Cardan transmission

A cardan transmission is a component of a car that transmits torque between shafts located at a certain angle relative to each other. It is difficult to imagine a modern car without a cardan transmission of one type or another. Cardan drives are typically used in transmissions and steering. The name comes from D. Cardano, who described the device in the 16th century. However, the scientist only described the structure of the cardan, but he cannot be counted among the inventors of the cardan transmission. They brought to life what was described much later, several centuries later. And the name Cardano is now immortalized for centuries.

The following elements are connected using a cardan drive:

power unit and gearbox;
Gearbox and transfer case;
Gearbox and final drive;
transfer case and final drive;
differential and a driving pair of wheels.

The main element of the cardan transmission should be called the universal joint. It comes in various modifications:

equal angular velocities;
unequal angular velocities;
semi-cardan elastic joint;
semi-cardan inelastic joint.

Cardan transmission with unequal velocity joint

This type of transmission can be found on rear-wheel drive or all-wheel drive vehicles.
The structure of such a transmission is as follows: joints of unequal angular velocities are located on the cardan shafts. There are connecting elements at the ends of the transmission. If necessary, a connecting support is used. The hinge combines a pair of forks, a cross and locking devices. The fork eyes have needle bearings in which the crosspiece rotates.

Copy-paste:

On the carefully processed fingers of the crosspiece 3, steel glasses 13 with needle bearings 12 are installed. The bearing needles at the inner end rest on the support washer 11. The glass is sealed on the crosspiece with a rubber seal 10 installed in a metal housing 9, which is put on the crosspiece. The crosspiece with glasses is secured in the fork ears 2 and 4 with retaining rings or plates 6 with screws. The crosspiece bearings are lubricated through the central oiler 7, from which the oil reaches the bearings through channels in the crosspiece. To eliminate excess oil pressure, a housing with a safety valve 8 is threaded into the crosspiece.

Bearings cannot be repaired or serviced. Oil is poured into them during installation.

The peculiarity of the hinge is that it transmits unequal torque. The additional shaft periodically overtakes and lags behind the main shaft. To compensate for this deficiency in the transmission, several joints are used. The forks of opposite hinges are located in the same plane.

Depending on the distance over which torque must be transmitted, one or two shafts are used in the cardan transmission. When the number of shafts is equal to two, one of them is called intermediate, the second is called rear. To fix the shafts, an intermediate support is installed, attached to the car body.

The cardan drive is connected to other elements of the car using flanges, couplings and other connecting elements.

It is safe to say that unequal velocity joints have low reliability and a relatively short service life. In modern conditions, cardan drives with constant velocity joints are used.

Types of driveshafts

The main role in the cardan drive is played by the cardan joint, depending on the design of which the following types of cardan drives are distinguished:

transmission with constant velocity joint;
transmission with unequal velocity joint;
transmission with a semi-universal elastic joint;
transmission with a semi-cardan rigid joint.

By the number of shafts, cardan transmissions can be: single-shaft, double-shaft and multi-shaft, and by the number of hinges - single-joint, double-joint and multi-joint.

Cardan transmission with constant velocity joint

This type of transmission is widely used in front-wheel drive vehicles. It connects the differential and the drive wheel hub.

The transmission has two hinges - internal and external, connected by a shaft. CV joints are often used in rear-wheel drive cars and all-wheel drive cars. The fact is that constant velocity joints are more modern and practical, moreover, the noise level from them is much lower than from the CV joint.

The most common existing one is the ball-type constant velocity joint. The CV joint transmits torque from the drive shaft to the driven shaft. The angular speed of torque transmission is constant. It does not depend on the angle of inclination of the shafts.

The CV joint, or as it is popularly called a “grenade,” is a spherical body in which the clip is located. Balls rotate between them. They move along special grooves.

As a result, torque is uniformly transmitted from the drive shaft to the driven shaft under conditions of angle change. The separator holds the balls in the desired position. The “grenade” is protected from the influence of the external environment by a “boot” - a protective casing.

A prerequisite for a long service life of CV joints is the presence of lubricant in them. And the presence of lubricant, in turn, is ensured by the tightness of the hinge itself.

Separately, it is worth mentioning the safety of CV joints. If you hear a crackling or noise in the grenade, it needs to be changed immediately. Operating a car with a faulty CV joint is extremely dangerous. Simply put, the wheel may fall off. The reason why the driveshaft becomes unusable is most often the wrong choice of speed and poor road surface.

Cardan transmission with semi-cardan elastic joint

An elastic semi-cardan joint facilitates the transmission of torque between shafts located at a slight angle. This happens due to the deformation of the elastic link.

An example is the Guibo elastic coupling. This is a hexagonal compressed elastic element. The flanges of the drive and driven shafts are attached to it and torque is transmitted.

Cardan classification

Several types of driveshafts are used in the design of modern cars. They may differ not only from the manufacturer, but also from the type of car. Some identical models may have different types of gears.

Depending on the design, cardan drives can be:

Single-shaft - a more powerful type, often installed on all-wheel drive or rear-wheel drive vehicles. This mechanism allows you to transfer torque to the wheels as quickly as possible.
Multi-shaft is a more complex, but fragile mechanism that is present on most passenger front-wheel drive cars. In addition to the main shaft, an intermediate shaft is added (where the bearing is needed).

Operation of a multi-shaft cardan transmission
Based on the number of shaft supports, there are the following types:

Double-bearing - do not have an outboard bearing, mounted on trucks or four-wheel drive vehicles.
Three-bearing - have one bearing that connects the intermediate shaft and the main one. Applicable to most cars.
Four-bearing - have several intermediate shafts connected by two bearings. A rare variety, installed on some Lexus and Chrysler jeeps.

Based on design features, the following models can be distinguished:

With an NUS (unequal angular velocity) joint - a standard design installed on most cars with rear-wheel drive.
CV joint is a modern cardan transmission that maintains equal angular speeds.
Elastic semi-cardan joints.
Rigid semi-cardan joints.

Most modern front-wheel drive cars are equipped with a CV joint type driveshaft. It is more comfortable and less subject to vibration, which is important for passenger cars. However, such a system is more complex, it is not cheap to maintain and can easily break if not properly maintained.

Main malfunctions and their symptoms

The most durable mechanism in the design is the shaft itself. It is cast from a strong alloy that can withstand extreme loads. Therefore, you need to try hard to damage it. As a rule, these are mechanical damage due to an accident.

