Pulleys and Sheaves: An Ancient Solution to Modern Problems

Pulleys and Sheaves: An Ancient Solution to Modern Problems

Work has its ups and its downs. The sheave and pulley systems used in today’s cable pulling equipment are what you need to move your equipment and supplies, no matter which direction you are going. Handy knowledge of rigging products will help you choose the right tool for the job, no matter if you are hoisting heavy machinery to the upper floors, feeding wire, or sliding materials into their precise location.

While the design of pulleys has evolved over the centuries, the purpose and motion of pulley systems have not changed since their invention around 1500 BC in Mesopotamia. Archeologists have discovered that the earliest uses of pulley systems were to hoist water from wells and reservoirs, much the same as the pulley equipment we use today.

As our needs in construction have become more sophisticated, so too has our pulley technology, but the objective remains the same. Pulley systems were designed to exert a larger force through a short distance.

Therefore, less energy is needed to move a heavy object from point A to point B. Their versatility and ease of use is what has made them the tool of choice for construction for over thousands of years.

Of the three kinds of pulleys, the fixed axle is the simplest solution for lifting any number of heavy objects: pipes, wire belts, heavy machinery, and more. The fixed axle relies on one or more sheaves—otherwise known as the wheel of the pulley— that is anchored in place. A rope or belt glides along the grooved sheave and rotates the pulley. The mechanical advantage to a fixed axle pulley, like the Greenlee 658 Cable Pulling Tray Sheave, is that the force is evenly distributed on either side of the pully. Compare the fixed axle to the free axle pulley which is “free” to move without anchor; the free axle is used to multiple forces instead. It can be used to apply double the force to an object attached to the pulley. It is for this reason a tool like the Greenlee 8012 Cable Puller can withstand up to 8,000 pounds of force. Theoretically, that is enough power to lift an unladen forklift, although pushing the weight limits is not safe nor recommended.

Consider instead a compound pulley system. Compound pulley systems can combine the stability of the fixed pulley and the power of the free pulley. While it is uncertain when the first compound pulley system was invented, around the time of 287 BC writing from ancient historians note how the Greek inventor Archimedes was able to use a compound pulley system to move an entire warship laden with men. That is quite a feat! Benjamin Franklin would use the same pulley concept centuries later in colonial Philadelphia to hoist his new printing press up to the third floor when he discovered that the stairway was too narrow to carry it. Compound pulleys allow the operator to multiply the strength of several attached fixed and free pulleys to move a heavy load with the least physical effort.

"Compound pulley systems can combine the stability of the fixed pulley and the power of the free pulley."

Today, pulleys have been integrated into more sophisticated technology to meet our growing needs to lift, haul, and pull around the work zone: whether that be in the marina, the construction site of a multi-family housing development, or for industrial manufacturing. The Greenlee 6800 Ultra Tugger and Current Tools 88 Cable Puller are fixed pulleys that replace ancient manpower with modern electric motors to pull up to 8,000 pounds, or consistently 6,500 pounds. However, the price difference between motorized and non-motorized pulleys is night and day but may very well be worth the cost if you are looking for automated convenience.

Of course, the answer for how to stay on budget and design the ideal pulley system for your job application is purchasing reconditioned tools.

Compared to the newly manufactured price tag, with GES your business can save on half the cost without sacrificing quality or durability. GES’s collection of sheave assemblies and pulleys from trusted brands like Greenlee, Current Tools, Condux Tesmec, and Burndy is the tool-buying resource your business needs to meet customer demand without breaking the bank.

Since their inception, pulleys have become an essential tool for the job. Attached to an employee’s safety harness, pulleys can suspend a skilled welder on the upper floors of a high rise; or incorporated into heavy machinery, a crane can lift loads that exceed manpower alone; and compound pulley systems can transport and place heavy materials, like metal wires or pipes, throughout a construction project with half the cost of transportation labor. Find the pulley and sheave equipment solution you need today at GES, no matter the job and no matter the budget.

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