Universal joints allow the driveshaft to move up and down with the suspension as the axle moves, thus transmitting power when the driveshaft is not in a straight line between the transmission and the drive wheels. Rear-wheel drive vehicles have universal joints (or U-joints) at either end of the drive shaft. the U-joint is attached to the yoke and also allows the drive shaft to move backwards and forwards as the vehicle goes over bumps or depressions in the road, effectively shortening or lengthening the shaft. Front-wheel drive vehicles also use two joints, known as isometric (or CV) joints, but they are a different type of joint and also compensate for steering variations. On rear-wheel drive vehicles, one sign of a worn U-joint is a "clanking" sound when the drive gear is engaged. On front-wheel drive vehicles, the constant velocity universal joint usually clicks as it wears.
A universal joint is a variable angle power transmission mechanism used to change the direction of the drive train and is the 'joint' component of the vehicle drive system. A universal joint combined with a drive shaft is called a universal joint drive. On vehicles with front engine rear wheel drive, the universal joint drive is installed between the transmission output shaft and the final transmission input shaft; on vehicles with front engine front wheel drive, the drive shaft. Omitted, the universal joint is mounted between the front CV axle and the wheels for driving and steering.
The universal joint is subjected to a variety of forces (torsional, centrifugal, etc.) during high-speed movement. It is also in an area where it is difficult to function and is subject to harsh operating conditions. It is susceptible to wear and is a fragile part. In use, grease should be injected into the nozzle every 1000 km 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 bearings on the cross shaft, the bearings are generally not replaced separately, but with a complete cross universal joint . When sold and supplied, it is supplied as an assembly and not as a cross shaft or bearing, so the universal joint assembly has a service life of only 50,000 to 60,000 km.
The universal joint is the main component of the cardan drive axle and is used to connect the two shafts at an angle (the output shaft of the transmission and the input shaft of the drive axle). When rotated, it allows the driven shaft to swing at an angle that still transmits torque normally to accommodate the vehicle over bumps and vibrations.
Depending on the application, universal joints can be made from almost any material. Common materials include stainless steel, steel, naval brass and other similar alloys to handle greater torques and temperatures.
Plastics and thermoplastics are also used in the manufacture of universal joints because of their greater resistance to rust and corrosion as well as their electrical and magnetic insulation in the desired application.
Varying according to its material composition, type of hub and design application, a universal joint is a positive mechanical joint used to connect shafts.
Universal joints are most commonly found in the drive shafts of rear-wheel drive vehicles.
Specific applications for universal joints include aircraft, electrical appliances, control systems, electronics, instrumentation, textile machinery, medical and optical equipment, radio, weapons, sewing machines and tool drives.
Universal joints transmit power between the drive axles, even if the rotating axles are not coaxial. Common universal joints are the cross universal joint, the constant velocity universal joint and the tripod universal joint. Cross-joints are commonly used in buses and vans, and constant velocity joints are commonly used in cars.
Cross-joints
Cross universal joints consist of a universal joint yoke, a cross shaft, needle bearings, oil seals, sleeves and bearing caps. As the cross shaft joints rotate, the needle rollers in the needle roller bearings rotate to reduce friction. The shaft connected to the input power is called the input shaft and the shaft that transmits the power through the universal joint is called the output shaft.
Constant velocity universal joints
Constant velocity universal joints are divided into telescopic and fixed types, depending on the structure of the inner and outer raceways. Telescopic universal joints are generally used for the inner universal joints and fixed ball cage universal joints are generally used for the outer universal joints.
Constant velocity universal joints are mainly composed of outer star wheel, ball cage, steel ball and inner star wheel. The ball cage is the outer track of the ball and the star cage is the inner track of the ball. Power transmission path: half shaft (active shaft) → star cage → steel ball → ball cage → wheel centre shaft (driven shaft).
The structure of the constant velocity universal joint is similar to that of a ball bearing, both consisting of balls, cages and inner and outer tracks, but the shaft connected to the star housing inside the universal joint can be swung and retracted.
Telescopic universal joint
This is an internal universal joint that is bolted to the differential drive shaft. This type of universal joint has a certain amount of axial retraction to compensate for the change in axial length of the half-shaft when the front wheel jumps. u-joints transmit torque through steel balls and have less resistance to axial movement.
Fixed Telescopic Universal Joints
The outer universal joint is not axially retractable, but can swing at a large angle to accommodate the runout of the front wheels of the independent suspension; the ball housing ends in a splined shaft, which fits into the front wheel hub.
Tripod Universal Joints
Tripod universal joints have the advantages of simple structure, small size and light weight, so they are widely used in the front and rear drive axles of vehicles. When the barrel housing is rotated, the ball wheel will drive the tripod shaft to follow and the three pivot splines are connected to the driven shaft, which in turn rotates the driven shaft for power transmission.
You already know that your car cannot function safely or properly without good, sturdy wheels. What you may not know is that the wheel is far from a simple component. Actually, there is a lot of complexity that goes into the design of a wheel, and several components that must all be integrated together.
View More
A common frustration we hear from equipment users turning to us for assistance is that their universal joints don't hold up as expected. Low quality or poorly designed universal joints can result in loss of usefulness, partial machine malfunction, or complete universal joint failure.
View More
5 Common Questions About Wheel Hub Bearings
The more your shop knows about wheel hub bearings, the better you can serve your customers. Below, you'll find 5 common questions technicians have about wheel hub bearings.
View More
What Are Clutch Release Bearings?
If you've ever driven a manual vehicle, you'll be familiar with the process required to switch gears and apply power while the car is moving. But have you ever considered how the clutch, gear and power system in your car really works? And did you know, that at the very centre of every clutch operation is a particularly special component called a clutch release or throw out bearing?
View More
Clutch separation bearing 、Tapered roller bearing 