In general, the main faults can be divided into several types:

Vibration – when starting or moving, strong or weak vibrations may occur. This is the first sign of damage to the spider bearings. Also, the problem may indicate improper shaft balancing; this happens after mechanical damage.
Knocking – a characteristic knocking sound when moving from a standstill will mean that the fastening bolts or splines have worn out. In this case, it is best to immediately contact a service station to check the integrity of the connection.
Oil leak - you can find small oil droplets in the locations of bearings and seals.
Creaks - they can appear when you press the gas pedal. In most cases, squeaks can be associated with faulty hinges. With the appearance of corrosion, the crosspiece may jam, which leads to bearing damage.
Faulty moving bearing - the problem can be identified by a characteristic rustling sound in the area of the moving part of the shaft. During normal operation, the mechanism should not make any sounds, all movements should be smooth. If you hear a rustling noise, the bearing is most likely failing. The problem can only be solved by completely replacing the faulty part.

In rare cases where mechanical damage to the main shaft occurs, severe vibration can be generated due to its incorrect geometry. Some craftsmen recommend manually correcting the geometry of the pipe, but this is the wrong decision and can lead to rapid wear of the entire structure. The best solution would be to completely replace the damaged elements.

Operating principle of HF

The principle of operation of the cardan transmission is the ability to transport torque when the position of the “cardan” in space changes. This principle is implemented through two mechanisms:

Sliding fork of the cardan shaft;
Cross joint.

A sliding fork is necessary to slightly increase the length of the mechanism when driving on uneven roads. Due to the long spline connection, the supply of torque does not stop when the suspension, together with the rear axle, moves up or down.

The hinge, in turn, ensures rotation of the wheels when the bending angle of the CV changes. It is believed that the mechanism is capable of working productively at angles of no more than 20°. Then its active wear begins.

Frequent malfunctions and their elimination

All malfunctions can be divided according to emerging signs of failure:

Vibration when moving - the bearings of the cross or the sliding sleeve are worn out, the balancing of the shaft is disrupted;
Knocks when starting - the sliding joint splines are worn out, the fastening bolts are loose;
Oil leakage from the bearings means wear of the seals.

To eliminate the problems described above, the “cardans” are dismantled and defective, and faulty parts are replaced. If there is an imbalance, the shaft must be balanced under dynamic conditions.

Prospects for the development of a cardan transmission system

The classic ShNUS has some technological disadvantages. The rotation speed of its shafts changes during movement. In this case, the driven shaft can accelerate and decelerate at a stable speed of the drive shaft. This leads to accelerated wear of the mechanism and also creates excess load on the rear axle. Also, the operation of the hinge is accompanied by vibration.

The purpose of the cardan drive can be performed by a shaft equipped with CV joints (front and rear). Similar systems are already used on some SUVs today. Also, the cardan transmission of the VAZ-2107 and other “classics” can be equipped with a CV joint. Repair kits are available for sale.

The use of a constant velocity joint eliminates the disadvantages inherent in the classic cross. The shaft rotation speed is leveled out, vibration disappears, the HF does not require balancing after repair, and the torque transmission angle increases to 17°.

ADVANTAGES

The advantages of cardan transmission include:

Work with significant torques.
Possibility of connecting transmission units installed at large distances from each other.
Implementation of all-wheel drive on a car.
Simplicity of design.
Resistance to loads.

But at the same time, the cardan increases the metal consumption of the transmission and requires significant space for installation, which affects the usable volume of the cabin.

Cardans with unequal velocity joints do not require maintenance and at the same time have a significant service life. Despite the use of bearings in the design, there is no need to lubricate them during operation, since the joint itself is maintenance-free, and the lubricant supplied by the manufacturer is enough for the entire service life.

The cardan is a non-repairable unit. When bent, the cardan requires complete replacement. This is due to the fact that the unit is balanced during manufacturing. Bends lead to imbalance, which increases vibrations and loads in the gearbox and final drive and accelerates wear of the joints.

The hinges are also not repairable, therefore, if increased vibration appears from the cardan side, or third-party sounds (crunches, clicks), the components of the hinge are replaced. Usually the crosspiece and its bearings are subject to replacement, but if the lugs are very worn out, the assembly assembly is replaced.

Cardan transmission - purpose, types of gears, design and operation

As the car begins to move, it forces all its components and assemblies to move, including its transmission. Since it is in constant motion, the relative location of its individual parts may change accordingly.

Uneven road surfaces cause vibration of the drive axles connected by the suspension. The frame and body of the car also undergo some movements as a result of the influence of external factors. Accordingly, they can shift relative to each other and the axis of the shafts of the units that transmit torque from the car engine to the drive wheels.

This system of units is called a cardan transmission and is designed to balance the oscillatory movements of the car’s mechanisms for the smooth transmission of torque.

Depending on the vehicle, the cardan transmission can connect the following mechanisms:

gearbox and transfer case;
gearbox and final drive of the drive axle;
main gears of the rear and middle driving axles;
axle shafts and front drive wheels;
main gear and drive wheels.

The structure of cardan drives in different cars is the same, the only differences are in the size of the units or in the shape of individual elements.

Cardan transmission design

The cardan transmission consists of the following elements:

cardan joints;
main and intermediate shafts;
intermediate support with bearing;
elastic coupling;
connecting mechanisms.

Cardan transmission diagram, GAZ-3302 Gazelle car: 1 - shank of the sliding fork; 2 — sliding fork mud deflector; 3 — sliding fork; 4 — intermediate cardan shaft fork; 5 — intermediate cardan shaft; 6 — mud deflector; 7 — intermediate support; 8 — protective ring; 9 — intermediate support bearing; 10 — protective ring; 11 — splined fork; 12 - U-shaped plate; 13 — lock washer; 14 — crosspiece; 15 — rear propeller shaft fork; 16 — rear propeller shaft; 17 — flange of the main gear drive gear; 18 — rear universal joint; 19 — needle bearing; 20 — retaining ring; 21 - bolt; 22 - sealing ring.

So, let's look at the cardan transmission device

The elastic coupling in this design absorbs sudden jerks and vibration movements.

Diagram of an elastic coupling: 1 - elastic coupling; 2 — flange of the intermediate shaft of the gearbox; 3 — mud reflector; 4 — intermediate shaft of the gearbox; 5 - nut; 6 — centering ring seal; 7 — centering ring; 8 — elastic coupling liners; 9 - bolt; 10 - plug; 11 — front propeller shaft flange; 12 — cuff; 13 — splined end of the front propeller shaft.

