In the late 1800s, engineers faced a growing challenge: how to reduce friction and ensure efficient torque transfer between a motor and its connected shaft. The solution came in the form of the keyed shaft—a simple yet effective mechanical design that revolutionized power transmission systems.

The concept is straightforward: the motor includes a built-in key, while the shaft features a keyway. When the key slides into the keyway, it creates a secure connection that allows for smooth motion transfer. This system minimizes the need for excessive tightening, reduces friction, and enhances torque efficiency. It became known as a "keyed joint."

Keyshafting is a variation of sprocket drive technology, where each tooth or cog on a driven shaft is matched with a corresponding component on another shaft or belt to transmit rotational force effectively.

Common Types of Keyed Shafts:

• Woodruff Keys: These are semicircular and fit into a matching pocket on the motor. They are often used in high-speed applications due to their balanced design.
• Parallel Keys: The most commonly used type, featuring a rectangular slot cut into the shaft. A male component slides into the keyway, and set screws are often used to secure the hub.
• Scotch or Dutch Keys: Simpler to manufacture, these are inserted by hammering a round or tempered key through a drilled hole in the motor and shaft. Known as "pins," they are ideal for basic applications.

How Keyed Shafts Are Made:

Creating keyways involves precise metal cutting. Here are some common methods:

• Keyseaters: Industrial machines that cut keyways using a rotating cutter, either moving the workpiece or the tool.
• Wire EDM: Used for small, high-precision parts, this method uses electric discharges to erode material from the shaft.
• Broaching: Involves pushing a broach against the shaft mounted in a press—more labor-intensive but precise.
• Milling Machines: Can produce various types of keyways, including parallel, Woodruff, and tapered.
• Chiseling: One of the oldest methods, now rarely used due to its time-consuming nature and lack of precision.

Pre-Keyed Shafting: Standardization and Convenience:

Shaft sizes have become highly standardized, with diameters ranging from 3/8 inch to 2.5 inches and lengths from 3 feet to 24 feet. They are typically made from carbon steel or stainless steel, and can be customized for specific equipment needs.

Pre-keyed shafts eliminate the need for on-site keyseating, saving both time and cost. Many come with collars that allow for easy coupling with machinery. These collars are also keyed and secured with set screws.

At The Big Bearing Store, we've been providing reliable power transmission solutions for over a decade. As one of the leading distributors of bearings and related components, we're here to help you find the right products for your application. Contact us today to learn more about our extensive range of pre-keyed shafts and other industrial components.