What is a CV joint tripod. How to choose a tripod

The CV joint, or constant velocity joint, is a mechanism by which the transmission of torque from the transmission system to the wheels is ensured. In this case, the traction is transmitted to the driving steered wheels without loss of power. The mechanism allows you to provide turns 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 characteristics of axial movements. Paired gimbals are not particularly popular due to their complex design. Ball joint is most common on front wheel drive vehicles. These are installed on models from AvtoVAZ.

Hinge function and location

A fairly small number of motorists know what these nodes are, what they are intended for. And even more - in various forums, this detail has many names.

In the second half of the last century, front-wheel drive cars began to be developed, which required reliable drive to the drive wheels. Here the invention of the constant velocity joint (CV joint), patented in the 20s, came in handy. Today, almost all cars and SUVs coming off the conveyors have a tripoid (inner CV joint).

What is CV joint and why is it needed

Conventional universal joints could not cope with the task of turning the driving idler wheel. Their rotation was transmitted to the wheels unevenly, the loss of power when turning was significantly increased. The tires and the hinge itself wore out quickly. Shafts and other transmission components were overloaded.

The new hinge did not have such disadvantages. The force on the drive shaft was transmitted evenly, regardless of the angle between the shafts connected to it. This rather simple device can be used for a long time. It has great power when transmitting torque. No noise and vibration during operation. The ride and control in such a car is convenient and comfortable.

Internal and external hinge

To improve efficiency, front-wheel drive transmissions use internal and external joints called tripoids or tripods. The tripoids of the CV joint are usually universal; in some car models, needle bearings are used in the tripoids of the internal CV joints. They are equipped with rollers and a fork that allow axle offset and allow operation at angles not exceeding 20 degrees. In addition to the tripoids, there are also ball joints.

Typically, the speed control joint is:

a spherical body connected to the driven shaft;
a cage with a drive shaft;
separator for attaching and holding balls;
several balls in the separator.

Thanks to such light construction the torque is transmitted smoothly and smoothly, without loss of power. Such a hinge is quite reliable, and it is not difficult to replace it in case of failure.

How to save the CV joint tripoid

One of the problems of the CV joint is its imperfect lubrication mechanism. It is actually a boot in which the grease is stored. Given the vulnerability of this rubber or plastic product when it comes into contact with obstacles on the road, there is a risk of dust and dirt getting into it and, accordingly, into the tripoid. This inevitably leads to premature wear of the mechanism.

This question should not be left to chance. If fresh damage to the boot is found, the hinge should be removed and washed. Then put a new one and fill it with special grease. After checking the right boot, do the same with the left boot. The grease for the tripoid CV joint must have special qualities. It should prevent the destruction of the tripoid due to sudden loads on the hinge when the machine starts moving, climbing uphill, and sharp turns.

If such a material does not have the required characteristics, the mechanism quickly wears out and fails. For example, the use of a lubricant containing graphite is absolutely unacceptable. To lubricate tripoid CV joints, in addition to those with needle bearings, black grease is required, which contains 3-5 percent molybdenum disulfide. It must have the right consistency to completely fill the entire assembly.

Keeping the pivots at constant angular velocities is essential to ensure reliable transmission performance. In order not to find yourself in a difficult position, it is worth making the rule of periodic inspections of the anthers and their timely replacement with lubrication of the hinge. If the fastening clamps break and the boot breaks, the entire hinge must be replaced.

The rapid development of the production of cars with front-wheel drive was hardly possible without a hinge that makes the angular speeds equal, or SHRUS. Improving its application has given rise to discussions about which CV joint is better, tripoid or ball.

What is SHRUS for?

Today, CV joints are one of the most effective mechanisms that smoothly transmit torque from the engine without power loss through the gearbox to the driven drive wheels. Typically, the outer and inner hinges are attached to the splined shaft using thrust and retaining rings. The outer connects to the wheel hub. It transmits torque to the wheel and provides steering.