Using two flanges, the coupling connects the gearbox and the front driveshaft. These two mechanisms are combined using a centering ring on the gearbox shaft and a centering sleeve, which is located in the driveshaft flange.

note

Cardan shafts are made of steel pipe. The front shaft is equipped with splined ends, and the rear shaft is equipped with universal joint forks.

The intermediate support is a ball bearing that is mounted in a bracket inside a rubber insulating pad.

The cardan joint consists of two forks connected to each other by a cross. The forks themselves are mounted on cardan shafts. On the hollow spikes of the cross there are needle bearings with o-rings.

Types of driveshafts

The main role in the cardan drive is played by the cardan joint, depending on the design of which the following types of cardan drives are distinguished:

transmission with constant velocity joint;
transmission with unequal velocity joint;
transmission with a semi-universal elastic joint;
transmission with a semi-cardan rigid joint.

By the number of shafts, cardan transmissions can be: single-shaft, double-shaft and multi-shaft, and by the number of hinges - single-joint, double-joint and multi-joint.

Operation of cardan gears

A universal joint drive with a constant velocity joint is typically used in front-wheel drive vehicles to connect the transmission to the drive wheels. This mechanism consists of two hinges (external and internal), which are connected by a drive shaft.

Diagram of a constant velocity joint (CV joint): 1 - clamp; 2 - axle shaft; 3 — dirt-proof cover (“boot”); 4 - clamp; 5 - separator; 6 — clip; 7 — semi-minor axis; 8 — hinge body; 9 — retaining ring; 10 - ball; 11 - conical ring; 12 - spring washer.

The constant velocity joint (CV joint) has a spherical body with a cage inside. There are grooves in the holder and body along which metal balls move. The presented design allows for uniform transmission of torque, even despite the changing angle of inclination of the mechanisms.

A cardan transmission with a joint of unequal angular velocities, depending on the distance over which the torque must be transmitted, has one or two cardan shafts. If two shafts are used, the first shaft is called the intermediate shaft, and the second is called the rear propeller shaft. The shafts are connected using an intermediate support, which is attached to the car body.

The unequal velocity joint consists of two forks located at an angle of 90 degrees to each other, a cross and connecting elements (bolts, couplings, flanges). The bearings in which the crosspiece rotates are inserted into special holes in the forks.

The presented cardan transmission differs in that during operation the torque moves unevenly, that is, in one cycle the driven shaft lags behind twice and advances the drive shaft twice, so at least two hinges are used here - one at each end of the shaft.

A cardan transmission with a semi-universal elastic joint ensures the movement of torque between two shafts located at a slight angle relative to each other.

Operation and possible malfunctions of the cardan transmission

Careful operation of the vehicle allows the driveshaft joints and ball joints of the front shafts to maintain their functionality for a long time, at least up to 100 thousand runs.

As for pipes, if there are no mechanical damages, they can be used for many years without replacement, otherwise the bent mechanism should simply be replaced with a new one.

You should pay attention to the condition of the hinge covers and replace them if they are damaged in any way, thereby protecting the hinges.

Important

A reduction in the performance of the joints can be caused by sudden acceleration, slipping in mud, incorrect choice of speeds, and long trips on snowy and dirt roads with deep ruts.

You can find out about a driveline transmission malfunction by the appearance of extraneous sounds or jerking of the car when driving. There are several reasons for the loss of performance of the cardan drive, and among them are the following:

wear of cardan joints;
deformation of cardan shafts;
damage or wear of seals;
damage to the protective cover of the hinge;
bearing wear;
weakening of connecting mechanisms.

These faults are very easy to fix by replacing damaged parts or tightening fasteners.

Chapter 6. Driveshafts (page 1)

Chapter 6.

cardan transmissions

1. Purpose of cardan drives

Transmission of torque when the shaft axes do not coincide and their relative position changes can be provided by cardan joints

.
The shafts connecting the universal joints are called driveshafts
.
A mechanism consisting of one or more cardan shafts and cardan joints and designed to transmit torque between units whose axes do not coincide and can change their position is called cardan transmission
. To compensate for changes in the distance between the transmission units and the cardan drive, axially movable splined couplings can be used.

The following requirements apply to cardan transmissions:

— transmission of torque without creating additional loads in the transmission (bending, twisting, vibration, axial);

— the ability to transmit torque while ensuring equality of angular velocities of the drive and driven shafts, regardless of the angle between the connected shafts;

— high efficiency;

— noiselessness.

On long-wheelbase vehicles, the cardan transmission often consists of two shafts: an intermediate and a main shaft (front or rear). This is necessary in cases where the use of a long shaft can lead to dangerous lateral vibrations as a result of the coincidence of its critical angular velocity with the operational one. A short shaft has a higher critical frequency. The intermediate shaft is mounted on an intermediate support.

If the intermediate shaft connects the driven shaft of the gearbox with the main driveshaft (VAZ, ZIL cars), then the intermediate support must have some elasticity. This is necessary for the reason that the car’s power unit (engine, clutch, gearbox), mounted on elastic cushions, has some freedom in both vertical and horizontal planes. For this reason, the intermediate support bearing housing is installed in a bracket with a rubber ring 1, and the bracket is mounted on the frame cross member (Fig. 1 a).

Some cars use intermediate supports with bearings rigidly installed in the body, but in this case the body itself can swing on axles that are connected to a bracket mounted on the frame cross member.

On three-axle vehicles that have an autonomous cardan drive to the intermediate and rear axles, a rigid support is usually installed on the intermediate shaft (Fig. 1- b

Fig.1. Intermediate supports for the cardan shaft:

a – elastic; b – hard.

Cardan joints of unequal angular velocities (asynchronous), having two fixed swing axes, are used in a cardan transmission when the driven shaft is tilted at an angle of no more than 20°.

Some variants of vehicle transmissions with different combinations of driveshaft arrangements of unequal angular velocities are shown in Fig. 2.

Universal joints

differ from simple ones in that in them axial compensation is carried out in the hinge mechanism itself without the use of an additional spline connection (coupling).

Universal joints of equal angular velocities

(synchronous) are used in the drive of driving steered wheels (Fig. 1-
a
and 1-
b
); The angle of inclination of the driven shaft, depending on the design of the hinge, can reach 45°. Some designs of synchronous hinges are made with a compensating device inside the mechanism, that is, they are universal.

Fig.1-a. Front wheel drive:

/ — internal hinge housing; 2 — internal hinge clamp; 3 —

case fastening ring;
4—
front wheel drive shaft;
5— protective cover; 6 —
protective cover;
7—thrust ring of the cage; 8
- separator;
9 - clamp; 10—
ball;
11
— clip;
12
— retaining ring of the cage;
13 —
outer hinge housing.

