A block and tackle is a system of two or more pulleys with a rope used to distribute weight in order to lift heavy loads. The pulleys are assembled so that one pulley remains stationary and the others are moved to distribute the weight and move the object. The more pulleys used the more weight is transmitted.
Introduction
Since my persona is a Privateer, my interests are directed towards naval engineering and sailing lore. The age of sail and tales of sailing the seven seas are fascinating to me. Many of the medieval traditions and technology of sailing lives on today and hasn’t changed much from the original concepts. One of these is the use of pulleys, most specifically the block and tackle. A block and tackle is a system of two or more pulleys with a rope used to distribute weight in order to lift heavy loads. The pulleys are assembled so that one pulley remains stationary and the others are moved to distribute the weight and move the object. The more pulleys used the more weight is transmitted. Essentially a block and tackle is a type of crane. The first cranes appeared in Greece from about the late sixth or early fifth century B.C.
A single pulley offers no mechanical advantage but only changes the direction of the pull. It is much easier to pull downwards than up. A compound pulley is a combination of two or more pulleys in a block. The mechanical advantage is equal to the number of pulleys used. With a compound pulley a man can lift more than the can by hand.
Parts of a block
Pulleys were often made from available resources such as wood, stone or metal. I decided to make my block and tackle out of wood entirely since I am much more experienced with working with wood than metal or stone. I began by deciding on the size and shape of the pulleys and cutting out the basic shapes. I used modern tools because I am impatient and wanted to see results quickly.
Materials and Tools in period
- Wood
- Bronze
- Iron
This is an example of a bronze sheave, or wheel of the pulley salvaged from the ship The Mary Rose.
Materials and Tools I used
- Modern pine wood
- Wood glue
- Hemp rope
Drill, table saw, bandsaw, router, and belt sander.
Sources
“Artefact Gallery Page 5.” The Mary Rose, maryrose.org/the-artefacts/5/.
“Block and Tackle.” Wikipedia, Wikimedia Foundation, 19 June 2019, en.wikipedia.org/wiki/Block_and_tackle#Mechanical_advantage.
“The Sky Is the Limit: Human Powered Cranes and Lifting Devices.” LOW, www.lowtechmagazine.com/2010/03/history-of-human-powered-cranes.html.