The inner one is adapted to axial movements and is installed on the drive from the side of the gearbox. Rotation is transmitted from it to the drive shaft. In this case, the speed of rotation of the input and output shafts are the same, it does not change depending on the angle of the hinge.

What are the differences between tripoid and ball

They differ from each other in that the ball has balls, dividing grooves or levers, and in the tripoid there are rollers with a spherical surface and a fork.

The hinge where the balls are used is usually:

body;
clip with grooves;
six balls in the grooves of the cage;
a separator holding these balls;
protective cover with CV joint grease.

This CV joint is connected to the drive shaft by means of splines.

The tripoid hinge has a housing that houses a three-beam fork. It is pressed onto the splines of the output shaft. Three rollers with a hemispherical surface, rotating on needle bearings, are mounted on the fork arms. Under them, grooves are cut in the tripoid body, due to which the desired angle of rotation of the hinge and the possibility of longitudinal displacement are created. The functions that it performs differ depending on whether the internal CV joint tripoid or the external one.

Thus, the main difference between the CV joints is that the first one rotates with the help of balls, and the second thanks to the needle bearings.

Which CV joint is better

On the Web, you can find many opinions of experts and car owners regarding which of the CV joints, tripoid or ball, perform better. Most of them point out the advantages of a tripoid CV joint:

the ability to work at a 45-degree angle without backlash and shock loads, ensuring sufficient wheel steering;
more reliable and durable, does not fail at once;
more longitudinal movement than ball, which allows you to compensate for the load;
when turning the hinge at a large angle, it resists loads better;
significantly more resistant to twisting;
low losses during axial movement and lightly lubricated needle bearings give it high efficiency;
ease of installation, replacement and maintenance due to sufficient space at the installation site;
excellent interchangeability with the same type of devices;
in tripoid fewer parts, cheaper to manufacture.

Reliability of CV joints

For long-term operation, the tripoid and ball CV joints are made of high-strength metals. This ensures the geometric accuracy of these mechanisms and the ability to transmit torque without loss.

Both types of hinges have increased sealing requirements. To do this, they are protected by a rubber or silicone sealed cover that protects the mechanisms from dirt, water and dust. This cover ensures long years of operation of the hinge. Its damage and untimely replacement leads to a quick failure of the CV joint.

Tripoids, which can break even as a result of small amounts of dust and dirt, require constant attention.

Automotive mechanics is a tricky business. You have to master it throughout your life and every time in a new way (in the event that you suddenly decide to buy a new car of a brand you are unfamiliar with). Today we want to help you master the features of another car part - a tripoid bearing. If on the fly you did not manage to understand which bearing we are talking about, do not worry. We are talking about an internal constant velocity joint (constant velocity joint), which has a special design called "tripoid". Breakdowns of this part do not occur so often, however, it takes a lot of effort to fix it. Below we will try to tell you in as much detail as possible about this slightly intricate bearing and what to do if it fails.

1. What is a tripoid bearing and where is this car part located?

According to our mini-survey of motorists, it was found that not everyone knows about the tripoid bearing and the purpose of this part. Moreover, as a result of our travels through the vastness of the Internet space, it turned out that this detail is not called as soon as: the tripod SHRUS, and the inner SHRUS, and the tripoid, and just a "grenade". But whatever the name, in this situation we are talking about, with which we have already introduced you in previous articles on our blog.

But, as we have already mentioned in our little introduction, a tripod or tripod bearing is a special design of the constant velocity joint, which is most often installed on the car from the drive side (by the way, this is the answer to the question of where the tripod bearing is located). Every car owner also needs to know that this bearing consists of spherical rollers and a fork, which allows for sufficiently large axial movements, while providing a non-linear change in speed at an angle.

What is the role of this detail, or rather the whole mechanism? Everyone knows that the movement of car wheels is due to the drive, which transmits rotation to them. However, if the angular velocity joints were not installed on the car, the wheels would stop turning when turning. And just the special design of the SHRUS allows you to change the angle between the axle shafts and keep the car moving regardless of the position of its wheels.