Fig.1-b. Details of the front wheel drive outer joint:

— hinge body;
2
- separator;
3
— clip;
4
- balls.

Fig.2. Car transmission diagrams:

– with one rear driving axle;
b
- with front and rear driving axles;
c
- with two rear driving axles;
d
and
e
– with three driving axles;
e
- four driving axles;
1
– clutch;
2
– gearbox;
3
and
6
– cardan shafts;
4
and
8
– rear drive axles; 5 – front driving axle; 7 – transfer case.

2. Universal joints of unequal angular velocities

A typical universal joint has two yokes and a spider. The forks can sway relative to the spikes of the cross, which makes it possible to transmit torque from one shaft to another if their axes are angularly mismatched.

Fig.3. Kinematics of the cardan joint of unequal angular velocities.

Let's consider two positions of the cardan joint, differing in that in the second case the drive shaft is rotated 900 relative to the original position.

In the position shown in Fig. 3- a

, the instantaneous peripheral speed of point
A
can be expressed in terms of the angular velocities of the drive and driven shafts as follows:

VA
= ω 1 ·r = ω 2 ·r ·cos α
,

where ω1

— angular velocity of the drive shaft;

ω2

— angular velocity of the driven shaft.

Where:

In the position shown in Fig. 3- b

, the instantaneous peripheral speed of point
B
is equal to:

V B
= ω 2 ·r = ω 1 ·r ·cos α
.

Thus:

When the drive shaft is rotated by another 900 angle, the instantaneous angular velocity of the driven shaft will again become equal. Therefore, for ω1

=
const
twice in one revolution the angular velocity of the driven shaft changes in the intervals:

ω1 cos α

<
ω2
< ,

which is illustrated by the graph shown at the bottom of Fig. 2.

Obviously, with constant torque and speed of the drive shaft, the power transmitted to the driven shaft will be constant. This means that pulsations in the angular velocity of the driven shaft will cause a synchronous change in torque, which increases the dynamic load on the transmission parts. Fluctuations in torque will be transmitted to the body in the form of vibrations, worsening the comfort of the car.

Since the presence of an unequal velocity joint in the transmission causes additional dynamic loads and vibrations, it is necessary to minimize the consequences of its use. Uniform rotation of the transmission output shaft can be achieved using two universal joints

unequal angular velocities (Fig. 4).

Fig.4. Schemes of two articulated cardan transmissions.

In this case, the uneven rotational speed generated by the first hinge will be dampened by the second, provided that the following requirements are met:

1) the angles between shafts 1 and 2 and shafts 2 and 3 are equal in absolute value ( γ1 = γ2

);
in this case, the relative arrangement of the shafts is possible as shown in Fig. 3- a
and Fig. 3-
b
;

2) the second hinge is rotated relative to the first by 900; this will lead to a corresponding shift in the phase of the vibrations generated by it, and compensation of vibrations from the first hinge; in other words, the forks of the middle (intermediate) shaft must lie in the same plane;

3) all shafts of the cardan transmission lie in the same plane, and the location of this plane in space is indifferent.

It should be noted that even if these requirements are met, the speed of the driveshaft will pulsate. To reduce it, they strive to reduce the angles between the shafts.

The unequal velocity universal joints used in modern cars are mounted on needle bearings, which must be reliably lubricated.

Previously existing hinge designs provided for the mandatory periodic filling of the crosspiece cavity with liquid (transmission) oil through an oiler, and a valve was used to protect the seals from breakdown when pumping oil. Periodic replenishment of the lubricant was necessary because the oil was not held securely enough by the gland seals. In addition, the presence of the valve did not allow reliably lubricating all bearings and removing used lubricant.

Currently, most cars use universal joints that do not require frequent periodic lubrication during operation. Such joints use a grease lubricant: grease No. 000, LITOL-24 or FIOL-2U, which is held in place by reliable oil seals. The lubricant is placed in cups with needle bearings when assembling the hinge (for example, VAZ cars) or in small recesses in the ends of the crosspiece studs. To remove used lubricant and fill it with new one, the hinge must be dismantled. These joints have no grease fittings or valves.

A number of modern grease-lubricated universal joints retain an oiler or threaded hole, closed by a screw plug, and there is no valve. The injected lubricant fills the cavity of the cross and enters the bearings, and its excess is squeezed out through the rubber gland “flow” seals. The seal consists of a radial seal and a double-lip face seal, which protects the bearing from dust and dirt.

Due to its large volume, this material is placed on several pages: 1

Cardan transmission, universal joints. CV joint - purpose, device

_____________________________________________________________________________________________________________________

Cardan drives are used in many trucks and cars. And if we take into account all kinds of agricultural machinery, then the cardan transmission has found very wide application. As you know, the car suspension has a movable mount, so both the driving and steered wheels of the car have the ability to move relative to the body in a vertical plane. However, the power unit and gearbox have an elastic, but rather rigid attachment to the car body. However, the gearbox and drive wheels are connected to each other. And this connection is carried out through a cardan transmission.

The main purpose of the cardan transmission is to transmit rotation from the power unit through the gearbox to the drive wheels of the machine, which can also be steered.

The cardan drive provides a rigid connection between the wheels and the gearbox output shaft and does not interfere with the operation of the suspension.

In other words, the cardan transmission of the car allows you to transmit torque with variable alignment of the articulated units.

Cardan transmission device

The cardan transmission consists of drive and driven shafts, which are connected by a flexible joint. The flexible articulated joint allows rotation to be transmitted smoothly when the angle between the two shafts changes slightly. Based on the type of articulated joint, there are two types of cardan drives:

outdated unequal velocity joints;
more modern constant velocity joints.

A cardan transmission based on unequal velocity joints is most often used to connect the output shaft and the drive axle in rear-wheel drive cars and trucks.

In addition, such hinges are used to connect transfer cases and other auxiliary equipment. Constant velocity joints, which are more advanced in design, are used in modern front- and all-wheel drive vehicles.

Through such cardan drives, the drive wheels of the vehicle are connected to the differential of the drive axle.

Hinge of unequal angular velocities

The cardan transmission with unequal angular velocity joints has the following design elements:

driving, driven and intermediate cardan shafts;
crosses (hinges);
suspended and intermediate supports.

The hinge itself consists of two so-called forks located on the shafts and a cross - the connecting element of the forks. When assembled, the shaft forks are located at an angle of 90° relative to each other and are connected by a cross, which has four cups with needle bearings at the ends.

