Mechanical Advantage
How did people lift heavy objects before steam, electric, and fuel driven engines?

The answer is with the original power tool, the block and tackle, or pulley. Pulleys have been in use for thousands of years allowing humans to move large objects such as stones, cannons, and commodities that are far to massive for one person, or even a group of people handle. Pulleys also allow users to change the direction of their force. In other words, with the use of a pulley, one can pull down and cause an object to move up.
Pulleys were used extensively throughout Colonial America. They can be seen in the rigging of sailing ships as well as in the gunnery systems. Pulleys were used on farms and in mills to lift and move large bags of grain and other agricultural products. Pulley systems were also used in construction projects to lift raw materials to upper floors of buildings.

Above: Schematic diagram of the mechanical advantage exhibit.

 

An exhibit at the Publick House allows visitors to experience first hand, the mechanical advantage offered by pulleys. The wooden structure features various pulley set ups attached to fifty pound bags of "flour" which guests can lift by pulling ropes. Visitors will struggle to lift a bag attached to only one pulley while lifting bags connected to more complex pulley configurations with relative ease. This exhibit was designed and constructed by Dan Bauer Ph.D. and Bob Libutti '02 of Lafayette College.