The CV joint was first invented back in 1927. It was patented by a mechanic named Alfred Rcepp, by whose name he was called for a very long time. Today, the name "pomegranate" is more common among motorists. This detail is a mandatory attribute of every front-wheel drive car, although it is also often found on rear- and all-wheel drive cars. In the latter case, this is done in order to make the rear gearbox mounting more rigid and the rear wheel suspension more independent.

2. How is a tripoid bearing or a conventional inner CV joint structure?

When we first have to deal with malfunctions of a given part, it turns out that we do not know much about it. Although the CV joint is quite simple in design, its placement and the complexity of possible breakdowns makes many car owners turn to specialists at the service station. We all know that this solution is not at all profitable from an economic point of view. Therefore, let's try to independently figure out the features of its design.

The CV joint has a very long working life, and under conditions of correct operation, its service can be very long. By the way, its work is somewhat reminiscent of the work of the knee joint, however, unlike the human body, it is not so difficult. The design of the outer hinge is almost identical to the inner one, and it consists of only 4 parts:

- the main body of the part, which is made in the form of a spherical bowl with a driven shaft;

Inside there is a clip in the form of a spherical fist with a drive shaft;

Cage, made in the form of a ring with special holes that allow holding the bearing balls;

The balls themselves, the number of which is usually six.

The only difference between a tripoid or an internal CV joint is that it is not a ball bearing, but a needle bearing. Moreover, there are as many as three planes on it, in which there is a corresponding number of needle bearings. That is, the base of the outer hinge is balls, and the base of the inner one is rollers with needle bearings. Regardless of whether the hinge is external or internal, a boot must be installed on top of it, preventing dirt from getting on the part itself and, thereby, ensuring its durability.

Unlike the usual CV joint with a ball bearing, the tripoid is a more "delicate" part. The ingress of even the smallest amount of dirt can immediately cause damage. Even the grease for needle bearings must be used specifically for them.

Also, the tripoids themselves may differ from each other in the degree of freedom that they transfer to the wheels from. In any case, all the functions of a tripoid bearing are reduced to ensuring a very smooth transmission of rotary motion. As you know, the cardan joint of the axle shafts, which is assigned the same function, does not have such an ability. Even if one axle shaft rotates evenly, then intermittent movements will still be transmitted from the cardan to the second.

3. Malfunctions of a tripoid bearing, which every car owner can face

At first glance, this part is not so important for the car, however, the tripoid is constantly under very heavy loads, and its malfunction completely immobilizes the car. In this regard, tripoids are made from very strong materials that are capable of being in service for a longer period. But still, for a number of reasons, breakdowns happen, and every driver should be able to respond to them correctly.

The very first reason that leads to such a result is associated with the aggressive driving style of the car owner. After all, the harder you press on the gas, the greater the load becomes, which is transferred to the drive, and from the drive to our tripoid bearing. The second reason for the occurrence of breakdowns is damage to the dust cover or just the boot of the inner hinge. As a result, a lot of dust and dirt begins to get on the part, friction inside the part mechanism increases, and over time it breaks down.

It is possible to understand that something is wrong with the operation of the tripoid bearing even earlier, as long as it does not fail directly during the ride. In particular, The first signs of impending serious troubles that can still be corrected are:

- the presence of vibrations in the movement of the car during its acceleration;

The presence of vibrations even when driving at speed;

A characteristic knock from the side when driving at low engine speeds.

If you observe this for your car, it's time to drive it into the inspection pit and carefully examine the CV joints, both internal and external. If there is even minor damage to the boot, driving such a car is already becoming quite dangerous. Any auto mechanic will advise you to remove the part from the car, disassemble it, rinse it, relubricate it and put on a new boot. How to do this, we will tell you.

