Early gears were made of wood with cylindrical pegs and were often
lubricated with animal fat grease. Gears were used in wind and water
wheel machinery for decreasing or increasing the provided rotational
speed for application to pumps and other powered machines. With the
onset of textile industry, the wooden gears were widely used to increase
the rotational speed of water to a usable level. The invention of mechanical clock gave a great stimulus to the development of mechanisms that used metal gears. Even after that the use of wooden gears for the transmission of wind and waterpower was continued.
Manufacturing
Wooden gears are made by making a blank out of wood, drilling the shaft hole and filling a keyway in the wood. Then using a gear train at slow speed long pieces of brass shim stock trimmed to the width of the gear is fed in between a pair of moving gears. This forms the brass with the proper gear tooth shape. The brass with the tooth pattern is wrapped around the wooden blank, overlapped one tooth and soldered together. The wood with brass wrapped around it is then laid down on wax paper and the space between the brass teeth and the wood is filled with epoxy or fiberglass resin to harden the gear. It is then dried and trimmed up of excess epoxy.
Properties
Gears made of wood are not so durable but they run smoothly and are easier to repair. The gears made of wood require cutting the wood to carve out the teeth. Inserting individual teeth into a plywood wheel can make good gears. Using mahogany or hard wood for the wood gears lend good hardness for resisting wear. The weakness of using wooden gears is low strength and low dimensional stability.
Wooden gears are widely used in textile mills and other industrial operations. They are also used in clocks, flour mills and coal mines.
