CV joint, or constant velocity joint, is a mechanism by which torque is transmitted from the transmission system to the wheels. In this case, the thrust is transmitted to the leading steered wheels without loss of power. The mechanism allows for rotations up to 70 degrees.
There are several types of CV joints that are used in front-wheel drive cars. Crackers are installed mainly on heavy trucks or buses. Tripoid CV joints are used in internal structures due to their axial movement characteristics. Twin universal joints are not particularly popular due to their complex design. The ball joint is most common on front-wheel drive vehicles. These are installed on models from AvtoVAZ.
Hinge function and location
About what these nodes are, what they are intended for, a fairly small number of motorists know. And even more - on various forums, this part has many names.
This is a tripoid CV joint, an internal CV joint, and a tripoid, often just a grenade. But,one way or another, this is a constant velocity joint, but with some design features. Often such mechanisms can be found on cars from the drive side. Also, every motorist should know that this part consists of spherical rollers and a fork. This design allows the node to move along the axis within a wide range, while providing changes in angular velocities.
What is the tripoid for?
The car can move due to the drive, which transmits torque to the drive wheels. But if there were no CV joints in the system, then at the moment the wheels turn, the disks would not be able to rotate. And due to the fact that the tripoid CV joint has certain design features, the angles between the axle shafts can change. As a result, the machine moves regardless of the position of the drive wheels.
The history of the invention of SHRUS
The CV joint was first invented in 1927. A patent for this mechanism was received by mechanical engineer Alfred Rzepp - for a very long time the design bore the name of this mechanic. Today, motorists know this device under the simple name - "grenade". This part is considered one of the main components for any front-wheel drive car. But CV joints are installed on rear-wheel drive cars, and even on all-wheel drive. In the case of all-wheel drive cars, the hinge is necessary to ensure greater rigidity of the rear gearbox. Also, due to the use of this element, independence in the rear suspension is ensured.
How the CV joint works
When it failstripoid CV joint on the VAZ Priore, it turns out that not every motorist knows enough about him. Although the design of the hinge is quite simple. But the place where it is installed, and complex breakdowns force the car owner to contact the service station for repairs. Naturally, this is not a good solution. It is worth understanding the design of the part yourself.
It must be said that the resource of the constant velocity joint is very high, and if you properly care for the mechanism and service it in a timely manner, it can work 200-300 or more thousand kilometers. The principle of its operation is somewhat reminiscent of the structure and operation of the human knee joint. But unlike the knees, the tripoid CV joint has a simpler design.
Ball Joint Device
Let's start with the external node device. The mechanism consists of a body in the form of a spherical bowl and a slotted hole for the output shaft.
Inside the case there is a clip resembling a spherical fist and a drive shaft. Also, the mechanism consists of a separator in the form of a ring with holes made in it to hold the balls. And, of course, the device also contains the balls themselves.
Tripoid bearing design features
Tripoidal CV joint differs from the usual one only in that the bearings in it are not ball bearings, but needle ones. The mechanism has three planes, where three needle bearings are installed. The outer hinge is based on balls. And in the inner - rollers with needle-type bearings. It doesn't matter, extern althe hinge or it is internal - an anther must be installed on top of the part. It protects the movement from dust and dirt.
Unlike traditional ball joints, internal tripoid CV joints are a more delicate mechanism. If even a small amount of dirt gets inside it, this can lead to failure of the part. Also differences in lubrication. It must be designed specifically for needle bearings. The other one doesn't fit here.
Features of tripoids
Tripoid CV joint, depending on the model, may have a different degree of freedom that this mechanism transmits from the transmission to the wheels. The functions of this node are reduced to ensuring the most even rotation. The same function is assigned to the universal joint of the semi-axes, but it does not possess such abilities. Even if one of the semi-axes rotates evenly, then the second torque is transmitted intermittently.