The presence of needle bearings ensures normal functioning of the hinge at different shaft deflection angles. However, the largest angle between the shafts for a unequal velocity joint is usually no more than 20°.

During assembly, the bearings are filled with grease, which is designed for their entire service life.

If we consider, for example, the cardan transmission of a rear-wheel drive VAZ car, then its design has two hinges, an intermediate shaft and a suspension support for the intermediate shaft.

Due to its, so to speak, imperfect design, the unequal velocity joint does not have the constructive ability to ensure constant (at a constant speed) rotation of the driven shaft relative to the drive shaft.

During one revolution of the hinge, the driven shaft is twice delayed and twice overtakes the drive shaft. In addition, it is worth considering that the unevenness of rotation directly depends on the angle between the shafts; the larger it is, the more pronounced the unevenness is.

However, to eliminate this drawback, a second similar hinge and an intermediate shaft with support are installed. The second joint compensates and equalizes the speeds of both shafts.

4.7. Cardan drives and constant velocity joints

The cardan transmission is designed to transmit torque between the shafts of transmission units located at constant or variable angles relative to each other.

This position of the shafts is due to both manufacturing errors and design features of the vehicle. For example, the driving rear axle of a car is sprung, and the position of its input shaft constantly changes while driving relative to the gearbox output shaft. In some cases, the shafts of the units are in different planes due to inaccurate installation. During the operation of the vehicle, deformation of its frame also occurs and, as a result, the alignment of the shafts of the units mounted on it is disrupted.

The cardan transmission consists of three main elements: universal joints, cardan shafts and their supports.

The basic requirements that the cardan drive must satisfy are the following:

• synchronism of angular velocities connected by shaft transmission;

• high efficiency;

• good balance of cardan transmission parts;

• quiet operation;

• simplicity and reliability of design.

Depending on the number of cardan joints, cardan drives are most often one-, two- and three-joint.

The most widely used is a double-joint cardan drive , consisting of two cardan joints and a cardan shaft connecting them. With a significant distance between the units, they are connected by a three-joint cardan transmission with an intermediate support , and with a short distance, if the mechanisms are located on the same base, for example, on a car frame, with a single-joint drive .

Based on kinematic characteristics, hinges of unequal (asynchronous) and equal (synchronous) angular velocities are distinguished.

The universal joint of unequal angular velocities (Fig. 4.20, a) includes a driving fork 2 and a driven fork 4, which are pivotally connected to each other by a cross 3. The driving fork is rigidly connected to the drive shaft 1, and the driven fork is rigidly connected to the driven shaft 6 or with the help of movable spline connection 5 to change its length. The torque from the drive shaft 1 to the driven shaft 6, the axes of which are located at an angle γ to one another, is transmitted by the hinge as a result of rotation of the driven fork 4 relative to the axis BB, and the cross relative to the axis AA of the drive fork 2. The driven shaft rotates unevenly in relation to to the drive shaft.

Rice. 4.20. Cardan transmission with unequal velocity joints:

a - kinematic diagram of the cardan joint; 6 — cardan transmission diagram; 1.6 - drive and driven shafts; 2, 4 - driving and driven forks; 3 — cross; 5 - spline connection; 7 — gearbox; 8 — final universal joint of unequal angular velocities; 9, 12— intermediate and main cardan shafts; 10 - intermediate support; 11 — intermediate universal joint of unequal angular velocities; 13 — main gear of the drive axle; 14 — main gear drive shaft; α, ß - angles of rotation of the drive and driven shafts of the hinge during their rotation; γ, γ1, γ2 - angles between the shafts; AA, BB - cross axes

The relationship between the rotation angles α of the driving and ß driven shafts during their rotation can be expressed by the following formula tgα-tgßcosγ,

where α is the angle of rotation of the drive shaft during rotation, ß is the angle of rotation of the driven shaft during rotation, …°; γ is the angle between the shafts, …°.

It follows from the formula that the uneven rotation of the driven shaft relative to the drive shaft depends on the value of cos γ. The greater the angle γ between the shafts, the greater the unevenness. Therefore, such a hinge is called asynchronous, or a hinge of unequal angular velocities.

Uneven rotation of the cardan transmission is eliminated by installing a second hinge.

Cardan transmissions with unequal angular velocity joints of the rear drive axle drive transmit torque from gearbox 7 (Fig. 4.20, b) to the drive shaft 14 of the main gear 13, located in the drive axle housing of the vehicle. This transmission consists of a main 12 and an intermediate 9 cardan shafts, an intermediate support 10, two end cardan joints 8 unequal angular velocities and an intermediate cardan joint 11 unequal angular velocities. The intermediate cardan joint 11 is connected to the main cardan shaft 12 using splines. The main driveshaft has two cardan joints, which ensures uniform rotation of the drive shaft 14 of the main gear.

Uniform rotation of the drive shaft 14 of the main gear is possible under the following conditions: the angles between the intermediate cardan shafts 9 and the main drive 12, as well as between the main drive shaft 12 and the drive shaft 14 of the main gear are equal to each other, i.e. γ1 = γ2; the hinge forks connected to the main driveshaft 12 are in the same plane; shafts 9, 12 and 14 are also in the same plane.

If the specified conditions are met, the uneven angular movements of the hinges installed at the beginning and end of the main cardan shaft 12 are mutually compensated, and this cardan transmission as a whole is synchronous, i.e. is a cardan transmission of equal angular velocities. A cardan transmission with two joints can be used at angles between the shafts of no more than 20...30°.

During rotation, due to the uneven distribution of mass over the cross-section of the cardan shaft, a centrifugal force appears, bending it in the transverse plane and causing transverse vibrations of the shaft. This creates additional loads on the cardan transmission parts and reduces the service life. To increase transmission reliability, the cardan shaft is made from a thin-walled pipe of large diameter and made as short as possible.

The cardan transmission of the car, made according to the considered scheme, is shown in Fig. 4.21. This design includes front, intermediate and rear universal joints, intermediate 3 and main 10 cardan shafts and an intermediate support bracket 17 with bearing 18. The intermediate unequal velocity universal joint consists of a shaft 20, made integral with the drive fork 9, a driven fork 8 and the crosspiece 14 connecting them. The shaft 20 is connected to the intermediate cardan shaft 3 using splines 19. The spline connection makes it possible to change the length of the cardan transmission during its operation. Between the axles of the crosspieces and the axes of the forks, needle bearings are installed, the cups 13 of which are held against axial displacement and rotation by the covers 15, which fit with projections into the end grooves of the cups. The leakage of lubricant from the needle bearings is prevented by rubber cuffs 16, and from the spline joint by rubber rings 5 and a felt seal 6. The spline joint is protected from dirt penetration by a rubberized cover 7. Lubricant is pumped to the needle bearings through grease nipples. The spline connection is lubricated when assembling the cardan transmission.

