center distance and use this formula, then select the nearest standard O/Z belt length. Always check belt tension after installation and re-tension after the first few hours of running.
