A universal joint, U joint, Cardan joint, Hardy-Spicer joint, or Hooke's joint is a joint in a rigid rod that allows the rod to 'bend' in any direction, and is commonly used in shafts that transmit rotary motion. It consists of a pair of hinges located close together, oriented at 90掳 relative to each other, connected by a cross shaft.
History
The main concept of the universal joint is based on the design of gimbals, which have been in use since antiquity. One anticipation of the universal joint was its use by the Ancient Greeks on ballistae. The first person known to have suggested its use for transmitting motive power was Gerolamo Cardano, an Italian mathematician, in 1545, although it is unclear whether he produced a working model. Christopher Polhem later reinvented it and it was called "Polhem knot". In Europe, the device is often called the Cardan joint or Cardan shaft. Robert Hooke produced a working universal joint in 1676, giving rise to an alternative name, the Hooke's joint. Though the first use of the name universal joint is sometimes attributed to American car manufacturer Henry Ford, the term appeared in patent documents as early as 1884 when Charles H. Amidon was awarded United States Letters Patent No. 298,542 for a bit brace.
Other
A Constant Velocity Joints or CV joints are attached to each end of a drive shaft .
The CV joints are needed to transfer the torque at a constant speed to steered wheels as well as to accommodate up and down motions of the suspension.
You will find CV joints in all front-wheel drive cars. Many rear- and four-wheel drive cars and trucks have CV joints as well. The CV joint is packed with grease and protected by the rubber or plastic boot.
It does not require any maintenance and supposed to last very long provided that protective boot will not get damaged.
There are two most commonly used types of CV joints: ball-type and tripod-type. Different variations of ball-type CV joints are commonly used on the outer side of the drive shaft, while tripod-type CV joints mostly used on the inner side. Most common problem with the CV joints is when the protective boot gets damaged. Once this happens, the grease comes out and the moisture and dirt come in, eventually causing the CV joint to fail due to lack of lubrication and corrosion.
If a damaged boot caught early, simply replacing the CV joint boot and repacking the CV joint with fresh grease may fix the problem. If continue driving with broken boot, the CV joint or a whole drive shaft will need to be replaced. In worst case, the CV joint may disjoin causing the vehicle to stop running.
A clicking or popping noise when turning is the one of the indications of CV joint problems.
本文转自：China Industry News
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