4. Repair and replacement of the tripoid bearing.

If you have determined the presence of a malfunction at the very first stage of its appearance - you still have a chance to extend the life of the part without replacing it. If the needle bearings have had time to wear out and crumble, you will not have any options. We just remove the part, wash it and go to the auto parts store to pick up a similar copy for you. However, let's talk about everything in order.

How to remove a tripoid from a car?

First of all, you need to prepare: find a viewing hole or overpass for work, a standard set of tools for a motorist. Depending on whether you are going to repair the inner CV joint or replace it, you will need either grease and a new boot, or a new part. Let's get started:

- we drive the car to an elevation so that it is convenient for us to work with the CV joint;

Unscrew the mount - 6-8 bolts with which the hinge clips are screwed to the differential gears;

We take out the entire structure of the CV joint from its socket and from the shaft itself.

True, there is one more small nuance: after you have unscrewed the mount, be sure to turn the steering wheel to a position that will allow you to release the spline connections. Also, it is not always possible to easily and simply remove the part from its socket. Ideally, a special CV joint puller should be used. But not everyone has it and it is not so easy to get it, therefore motorists often use a hammer, a crowbar and their own strength. The main thing is not to overdo it, so as not to accidentally damage the part.

Certain difficulties also exist in order to properly remove the hinge from the shaft. To do this, you must unfasten the retaining ring and remove the boot clamps, which will also prevent you from removing the part. Unfortunately, on some car models, the hinge can be secured with a solid corkscrew, which cannot be removed without damage. Manufacturers do this on purpose - you have no choice but to go buy a new part.

Mechanics also advise removing two CV joints at once - internal and external. It is not only more convenient, but also safer. Do not repair parts directly under the vehicle. Better to get out to a workbench or table with good lighting.

We disassemble the tripoid itself and carry out its repair. What we do:

1. We remove the large and small clamp from the part.

2. We take out the boot and its inner part.

3. We take out the tripoid itself from the shell.

4. Using a screwdriver, remove the lock washer that secures the tripoid to the axle, and remove it.

5. We wash all the parts in gasoline to remove not only old grease from them, but absolutely all contaminants.

Next, you need to add new grease. We already mentioned that it has to be special and perfect for needle bearings. Today it is quite easy to purchase a lubricant that is designed directly for a tripoid CV joint, so you should not have any problems.

First of all, we need a clip from which we got our tripoid (it is also called simply "glass"). Inside it, you need to pour about 90 g of grease, leaving a little more in a standard bag. Next, we place the already cleaned tripod on the axle and insert it inside the holder, squeeze out the remaining grease from above. The optimal amount of grease loading for a regular car is 140 g.

It remains only to reassemble the part, install a new and whole boot on it, firmly fix all the clamps and install the unit back on the car. Even if the part was not completely new, it will extend its service life for a fairly long period of time, especially if you use your car with care.

As for the situation when the tripoid bearing is completely out of order, then its replacement is carried out according to the principle described above: we remove the old faulty part from the car and install a new one instead, having previously lubricated it with the required amount of lubricant. The main thing is that the new tripoid is identical to the old one, otherwise you will have to deal with a new breakdown, if not the next day, then the next week.

Tripod selection - a task no less important than choosing the camera itself... It is on the quality of the tripod that the quality of photographs will depend in cases where shooting from hand is impossible or difficult.

When will you need to shoot with a tripod?

The very firstwhat comes to mind is evening and night shooting... No matter how iron muscles and strong bones a photographer may have, he still cannot hold even the most compact camera absolutely still for several seconds. What can we say about more when the shutter remains open for 20-30 seconds, or even longer.

Second situationwhen you can't do without a tripod, it's when you shoot. Surprisingly, with a focal length of 400 millimeters, I managed to "blur" photos even at a shutter speed of 1/100 - 1/160. The problem here is that even a slight shift in the optical axis of the lens while the shutter is open leads to very noticeable movement in the frame. The result is a daub.

Another case is studio shooting... If you shoot a series of objects or models one after another, then it is advisable to set the camera in a certain position, which will remain unchanged throughout the entire photo session.