Rice. 4.21. Cardan transmission of the car:

1, 2 - driving and driven forks of the front universal joint; 3 — intermediate cardan shaft; 4 — rubber cushion of the intermediate support; 5— rubber ring; 6 — felt seal; 7— rubberized cover; 8.9— driven and driven forks of the intermediate universal joint; 10 — main driveshaft; 11,12 — driving and driven forks of the rear universal joint; 13 - glass; 14 — crosspiece; 15 - cover; 16 — rubber cuff; 17 — intermediate support bracket; 18 — intermediate support bearing; 19— splines; 20—shaft of the drive fork of the intermediate cardan joint; 21 — balancing plates; IP - bearing needles

The intermediate 3 and main 10 cardan shafts are made of thin-walled pipes. At the front, the driven fork 2 of the front cardan joint is welded to the intermediate driveshaft 3, and the drive fork 1 of this joint is connected to the flange of the secondary shaft of the gearbox. The driven fork 8 of the intermediate joint and the drive fork 11 of the rear universal joint are mounted on the main propeller shaft 10. The driven fork 12 of the rear joint is connected to the flange of the drive shaft of the main gear. After manufacturing, the cardan shafts are balanced by means of welded balancing plates 21. The rear end of the intermediate cardan shaft 3 rests on an intermediate support bolted to the cross member of the car frame. The support consists of an intermediate support bracket 17 and a bearing 18 located in a rubber cushion 4, which dampens vibrations and reduces the load on the intermediate shaft. Loads can be caused by inaccurate installation and frame deformations.

Constant velocity joints (CV joints) are designed as ball, cam and double. These joints are usually used in the drive of steering wheels.

The most widely used is the constant velocity ball joint with pitch grooves , shown in Fig. 4.22, a.

Forks 1 and 5 in this hinge each have four dividing grooves 2 and 4, the middle lines of which are circles with identical radii and centers O1 and O2, equidistant from the center of the hinge O. When assembling the hinge, the grooves of the forks located at right angles are filled with four working balls 3. First, a centering ball 6 is installed between the forks on a pin 7, which fits into the holes of the centering ball 6 and one of the forks. There are ball joints in which the centering ball is installed without a pin.

Rice. 4.22. Constant velocity ball joint with pitch grooves:

a — hinge device; b - operating principle; 1.5—forks; 2.4 - dividing grooves; 3 - ball; 6 — centering ball; 7 - pin; O - center of the hinge; O1 - center of the circle of the center line of the pitch groove 2; O2 is the center of the circle of the center line of the pitch groove 4; AA - bisector plane

The principle of operation of the hinge (Fig. 4.22, b) is that when transmitting torque at an angle, the working balls of the hinges are located in the bisector plane AA, dividing the angle between the shafts in half, which ensures uniform rotation of the driven shaft.

Since the working balls 3 are located symmetrically relative to the center of the hinge, when transmitting torque at an angle, their centers describe circles in the bisector plane AA, while only two balls participate in the transmission of torque. The hinge can transmit torque at an angle of up to 40°.

The advantages of the ball joint include greater efficiency than other joints, which increases its service life. At the same time, they are more complex and expensive.

The cam joint of equal angular velocities (Fig. 4.23) consists of forks 2 and 6 connected to the outer 1 and inner 7 axle shafts. Two semi-cylindrical cams 3 and 5 are inserted into the forks 2 and 6, into the grooves of which disk 4, which is the central link of the hinge, enters. The movement of the shafts during rotation occurs relative to the cylindrical surfaces of the semi-cylindrical fists 3 and 5 and the cylindrical surface of the disk 4. The axes of the fists and the disk are mutually perpendicular. The cam joint is simpler and cheaper than ball joints, but its efficiency is lower.

Rice. 4.23. Cam joint of equal angular velocities: 1.7 - outer and inner axle shafts; 2, 6—forks; 3, 5 — semi-cylindrical fists; 4 - disk

In the drive to the driving steered wheels, double synchronous universal joints are sometimes used - two universal joints of unequal angular velocities, made as a single unit.

Cardan shaft device

The main elements of the most popular modification of the device:

Central shaft (cardan tube, axle). Hollow metal pipe. Solid drawn part. A structural element onto which other parts are attached.
Cross. Important for implementing the function of controlling variable tilt angles and, accordingly, rotating elements. The correct range of variable tilt angles is from 0 to 20 degrees. This is important so that the shaft does not interrupt rotation. High-quality crosspieces are made of alloy steel by hot stamping.
Welded fork. Connecting element between the intermediate and main shaft. Plays the role of a compensator for the height distance between the shafts. The value of a welded fork is especially easy to appreciate off-road. When selecting a fork for a HF (for example, in case of replacement), it is important to take into account the size of the cross, the mounting diameter of the pipe, the maximum hinge angle and the type of fastening.
Hinge fork flange (cardan flange). The fork flange is mounted in the area where the shaft is attached to the bridge. It consists of a flange (flat disk) and two horns in which holes are made for the crosspiece for bolts. The fork is attached to a mating flange on the drive axles or gearbox. The most promising are fork flanges with 4 splined “heels” in the bolt installation areas and splines on the mating flanges. Such solutions are a guarantee of high-quality connection of nodes. When choosing a flange when replacing a part, it is important to take into account the diameter of the holes and their number, and the diameter of the flange itself.
Spline connection. Responsible for the transformation of working length during movement. One spline connection point is fixed on the gearbox, the other on the gearbox. When the vehicle is forced to overcome bumps and holes, the interval between the support points increases, and thanks to the spline connection the cardan “stretches”.

Both forks, the cross and the spline joint form the so-called hinge unit. Its main task is to transmit torque with a changing angle. Exception! On some SUVs, instead of a crosspiece, you can find cardans with CV joints. In this case, there is no spline connection. The device of the KV series includes an elastic coupling. It helps smooth out torque fluctuations and compensate for axial and angular deviations.

