Doughty Double Sheave Pulley
Product No. T42801
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Double Sheave Pulley
The Doughty Pulley system is of modular construction, allowing easy assembly of double-sheave pulleys from a limited range of standard components. It is designed for use within the theatre, film and TV Industry. With the addition of various brackets and fixings, the basic pulleys will fulfill a variety of specialist needs. Sheaves are available for fiber or wire ropes.
All Standard Doughty Pulleys have a safe working load of 331 lbs. A basic single sheave pulley is ready to accept any of the range of fixings. 3 sheave sizes are available - 4'', 6'' and 7'' diameter.Features & Specifications
- Sheave Dimensions: 4'', 6'' and 7'' Diameter
- Sheave Material: Nylon
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The recommended sizes for Hand Ropes & Wires are:
- 4'' Diameter Sheave: 0.5'' Rope OR 0.16'' Wire
- 6'' Diameter Sheave: 0.7'' Rope OR 0.24'' Wire
- 7'' Diameter Sheave: 0.7'' Rope OR 0.24'' Wire - Width: 2.1''. Same for all sizes
- SWL: 331 lbs. Same for all sizes.
SHEAVE VS PULLEY
Pulleys have been around for a long time to lift a heavy load easier via the system of ropes and wheels. SHEAVE and PULLEY are sometimes used interchangeably, but technically they are not the same.
SHEAVE: As a part of the pulley system, it is the rotating, grooved wheel inside the pulley. This is the part where a rope/wire fits into.
PULLEY: It is one of six types of simple machines. This is a system consisting wheel(s) over which a rope/wire can be pulled to change the direction of forces and make lifting easier. It allows loads to be lifted using much less force than would normally be applied.
DOUBLE-SHEAVE PULLEY OR MULTI-SHEAVE?
Basically, the more sheaves you use on the pulley system, the easier the work it is. It is because each additional sheave used in a pulley enables you to exert half of the original required force to lift a load.
Although using multiple sheaves gives you a mechanical advantage, it also adds friction. The added sheaves and ropes/wires may increase friction and take away your mechanical advantage. The work ends up even harder. You can use several sheaves in one pulley system, but to increase efficiency you should arrange the sheaves above or below each other with a fixed axle between them.
Doughty Engineering is a UK-based entertainment equipment manufacturer and began the manufacture of products in 1985. Now, it is one of the world’s leading manufacturers of rigging, suspension and lifting equipment for film/TV, theatre and concert halls.
Quality and safety are key issues for Doughty. As a member of PLASA (Professional Light and Sound Association) and ESTA (Entertainment Services and Technology Association), Doughty adheres strictly to the standards of trading expected.