What is a Universal Joint？Types and Function
Universal joint introduction:
What is a universal joint?
Universal joint, also called Cardan 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:
The most commonly used material for manufacturing Universal joints are 20MnVB and 20 0CrMnTi alloy steel. Both materials have excellent physical properties, such as wear resistance, high strength, good flexibility, and corrosion resistance. They are also cost-effective and widely available on the market. Furthermore, these materials can be machined easily with precision to achieve the tight tolerances required for universal joints in various applications.
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
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Universal joint types
universal joint transfers power between the driving shafts, even if the rotating shafts are not inline. Universal joints that without obvious elasticity in the torsion direction could be divided into
Variable Velocity universal joint
constant velocity(CV) universal joints.
and quasi-constant velocity universal joints
Variable Velocity universal joint
The cross universal joint is the commonly seen type of variable/non-constant velocity universal joint, it 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 roller bearing rotate during the cross universal 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.
CV Universal Joint
The Constant Velocity Universal Joint (CVUJ) allows two shafts to rotate at a constant speed, regardless of their angle or relative position. This makes them ideal for power transmission systems where the two shafts are subject to frequent changes in orientation and distance. CVUJs are most commonly found in automotive applications, such as in the drive train of a car or truck. They can also be used for industrial machines and other heavy-duty applications.
CVUJs are typically composed of two yokes connected by a central cross-shaped piece and four needle bearings for smooth operation. The yokes are connected to shafts, allowing them to rotate independently while still maintaining the desired velocity.
Rzeppa CV Joint
The Rzeppa CV Joint consists of six circular grooves cut into the inner portion of a casing and a set of steel balls that provide constant transmission speed. This makes it an excellent choice for manufacturers wishing to create powertrains with complex mobility requirements, as its design allows for smooth pivoting between shafts without any decrease in power output.
It is also particularly suited for harsh driving conditions, given that its components are highly resistant to stress and deformations such as twists or torque.
Fixed and Plunge Joints
Fixed and Plunge Joints are a specialized form of Constant-Velocity (CV) Joints commonly used in Front-wheel drive vehicles. The plunge joint is mounted on the inside end of the drive axle enabling angular movement between the wheels and providing a smooth driving experience.
The fixed joint is located at the opposite end outside the axle. It is designed to take power from the transmission and deliver it to the wheel hub assembly, allowing for solid acceleration.
Tripod Joints and Ball-Type Joint
Tripod joints typically feature three trunnions on their base and an internal cage to contain the rolling elements; its refined shape is perfect for dynamic vehicle movement while providing strength and stability.
Ball-type joint stands out due to their simplicity and inexpensive costs; it relies on a single steel ball shaped as a spherical triangle to transmit power in tightly curved scenarios.
Fixed Tripod Joints
Found predominantly on front-wheel drive vehicles, these joints have a unique design that sets them apart from other CV joint styles. A trunnion is mounted onto the outer housing of the joint, and three steel arms, or ‘legs,’ are connected in an arrangement reminiscent of a tripod which gives this type of joint its name. Due to their durable construction, fixed tripod joints often boast exceptional longevity compared to other CV joints making them the ideal choice for heavier-duty applications.
Useful Tips
- 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 ay 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.