Due to the fact that needle bearings are used in the design, such mechanisms have a very high wear resistance. Also, the losses due to friction of the elements among themselves in the node are significantly reduced. Tripod CV joint 2110 can be bent at an angle of up to 18 degrees. As for the maximum axial movement, this figure is up to 55 millimeters. The mechanism is able to compensate for the vibration of the engine and gearbox by more than 60%. The peculiarity of the part is also that it cannot fail at one moment, leaving the car without the possibility of further movement.This is important for fans of off-road driving and trophy raids. Even despite the crackling sounds and vibrations, the part in emergency condition will make it possible to get to the service station.
Which CV joint is better?
There is no consensus among motorists about which design is better, so a lot of controversy arises on this basis. Some say that the tripoid CV joint is better, others - that the ball joint. At the same time, many emphasize the advantages of tripoid hinges.
So, these mechanisms are able to work with virtually no backlash at angles up to 45 degrees. The wheel can turn at sufficient angles. The advantages include high reliability and durability, large longitudinal movements, torsional stability, good efficiency. They also highlight the ease of installation, replacement and maintenance due to the large amount of space at its installation site. Still in favor of the tripoid CV joint, we can say that it is perfectly put in place of the ball joint and vice versa. Tripoid hinges have fewer parts in the design. Accordingly, the mechanism is cheaper to manufacture and costs less.
There is no doubt that it is better to purchase exactly tripoid hinges. They have higher performance and in the event of a breakdown will allow the car to get to the place of repair.
About tripod joint lubricants
Experts say that the lubricant for the tripoid SHRUS needs a strictly special one, designed for needle bearings. However, use 158 grease, which is just designed for needle bearings, categoricallyprohibited.
For its manufacture, lithium thickeners are used. It works at temperatures not higher than 120 degrees. Internal hinges can reach temperatures over 160 degrees. Lubricants for internal joints are liquid. They are recommended to be poured into the anther, which is installed on the drive, and then assemble the structure. Pour usually from 100 to 130 grams. More exact volumes are specified at the manufacturer.
Grease composition for modern hinges
Most often these products are based on mineral oils and additionally contain molybdenum disulphide as an anti-friction additive. Such a lubricant is black, and therefore many confuse it with graphite lubricants, which are categorically not suitable for CV joints. Ordinary "Litol-24" has weak anti-friction characteristics and is also not suitable for hinges.
Tripoid CV joint VAZ 2110 and other car models are recommended to be lubricated with special products based on barium. Their difference is the wider temperature ranges in which the lubricant can operate without loss of performance. So, it does not lose its qualities at temperatures from -30 to +160 degrees.
Typical malfunctions of tripoid joints and causes
These mechanisms are made of extremely durable materials that can be used for a long time. But for some reason, these nodes still fail.
The first reason is the aggressive driving style. The harder the driver presses the pedalaccelerator, the greater the load experienced by the drive and, accordingly, the tripod bearing. The second reason why the assembly fails is damage to the anther. As a result, dirt and dust enter the mechanism, thereby increasing friction. The first signs of a breakdown can be vibration when the car is moving or during acceleration. It can also be felt when driving at high speeds. Finally, knocks will be heard from the engine side when driving at low speeds.
If such signs are observed, it is necessary to go to a flyover or inspection hole and carefully diagnose the hinges. At the same time, it is necessary to examine not only internal, but also external mechanisms. If even slight damage to the anther is visible, then you cannot drive such a car. It may be dangerous. In this case, experts recommend dismantling the part, washing it, replacing the oil seal and installing it back. You can also install a completely new mechanism.
If you analyze the reviews of car owners, manufacturers' recommendations and the advice of professional auto mechanics, then you should install a tripoid SHRUS on the car. The ball assembly has less reliability, which means it will fail faster and require replacement. As for this process, those motorists who have minimal maintenance skills will cope with it. For repairs, it is not even necessary to have an inspection hole - just jack up the desired part of the car and disassemble the hub.
So we figured out whatrepresents a tripoid joint of equal angular velocities.