What is a UNIVERSAL JOINT – Cardan or Constant-velocity Joint?
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What is a UNIVERSAL JOINT – Cardan or Constant-velocity Joint?


in this video we will explain what a
universal joint is we will show the difference between card and joints and
constant velocity joints and we will see where universal joints are used the
universal joint is a mechanical device that allows one or more rotating shafts
whose axes are inclined to each other to be linked together allowing the
transmission of torque and rotary motion for this reason universal joints are
classified as torque transmission devices the invention of this type of
joint dates back to the 3rd century BC thanks to some Greek scientists such as
Philo of Byzantium who mentioned this type of joint in his work bellow puakea
but it is only in 1545 that the famous italian mathematician and physicist
Gerolamo Cardano rediscovered this important device which is also called
cardan joint the universal joint consists of an intermediate cross pin
member simply known as the cross the size of the cross is determined in order
to obtain the best compromise between the dynamic features of the rotating
elements of the joint and the flexural properties of its pins the cross links
to yoke shafts together each pair of yoke is positioned at right angles to
the other the cross allows each yoke to rotate around the y and z axes the yoke
shaft connected to the engine is called input shaft while the other one is
called output shaft the input shaft transmits its rotational movement to the
output shaft the yokes are designed to overcome any elastic deformations and
they also keep aligned the bearing seats of the cross these yokes are usually
made of steel and they are manufactured to stringent quality and safety
standards the angle between the two shafts is called operate
angle with standard yolks which rotate for short periods of time it is possible
to reach an operating angle of 45 degrees while for continuous use an
operating angle of 35 degrees shall not be exceeded the transmission ratio of
the yolks does not remain constant over time but it has a smooth periodic
oscillation with a sine wave pattern this means that the speed of the input
shaft will never be equal to the speed of the output shaft the consequence of
this phase shifting causes vibrations the greater the operating angle the
greater the vibration will be to overcome these issues the double
universal joint can be used to accommodate the misalignment between two
parallel shafts the telescopic universal joint is however used in the
agricultural sector especially on vehicles such as tractors this consists
of two simple joints connected by a telescopic shaft which is able to
accommodate variations in length between the tractor and its attachment these
variations can occur during the tractor maneuvers due to the roughness of
natural terrain in the industrial sector the universal joint is used to transmit
rotary motion to many devices such as conveyor belts it can also be used to
operate the different cutters of a molder machine the constant velocity joint on the other
hand has a slightly different working principle it always links an input and
an output shaft together but unlike the universal joint this one has the ability
to keep the transmission ratio constant over time regardless of the rotation
angle of the shaft usually a constant velocity joint has an external
protection its heart is represented by the inner core through which the torque
and the rotary motion are transmitted the connection between the two shafts
takes place thanks to a series of steel balls placed one by one inside a cage
thanks to this cage the bells are free to rotate independently inside its
grooves allowing the articulation of the shafts as well as the transmission of
motion this type of joint is protected by a rubber boot a CV Gator usually
filled with molybdenum disulphide grease the rubber boot in fact protects the
joint from water and dust damages over time many people may not know what a
constant velocity joint is or what it is used for even though it is a very
important device for every vehicle constant velocity joints in fact are
mainly used in vehicles with front-wheel drive but also in several modern
rear-wheel drive cars with independent rear suspension in this last case these
joints are used at the ends of the rear axle half shafts or on the drive shafts
ten years in the industrial supply sector have led JAES to become a quality
partner for some of the most important mechanical joint manufacturers offering
a wide range of different joint types we can conclude by saying that in the
vast industrial sector from energy to food from agriculture to woodworking the
universal joint is a very important device which plays a leading role in the
modern industries all over the world finally if you found this video useful
let us know by leaving a comment and subscribing to our YouTube channel to
stay tuned on the latest release of new videos thanks for watching

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