Pulley Construction

Overwhelmed by the breadth and depth of our line? Confused about the advantages and disadvantages of different materials and construction techniques? A little rusty on your pulley anatomy? Use this quick guide to help ease your selection woes!

Sideplates and Beckets. Sideplates form the overall body of the pulleym and together with the axle are primarily responsible for a pulley's overall strength. Beckets are installed in multi-sheave pulleys to provide a lower tie-in. Most pulleys have sideplates that rotate independently about the axle to make rigging easier. This allows rope to be rigged onto a pulley midstrand, rather than only at the ends.

Sideplates come in all shapes, sizes and colors depending on pulley function, but there are essentially only two choices of materials for sideplates: Anodized Aluminum or Stainless Steel. Anodized Aluminum is lightweight and durable, but not as strong. Stainless Steel is strong and weather resistant, but comparatively heavy.

Sheaves. The sheave (the wheel of a pulley) affects pulley performance in two ways: rope capacity and efficiency. Sheave width is the major factor in how large a rope a pulley can handle--wider sheaves handle larger ropes. Sheave diameter, along with bearing efficiency, determines the overall efficiency of the piece. In general, larger sheave diameters produce greater pulley efficiencies.

Stainless steel sheave are strong and resistant to wear, but heavy. They are excellent for use with steel cable. Aluminum sheaves are lightweight but wear quickly when exposed to abrasive materials in ropes. Glass-filled Celcon sheaves are are self-lubricating--no bushing or bearing is needed--but are weaker than other types of sheave. Nylon sheaves are lightweight and self-lubricating, and stronger than glass-filled celcon sheaves.

Bushings and Bearings. The Bushing or Bearing is the load bearing member between the sheave and axle.

A Bushing spreads the load over a larger area of axle, sliding the load around he pulley. This results in greater transfer, very little wear, and extremely long life. However, the greater area in contact results increased friction, decreasing efficiency.

Bearings decrease the amount of surface area in contact with the axle, which creates a more efficient transfer. By rolling the load around the axle, load on the transfer point is increased, which results in faster wear and shortens the life of the pulley.

Axles. In contact with all the other parts of the pulley, the axle is the primary determinant of the overall strength. Our special corrosion resistant nuts round out the package, ensuring a lifetime of resistance to the elements. Steel: High strength and good resistance to the elements, but heavy. Aluminum: Lighter, but not as strong or weather resistant. Hardened and Ground: Longest lifetime of any axle. Zinc Plated Steel: A less expensive option.