What’s an Extension Bar?

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An extension bar is a metal tube that extends the reach of a socket wrench up to 12cm or more, commonly used by mechanics to reach bolts in compact spaces. It fits between a socket bit and a wrench, allowing full torque transmission. It is different from a breaker bar, which extends the length of a wrench’s handle to increase torque. Extension bars are finely twisted to fit the end of the wrench and socket, with a common diameter of 3/8 inch. They are often used with spark plug sockets for easy removal.

An extension bar is a long and usually solid piece of metal tubing that allows the user to extend the reach of a socket wrench up to 12cm or more. They are commonly employed to help reach bolts that are recessed or otherwise unreachable with a standard wrench. They are often used by mechanics and other related professions, who need to loosen stiff or rusted bolts and work in compact spaces, such as engine compartments.

An extension bar fits between a socket bit and a wrench and allows the full torque created by one turn of the wrench to be transmitted along its length. This is invaluable in cases where, for example, a bolt in the bottom of an engine may have originally been installed at the factory, before the engine itself was installed. With the engine in place that bolt would become impossible to reach by hand or an unmodified socket wrench.

Extension bars are commonly confused with wrecking bars, as both are often associated with garage jobs. They are very different tools, however, and certainly not interchangeable. While an extension bar adds effective length to the tip of the socket for easier reach, a breaker bar extends the length of a wrench’s handle, increasing the maximum possible torque with one turn.

A switch bar plays into how torque works, which is rotational force calculated as horsepower times distance. This is important because, with hand tools, there is a physical limit to how much power a human can apply, determined by his or her own strength. Once this limit is reached, the only way to increase torque further is to increase distance. This is known as mechanical advantage.

While a breaker bar, essentially, can be any long, hollow piece of metal extrusion that fits over the handle of a wrench, an extension bar must be finely twisted to fit both the end of the wrench and the socket. The most common diameter for connectors between these various parts is 3/8 inch (1 cm), although larger and smaller sizes are available.

A common use of an extension bar is with spark plug sockets. Spark plugs, which are an integral part of the ignition system in an internal combustion engine, require periodic replacement and must be unscrewed from their location in the engine, not unlike changing a light bulb. However, candlesticks aren’t always easy to reach or exploit. In these cases, a special spark plug socket with rubber grip padding can be connected via an extension bar to a socket wrench, in order to easily loosen and remove the spark plugs.




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