Well, and finally, the situation when, in order to avoid increased and other artifacts, it is required to lower it all the way and, as a result, increase the shutter speed. Although, this is a bit like what was covered in the first point.

Anyway, one fine day you will realize that choosing a reliable, comfortable, if possible not very heavy and, again, if possible, relatively inexpensive tripod.

If you go to a photography store, you will see entire counters filled with these wonders of engineering. The most important thing here is to decide

What tripods are there. Tripod types

Tripods - tripods

The first, most familiar variety is the tripod. That is, a tripod with three legs.

Tripods are made of wood. They are heavy, but wood is the best vibration dampener. In addition, the wooden tripod has some charm and a touch of antiquity and solidity. Decide for yourself - to carry you.

Others are made of aluminum. More compact, less heavy, inexpensive.

Some are made of carbon fiber or basalt. They are much lighter than aluminum ones, but more expensive. Decide again. Carry you.

Notice that there are tripods with tied legs (in the picture on the left) and unbound (center). For shooting in extreme conditions: in mountains, mountain rivers, on stairs and other irregularities, it is better to take unbound legs. In addition to being much more stable on a slope, they also provide a much lower "bottom point". This will be discussed a little later.

If the tripod is heavy, it does not vibrate or sway in the wind. Lightweight and cheap won't let you take crisp long exposure shots in the wind.

Tripods - monopods

This is a more mobile type of tripod.

Of course, this is a less stable support than a tripod, but there are times when there is simply no time to tinker with a tripod. For example, on an excursion to a museum or cave, or at a wedding. While you are arranging your tripod, the newlyweds will already sit in their cortege and leave.

Thus, a monopod is needed for operational shooting. Here the principle is at work - it's better to have a tripod than none at all.

Tripods - multipodes

This is a versatile option that combines a tripod and a monopod at the same time. They cost more, but you get a two-in-one device.

One of these tripods is discussed in detail in this article: Giottos Ball Head Tripod. Expensive, but exactly what you need!

Tripod - belt

This type of tripod is often used for video filming.

However, photographers sometimes use this option. Its advantage is high mobility. Here you don't even need a floor surface to shoot. You carry everything on you and take off. Of course, when photographing in terms of stability with a tripod, this option cannot be compared, but again the principle works: some kind of tripod is better than none at all.

Tripod selection criteria

Basically, these criteria are developed for tripod stands. Still, this is a much more common version of a stand for a photo and video camera.

1. The tripod must be suitable for the height of the photographer. The best option if you do not have to lean when aiming.

2. Look at the lowest position from which you can take a picture. The lower it is, the more opportunities you have. Flowers, mushrooms and other ground objects are filmed from low points.

3. The tripod should not shake at the slightest touch. If so, then in windy weather it will not be of any use to you.

4. Check how much weight the tripod can support. Perhaps over time you will acquire a camera with interchangeable optics, the weight of which sometimes reaches several kilograms.

5. Check the reliability of the tripod head. The head is the assembly to which the camera itself is screwed. If the head is loose, unstable, then it is better to refuse such a tripod.

6. The ends of the legs should have retractable spikes for shooting on ice. These are usually retractable spikes that can easily be pushed back inside the legs, giving way to rubber pads. Why should they clean up? For example, to place the tripod on a table, parquet or other glossy surfaces and not spoil them.

7. Removable platforms. It is very convenient if the tripod head is equipped with an easily detachable part to which the camera is screwed. Attaching such a platform in the field is much easier and faster than fooling around with screwing the camera to the head. It is desirable that there are two or three pads in the kit. One for a camera, another, for example, for a video camera, the third is a spare.

Well, and of course, the cost. Depending on your financial capabilities, try to immediately buy a good tripod and forget about this problem. It's much more economical than buying something cheap first. To suffer with it. Fuck up a couple of photo shoots, and only then buy a normal tripod.

Remember, the miser pays twice.