Bearings

If we are talking not only about the cardan shaft, but also the cardan transmission as a whole, when considering the device, we must not forget about the bearings. To maintain the propeller shaft in a technically correct position, a suspended metal bearing with a metal cage and a rubber cushion is installed on it. It is the suspended bearing that takes on the load (axial, radial) and ensures rotation and rolling. This is one of the most loaded elements of the transmission, and therefore requires regular maintenance. The intermediate bearing performs the function of supporting the main shaft, providing it with the ability to rotate in the required direction. Bearings in the form of a ring made of elastomer have the best damping properties.

What is the function of the driveshaft?

HF is capable of performing two important functions.

Basic. Transmission of torque from the gearbox or transfer case of the car to the rear wheels. The cardan allows you to gently transfer torque from the transmission to the wheels, dampen vibration off-road, and ensure smooth driving.
Additional. Plays the role of a link between the steering column and the rack. That is, it is already part of the steering mechanism. HF helps improve steering feel.

Thanks to the HF vehicle, good acceleration is ensured even on uneven roads. KV is actually an optimizer of effective unloading of the front wheels and a tool for reducing the risk of slipping.

Drive shaft maintenance

The traditional maintenance scheme is based on three operations:

Checking the condition of the shaft.
Replacing faulty parts (precisely replacement, restoration in the presence of backlashes and cracks is an illiterate solution to the problem).
Spline joint lubrication. When selecting a lubricant, pay attention to the welding load (responsible for extreme pressure properties). Expensive products are oriented towards welding loads up to 3920 Newtons. For HF splines on heavy freight vehicles, their use is only encouraged. For passenger cars, lubricant for low-load splines is sufficient. Overpaying for the product is not advisable here.

On some cars, the bearings of the KV crosspieces also need to be lubricated. But there are not very many vehicles that require such a procedure. These are HF vehicles with a grease fitting.

Features of operation

The main feature, which is also a disadvantage of this hinge, is the uneven cyclic transmission of rotation. That is, due to the existing angle between the shafts, the driven part of the drive alternately either overtakes or lags behind the driving part. Because of this feature, the hinge is called “unequal angular velocities”. Therefore, in front-wheel drive, shafts with such a device are not used.

The peculiarity of the operating principle of the cardan transmission is taken into account by the design. To partially compensate for uneven transmission, the drive device uses two or more hinges simultaneously. You can also often find a semi-cardan elastic element on passenger cars.

In order for the existing cardans to compensate for cyclic uneven transmission, they still need to be correctly positioned relative to each other. To do this, the hinges are placed synchronously, and not offset from each other. That is, the internal forks mounted on the tubular shaft and the external ones connected by flanges to the axes of the units are installed in the same plane.

The semi-cardan elastic element is structurally very similar to the unequal velocity joint. It also has two forks, but they are connected into a single structure using an elastic (rubber) insert. There are also designs with a flange connection.

Despite their disadvantage, cardans are widely used. And this is facilitated by the high reliability of the hinge and unpretentiousness to working conditions. This allows the driveline to be left open, without any protective elements.

In general, the cardan drive can operate for a very long time without any maintenance. Failure of the hinge can only be caused by contaminants entering the bearings due to damaged seals. And even then, this will not immediately lead to breakdown. The cardan will become unusable only if the needle rolling elements of the bearings are significantly worn. The hinge itself is irreparable and when worn out it is simply replaced.

OPERATING FEATURES OF THE CARDAN TRANSMISSION

A feature of this hinge is uneven rotation. When the angle of position of the drive shaft relative to the driven one changes, the latter accelerates or slows down at certain points, that is, the angular velocity increases or decreases. Moreover, as the angle increases, the speed of advance or lag of the driven shaft from the drive shaft increases, so this transmission of rotation is cyclic in nature. A significant angle (more than 20 degrees) between the shafts increases the load on the hinge components, which can lead to failure.

Let's look at the principle of operation of a cardan joint using an example when the drive shaft is positioned strictly horizontally, and the driven shaft is positioned at an angle downwards (standard position of the cardan joint). The initial position of the inner hinge fork is also horizontal. When transmitting rotation due to the angled position, the downward portion of the fork accelerates relative to the drive shaft. Maximum advance is achieved at the bottom point.

At the same time, part of the driven shaft fork, which began to move upward during rotation, slows down and lags behind the driving one in rotation speed. The maximum lag is at the highest point.

Due to these features of the operation of the joint of unequal angular velocities, rotation is transmitted unevenly.

To reduce the unevenness of rotation speeds and loads, the design of the cardan transmission uses two hinges - at the ends of the hollow shaft. Moreover, for maximum smoothing, the internal forks are located in the same plane.

Due to the use of two hinges, the position angles of the shafts and, accordingly, the unevenness of rotation speeds are reduced.

Due to the uneven rotation between the shafts, the cardan transmission is not used in the transmission design of front-wheel drive vehicles. On such models, the unequal velocity joint is replaced by a constant velocity joint, in which transmission is carried out evenly regardless of the angle between the shafts.

Kinds

Several types of these hinges are used in vehicles:

Equal angular velocities
Unequal
Elastic semi-cardan

The first option is CV joints, used only on vehicles with rotation transmission to the front wheels.

As for rear-wheel drive and all-wheel drive models, all of the listed types can be installed simultaneously in their design. For example, on conventional cars with a drive, one unequal velocity joint and one semi-cardan joint are installed on the rear axle. But on crossovers with all drive wheels and with a transverse engine position, there are all types of joints - CV joints are used at the front, and two other types are used at the rear.

Cardan transmissions are classified according to three criteria:

by the number of shafts (single-shaft, double-shaft, multi-shaft);
by the number of hinges (single-hinged, double-hinged, multi-hinged);
by type of joints (with joints of equal/unequal angular velocities).

Products with different angular velocities are used in the designs of rear-wheel drive vehicles, as well as in all-wheel drive vehicles. The hinge consists of two forks that are located on shafts. The forks are connected to each other using a cross.

Cardan transmission device

outdated unequal velocity joints;
more modern constant velocity joints.

A cardan transmission based on unequal velocity joints is most often used to connect the output shaft and the drive axle in rear-wheel drive cars and trucks. In addition, such hinges are used to connect transfer cases and other auxiliary equipment. Constant velocity joints, which are more advanced in design, are used in modern front- and all-wheel drive vehicles. Through such cardan drives, the drive wheels of the vehicle are connected to the differential of the drive axle.

Requirements for cardan drives

The basic requirements for cardan drives are as follows:

transmission of torque at all possible operational values of angular velocities and angles y between the shaft axes;
high efficiency even at significant angles;
minimal vibration and noise;
absence of significant axial forces and wear in the compensating connection.

