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A breaker bar (also known as a power bar) is a long non-ratcheting bar that is used with socket wrench-style sockets. They are used to break loose very tight fasteners because their additional length allows the same amount of force to generate significantly more torque than a standard length socket wrench. [1] : 1, 3 Their use prevents damage to the ratcheting mechanism of a socket wrench. Often, after the first half turn, the fastener is loose enough to be turned with a socket wrench.
The long handle on breaker bars compared to shorter wrenches allow a larger torque to be generated with the same amount of force. Also, the absence of a ratcheting mechanism makes a breaker bar considerably stronger than a ratchet. This allows greater torque to be applied to a fastener without the tool failing. A breaker bar can be improvised by inserting a wrench into a length of metal pipe to increase the available torque. A pipe used for this purpose is called a cheater bar or snipe.
A breaker bar is able to create a larger amount of rotational force compared to a standard socket wrench. A standard breaker bar is strong enough to allow the user to apply up to 2500 pound-feet of torque without breaking the bar. [2] A high-end 1/2" socket wrench can withstand a maximum of 500 pound-feet of torque. [3] Since the breaker bar creates and withstands a larger amount of torque it is often used in place of a standard socket wrench to break loose tight-fitting fasteners. To be able to create these high torque numbers breaker bars have to be made out of a metal of adequate strength properties.
High-quality breaker bars are typically made of chromium-vanadium steel (AISI 6150). [4] Chromium-vanadium steel is known for its high strength, excellent toughness, and shock resistance. [5] Chromium vanadium steel has a yield strength at 0.2% offset of 84.0 kilo-pound per square inch (KSI). Meaning, chromium-vanadium steel can withstand up to 84 KSI before it begins to yield. [6] If the steel is unloaded before the yield point it is elastic and the material will return to its original configuration. Because of its high yield strength and shock resistance, standard socket wrenches, and breaker bars are fashioned from this material. In addition to its high yield strength, chromium-vanadium steel provides resistance to abrasion, oxidation, and corrosion making it a viable material for the production of tools. [5]
Rotational force, also known as torque, varies depending on where the force is applied. If the force is applied closer to the object the torque is smaller than if the same amount of force is applied further from the object. A breaker bar creates a larger force due to the amount of torque that can be applied through a longer handle versus a shorter one. A lever arm, also known as a moment arm, is an important factor to consider when measuring the torque of a breaker bar. Having a longer lever arm creates a larger surface area for the force to be applied, which increases rotational force. Surface area is the measure of the total amount of area an object occupies. When the radius of the moment arm is increased, the surface area is proportionally increased. [7]
The concept that torque is related to a larger moment arm is shown in the torque equation. The torque equation can be written as follows, Γ(Torque)=r(Radius)×F(Force). Since the force applied is multiplied by the radius of the moment arm, having a larger radius subsequently creates a larger torque. This makes the torque value on the point of rotation much greater as the size of the handle or moment arm increases. [8]
In physics and mechanics, torque is the rotational analogue of linear force. It is also referred to as the moment of force. It describes the rate of change of angular momentum that would be imparted to an isolated body.
A screwdriver is a tool, manual or powered, used for turning screws.
A torque wrench is a tool used to apply a specific torque to a fastener such as a nut, bolt, or lag screw. It is usually in the form of a socket wrench with an indicating scale, or an internal mechanism which will indicate when a specified (adjustable) torque value has been reached during application.
Torx is a trademark for a type of screw drive characterized by a 6-point star-shaped pattern, developed in 1967 by Camcar Textron. A popular generic name for the drive is star, as in star screwdriver or star bits. The official generic name, standardized by the International Organization for Standardization as ISO 10664, is hexalobular internal. This is sometimes abbreviated in databases and catalogs as 6lobe. Torx Plus,Torx Paralobe and Torx ttap are improved head profiles.
Carbon steel is a steel with carbon content from about 0.05 up to 2.1 percent by weight. The definition of carbon steel from the American Iron and Steel Institute (AISI) states:
A bolted joint is one of the most common elements in construction and machine design. It consists of a male threaded fastener that captures and joins other parts, secured with a matching female screw thread. There are two main types of bolted joint designs: tension joints and shear joints.
A socket wrench is a type of spanner that uses a closed socket format, rather than a typical open wrench/spanner to turn a fastener, typically in the form of a nut or bolt.
A cheater bar, snipe, or cheater pipe is an improvised breaker bar made from a length of pipe and a wrench (spanner).
In the field of solid mechanics, torsion is the twisting of an object due to an applied torque. Torsion is expressed in either the pascal (Pa), an SI unit for newtons per square metre, or in pounds per square inch (psi) while torque is expressed in newton metres (N·m) or foot-pound force (ft·lbf). In sections perpendicular to the torque axis, the resultant shear stress in this section is perpendicular to the radius.
An impact wrench is a socket wrench power tool designed to deliver high torque output with minimal exertion by the user, by storing energy in a rotating mass, then delivering it suddenly to the output shaft. It was invented by Robert H. Pott of Evansville, Indiana.
An impact driver is a tool that delivers a strong, sudden rotational force and forward thrust. The force can be delivered either by striking with a hammer in the case of manual impact drivers, or mechanically in the case of powered impact drivers.
A screw is a mechanism that converts rotational motion to linear motion, and a torque to a linear force. It is one of the six classical simple machines. The most common form consists of a cylindrical shaft with helical grooves or ridges called threads around the outside. The screw passes through a hole in another object or medium, with threads on the inside of the hole that mesh with the screw's threads. When the shaft of the screw is rotated relative to the stationary threads, the screw moves along its axis relative to the medium surrounding it; for example rotating a wood screw forces it into wood. In screw mechanisms, either the screw shaft can rotate through a threaded hole in a stationary object, or a threaded collar such as a nut can rotate around a stationary screw shaft. Geometrically, a screw can be viewed as a narrow inclined plane wrapped around a cylinder.
The SAE steel grades system is a standard alloy numbering system for steel grades maintained by SAE International.
A hydraulic torque wrench is a power tool designed to exert torque on a fastener to achieve proper tightening or loosening of a connection through the use of hydraulics. A torque wrench is applied to the nut either directly or in conjunction with an impact socket. Hydraulic torque wrenches apply a predetermined, controlled amount of torque to a properly lubricated fastener.
A screw and a bolt are similar types of fastener typically made of metal and characterized by a helical ridge, called a male thread. Screws and bolts are used to fasten materials by the engagement of the screw thread with a similar female thread in a matching part.
A nut is a type of fastener with a threaded hole. Nuts are almost always used in conjunction with a mating bolt to fasten multiple parts together. The two partners are kept together by a combination of their threads' friction, a slight stretching of the bolt, and compression of the parts to be held together.
A bolt is a form of threaded fastener with an external male thread requiring a matching pre-formed female thread such as a nut. Bolts are very closely related to screws.
A hex key is a simple driver for bolts or screws that have heads with internal hexagonal recesses (sockets).
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