Pulleys are simple devices with many uses, and as an engineering expert, I’ve often incorporated them into mechanical designs. They’re used in machinery to transmit mechanical power from electric motors and engines to devices like blowers and pumps. Another common usage for pulleys is to aid in lifting. There are two types of pulleys for this purpose, simple or compound. We’ll start our discussion off by looking at the simple type today.
The simple pulley may have been an advanced application of the wheel. It consists of a furrowed wheel on a shaft with some device for pulling threaded through it. The pulley wheel supports and guides the movement of a rope, cable, or other pulling device around its circumference. The pulling device runs between a pull-ee and pull-er, that is, the object to be moved and the source of pulling power, with the pulley itself situated somewhere between them.
Pulleys are believed to have first been used by the Greeks as early as the 9th Century BC. We’ll look into how they put them to use next time.
Copyright 2016 – Philip J. O’Keefe, PE