Collection: Pulley Sheaves
Pulley Sheaves
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Pulley Sheaves
Belt drive rigs live or die by the sheave ratio. Sun Brite Supply carries BK cast iron pulley sheaves and H style bushings for belt drive pressure washer pumps, and we will run your ratio math at the counter or over the phone. Call 301-519-9274 with your engine RPM and the speed your pump wants, and we will spec the sheave before you order anything.
How to Size a Pulley Sheave for a Belt Drive Pump
The math is short. Pump sheave diameter equals engine sheave diameter times engine RPM, divided by the RPM your pump is rated for. A gas engine turns about 3,400 RPM and most belt drive triplex pumps want around 1,450, so the pump sheave ends up close to twice the diameter of the engine sheave. Spin the pump too slow and you give up flow. Spin it too fast and you cook valves and seals, which is the expensive way to learn the formula.
Grooves, belts, and bushings
BK sheaves accept both A and B section V belts. An A belt is 1/2 inch wide and rides lower in the groove, a B belt is 21/32 inch wide and rides higher, so measure your belt before assuming the pitch diameter. One groove is fine up to roughly 5 HP of load. Two grooves cover the 5 to 15 HP range where most contractor skids live, and running two belts also cuts slip on cold starts. The sheave itself has a tapered bore. An H bushing drops into that taper, and the cap screws pull the two together to lock on the shaft. Buy the bushing bore to match your shaft, 7/16 inch for small engine shafts up to 1 inch for pump and jackshaft work. When a belt squeals or dusts black rubber on the frame, check alignment and tension first. A straightedge across both sheave faces and about 1/2 inch of belt deflection solves most of it.
What we carry
| Part | Type | Fits | Price |
|---|---|---|---|
| BK 1-Groove A/B Sheave | Single groove | A or B belt, H bushing bore | $41.95 |
| 2BK 2-Groove A/B Sheave | Double groove | Twin A or B belts, H bushing bore | $63.12 |
| H Bushing, 7/16" ID | Split taper bushing | 7/16" shafts | $10.12 |
| H Bushing, 1" ID | Split taper bushing | 1" shafts | $10.12 |
Need a diameter or bore you do not see here? Call us. We order odd sizes all the time.
Related Collections
- Pressure washer pumps, including belt drive solid shaft models
- Pumps Made Ready, assembled and tested before pickup
- General Pumps and CAT Pumps
- Gearbox reduction drives, the other way to slow a pump down
- Unloader valves and pump oil
- Pressure washer repair parts
- Local? Stop by our Gaithersburg pressure washer store
Frequently Asked Questions
What size pulley sheave do I need for my pump?
Divide engine RPM by the pump's rated RPM to get your ratio, then size the pump sheave that many times larger than the engine sheave. For a 3,400 RPM engine and a 1,450 RPM pump, that is a ratio of about 2.3 to 1. Call us with both RPM numbers and we will confirm the diameters.
Do BK sheaves work with both A and B belts?
Yes. The BK groove profile is cut to seat either one. Just remember the two belts ride at different depths, so the effective pitch diameter changes with the belt you choose. Never mix an A and a B belt on the same 2-groove sheave.
What is an H bushing and how do I pick one?
It is a split tapered insert that locks the sheave to the shaft. Pick the bore that matches your shaft diameter exactly, slide it into the sheave taper, and torque the cap screws evenly. The taper does the gripping, so there is no need for a press fit.
Why does my belt keep slipping or burning up?
Three usual causes: sheaves out of line, belt too loose, or a single belt trying to carry a two-belt load. Check alignment with a straightedge, set deflection to about 1/2 inch, and step up to a 2-groove sheave if you are pushing a big pump with one belt.