In addition, cardan transmissions, like other vehicle mechanisms, are also subject to general requirements:

ensuring minimum dimensions and weight
high reliability
minimal maintenance
manufacturability

Let's consider what design measures ensure compliance with the requirements for cardan drives.

High efficiency of cardan drives with unequal velocity joints is ensured by the use of needle bearings in the joints with reliable lubrication and reliable sealing at bend angles within y = 5... 10°. To reduce the fracture angle to the specified values, sometimes the engine or rear axle is positioned with an inclination angle of 2...4°. At fracture angles less than 3...5°, the needles have a bridging effect on the spikes of the cross (dents form under the needles). Therefore, at very small fracture angles, bronze bushings must be used instead of needle bearings. Brinsillironanis can also occur when there is a large gap between the needles, when the needles become distorted and create high pressure on the spider tenon. Therefore, the total inter-needle gap should be less than half the needle diameter.

The high efficiency of cardan drives with constant velocity joints is ensured mainly by the use of relatively large balls in these joints, which roll in grooves of a special profile. The sometimes used double u-joint with needle bearings usually shows significant wear on the bearings and the spider studs. This occurs because the bearing needles do not roll when moving in a straight line. Cam universal joints used on heavy-duty vehicles have lower efficiency compared to other constant-velocity joints, since sliding friction is used between their parts at fracture angles that are not equal to zero. However, even in ball joints, the middle parts of the grooves wear out the most, which corresponds to linear motion.

Minimal vibration and noise when using unequal velocity joints is ensured by reducing the length of the driveshaft, for example, using a three-joint driveshaft with an intermediate support, increasing the diameter of the driveshaft, reducing the bend angle, reducing clearances in the bearings, and installing an elastic joint in the driveshaft. However, the cardan shaft located after the first unequal velocity universal joint is a source of torsional vibrations.

When using constant velocity joints, the accuracy of the alignment of the center of the joint with the axis of the pivot is of great importance.

The absence of significant axial forces and wear in the compensating joint when using unequal angular velocity joints is usually ensured by the use of a spline joint with a slightly increased lateral clearance and a spline length equal to about two diameters of their shaft, with reliable lubrication and sealing. There have been attempts to replace sliding friction in a spline joint with rolling friction by placing rollers on the side surfaces of the splines. However, this design has not become widespread.

When using some constant velocity joints in the drive of the front drive wheels of passenger cars, one of the two joints is made universal, performing the functions of both a hinge and a compensating device. In this case, balls or rollers, moving in longitudinal grooves, allow the cup to move in the axial direction relative to the internal sprocket.

Cardan transmission with semi-cardan elastic joint

The semi-cardan elastic joint ensures the transmission of torque between two shafts located at a slight angle due to the deformation of the elastic link.

A typical example of this type of articulated joint is the Guibo elastic coupling. The coupling is a pre-compressed hexagonal elastic element, on both sides of which the flanges of the drive and driven shafts are attached.

The cardan transmission is designed to transmit torque between shafts located at an angle to each other. In a car, cardan drives are usually used in the transmission and steering.

The following transmission elements can be connected using a cardan drive:

engine and gearbox;
gearbox and transfer case;
gearbox and final drive;
transfer case and final drive;
differential and drive wheels.

The main element of the cardan transmission is the universal joint. Depending on the design of the joint, the following types of cardan drives are distinguished: with a joint of unequal angular velocities, with a joint of equal angular velocities, with a semi-cardan elastic joint, with a semi-cardan rigid joint.

A cardan transmission with a semi-cardan rigid joint is not used on cars, because does not meet the requirements of reliability and manufacturability.

Cardan transmission with unequal velocity joint

A cardan transmission with a joint of unequal angular velocities has a well-established name - cardan transmission, the common name is cardan. This type of transmission is mainly used on rear-wheel drive vehicles and vehicles with all-wheel drive.

The cardan transmission includes unequal velocity joints located on the cardan shafts. If necessary, an intermediate support is used. Connecting devices are installed at the ends of the cardan transmission.

The unequal velocity joint combines two forks located at an angle of 90° to each other, a crosspiece and locking elements. The crosspiece rotates in needle bearings mounted in the fork lugs. The bearings are maintenance-free; grease is added to them during assembly and does not change during operation.

A feature of the unequal velocity joint is the uneven (cyclic) transmission of torque, i.e. in one revolution, the driven shaft lags behind twice and overtakes the driving shaft twice. To compensate for uneven rotation in the cardan transmission, at least two hinges are used, one on each side of the cardan shaft. In this case, the forks of opposite hinges are located in the same plane.

In a cardan transmission, depending on the distance over which the torque is transmitted, one or two cardan shafts are used. With a two-shaft design, the first shaft is called the intermediate shaft, the second - the rear propeller shaft. The joint between the shafts is fixed using an intermediate support. The intermediate support is attached to the car body (frame). To compensate for changes in the length of the cardan transmission that occur as a result of operation, a splined connection is made in one of the shafts.

The connection of the cardan drive with other transmission elements is made using connecting elements: flanges, couplings, etc.

Cardan transmission with constant velocity joint

A cardan transmission with a constant velocity joint is widely used in front-wheel drive vehicles to connect the differential and the drive wheel hub.

This type of cardan transmission includes two constant velocity joints connected by a drive shaft. The joint closest to the gearbox (differential) is called the internal joint, the opposite one is called the external joint.

In order to reduce noise levels, a cardan drive with a constant velocity joint is also used in transmissions of vehicles with rear-wheel drive and all-wheel drive. In this case, the unequal velocity joint is inferior to the more advanced CV joint design.

The constant velocity universal joint ensures the transmission of torque from the drive to the driven shaft at a constant angular speed, regardless of the angle of inclination of the shafts. The most common type of transmission design for a front-wheel drive vehicle is a constant velocity ball joint.

A constant velocity joint (abbreviated name - CV joint, common name - grenade) is a cage placed in a housing, between which the balls move.

The body has an internal spherical shape. There is a clip inside the case. The body and holder have grooves along which the balls move. This design ensures uniform transmission of torque from the driven shaft to the drive shaft at a varying angle. The separator holds the balls in a certain position. To protect the hinge from negative environmental factors (oxygen, water, dirt), a dirt-proof cover – “boot” – is installed on the CV joint.

During manufacturing, a lubricant prepared on the basis of molybdenum disulfide is placed in the constant velocity joint.

Cardan transmission with semi-cardan elastic joint

The semi-cardan elastic joint ensures the transmission of torque between two shafts located at a slight angle due to the deformation of the elastic link.