What is a Universal Joint？Types and Function
Universal joint introduction:
What is a universal joint?
Universal joint is a mechanism for variable angle power transmission, used to change the direction of the driveline, which is an automotive drive system “Joint” parts. The universal joint combined with drive shaft is called universal joint drive. On vehicles with front-engine rear-wheel drive, a universal joint drive is installed between the transmission output shaft and the final Transaxle input shaft; on vehicles with front-engine front-wheel drive, the propeller shaft. is omitted and the universal joint is installed between the front CV Axle and the wheels, both driving and steering.
The universal joint is subjected to a variety of forces (torsional, centrifugal, etc.) during high-speed movement. It is also in a hard-acting area and is subject to harsh working conditions. It is easily worn out and is a fragile part. In use, grease should be injected into the grease nipple after every 1000 kilometers of driving to maintain good lubrication. Under normal conditions, the universal joint has a service life of 100,000 to 120,000 km, but due to the short service life of the four needle roller bearings on the cross shaft, the bearings are normally not replaced separately, but with the complete cross universal joint. When it is sold and supplied, it is supplied as an assembly, not as a cross shaft or bearing, so the useful life of the universal joint assembly is only 50,000 to 60,000 kilometers.
Universal joint material:
Manufacturing material The universal joints are typically manufactured from 20MnVB or 20 0CrMnTi alloy steel
Universal joint function
The universal joint is the main component of the universal joint drive axles and is used to connect the angled two shafts (the output shaft of the transmission and the input shaft of the transaxle). While rotating, the driven shaft is allowed to swing at an angle that still normally transfers torque to suit the vehicle’s needs in bumps and vibrations.
Universal Joints Manufacturing Video In Factory
Universal joint types
universal joint transfers power between the driving shafts, even if the rotating shafts are not inline. Common universal joints include Cross Universal Joint, CV joint, and tripod universal joint. The Cross Universal Joint is commonly used for passenger and cargo vehicles and the CV Joint are common for cars
Cross Universal Joint
The cross universal joint consists of a universal joint yoke, a cross shaft, a needle bearing, an oil seal, a sleeve, a bearing cap, etc. The needle rollers in the needle bearings rotate during cross-axial joint rotation to reduce friction. The shaft connected to the input power is called the input shaft and the shaft that delivers power through the universal joint is called the output shaft.
The CV Joint varies according to the inner and outer raceway structures and is divided into telescoping and fixed. Telescopic CV Joints are generally used for inner universal joints and fixed ball cage universal joints are generally used for outer universal joints.
The CV Joint mainly consists of outer star wheel, ball cage, steel ball, inner star wheel, etc. The spherical housing is the outer track of the ball and the Star type shell is the inner track of the ball. Power transfer path: Halfshaft (Drive shaft) → Star type shell → steel ball → ball housing → wheel center shaft (driven shaft).
The CV Joint construction is similar to the ball bearings, all made up of balls, retaining brackets, inner and outer tracks, but the shaft connected to the inner star housing of the universal joint can swing and retract.
Telescopic CV Joint
It is an inner universal joint that is bolted to the propeller shaft of the differential gear. This universal joint has a certain amount of axial retraction, to compensate for the variation in the axial length of the half shaft when the front wheels are runout. The U-joint transfers the torque through a steel ball with less resistance to axial movement.
Fixed Telescopic CV Joint
For outer universal joints, it cannot be telescoping in the axial direction, but it swings at a large angle to accommodate the run-out of the front wheels of the independent suspension; the end of the ball shell is a splined shaft which mates with the front hub.
tripod universal joint
The tripod universal joint has the advantages of simple construction, small size, and lightweight, and is therefore widely used in the front and rear drive axles of automobiles. When the barrel housing is turning, the ball wheel will pull the tripod shafts to follow it, and the three pivots are splined to the driven shaft, which in turn will spin the driven shaft for power transfer.
Universal joint boot and clamp
The universal joints need to be lubricated with grease, and the boot prevents dust and sand from splashing into the joints to damage their lubrication. Universal joints require regular maintenance, replace special grease, check for cracked boots, and loose clamps.
- On the one hand, it is objective and natural wear, because the universal joint and the drive shaft are assembled to transfer torque, in a working environment with high speed and force, and the parts are inevitably worn, which is objective
- On the other hand, factors such as human factors, driving technique, and maintenance, failure to follow operating procedures, rude behavior, lack of timely maintenance, and increased damage to parts.
- If the chassis makes an unbroken “snap” sound when the vehicle is moving when it suddenly increases, decelerates, or steers, the universal joints may be running out of oil or damaged.
- In addition to the universal joints applied to the driving system, the steering column of the steering system applies the universal joints to transfer steering forces between shafts with varying shaft lines. For ease of removal and installation, tools such as universal joints and spark plug wrenches are also applied to universal joints.