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What is a Mechanical Bushing?

11/5/2013 3:47:25 PM | by Anonymous


Mechanical bushings are sleeve shaped lining that are used to reduce the friction and wear between mechanical parts. They also help to constrain and restrain the motion of the parts. Sometimes, they are also known as a plain bearing. Mechanical bushings are used to line holes in stationary parts of a mechanism. They are particularly effective in spreading friction and wearing over the surface of the bushing as opposed to directing into a single spot.


A bushing is also known as a bush is an independent plain bearing inserting into a housing to provide a bearing surface for rotary applications. This is the common form of a plain bearing. The common designs would include split, solid and clenched bushings. They are only a “sleeve” of material with an inner diameter, length and outer diameter.


The difference between the three is that a solid sleeved bushing is sold all the way around and a split bushing has a cut along its length. The clenched bearing is similar to a spit bushing but instead with a clench across the cut. A flanged bushing is a sleeve bushing that has a flange at one end that is extended radially outward from the outer diameter. The flange is used to locate the bushing positively when it is installed to provide a thrust bearing surface.


A linear bushing is not usually pressed together into housing. Instead, they help to secure it with a radial feature. Two examples would include two retaining rings or a ring moulded into the outer diameter of the bushing that matches with a groove in the housing. This is more durable to retain the bushing because the forces acting on it can help to press it out.


The basic elements of bushing mechanics would consist of a shaft running through a hole lined with a mechanical bushing or rotating rod. The rod is able to rotate inside the mechanical bushing with the bushing relieving the rod of the friction and wear that is generated by the rotation.


Within an internal combustion engine, an example of the typical lubricated rolling mechanical bushing/ plain bearing would be the crank shaft. The piston rods are connected to the rotating crankshaft with the rotation pushing the pistons up and down. The connecting point of steel piston rod and polished steel shaft is a hole in the role that is aligned with the bushing. The mechanical bushing gets assistance from the lubricating action of engine oil by dissipating the friction of the rotating shaft.


One example of a non lubricated mechanical bushing would be the use of propeller shaft on a boat with an inboard engine in the through hull fittings. The propeller shaft runs from the transmission, through a hole in the hull followed by into the water. This hole or fitting is lined with anti corrosive polymers or bronze bearings that dissipates the friction and reduces the wear and tear on both the shaft and the hull. Additionally, the fitting is also designed to prevent water from entering the boat.


White metal also known as Babbitt meal together with plastics are used way more often than any other materials during the manufacture of mechanical bushing due to their effectiveness of reducing friction as well as their light weight and their low cost. Other materials used in ordinary mechanical bushing also include rubber, carbon, aluminium, bronze and many other various ceramics.


A plain bearing or mechanical bushing should not be confused with a regular bearing. The regular bearing is usually constructed of durable materials that are less inclined to be lubricated as opposed to introducing lubrication. They are also often a moving part in itself as in the case of a typical ball bearing.

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