Viscous coupling - what is it, how does it work?
Machine operation

Viscous coupling - what is it, how does it work?

Design and application of viscous coupling

The viscous clutch is an automatic clutch with a simple structure and a wide range of applications. Inside the body of such a clutch, two sets of discs are alternately located. One block is enclosed in a housing, and the other is mounted on a connecting shaft. The discs may move slightly in the axial direction. The entire viscous coupling is sealed and filled with engine oil or kinetic fluid. It can be placed in the vehicle's cooling system or between the gearbox output shaft and driven axle., for example, in front of the rear axle, in the case of transfer of driving force between the axles of the vehicle.

How does a viscous coupling work? 

The viscous coupling works on a purely mechanical basis. The moment of engagement and disengagement of the clutch coincides with the moment when the liquid in it, under the influence of temperature, slowly seizes the clutch elements on the shaft leading from the engine. At this moment, the fan installed on the viscous coupling starts to rotate.

The use and symptoms of a viscous coupling in the cooling system

Viscous coupling - what is it, how does it work?

Every internal combustion engine in a car needs lubrication and proper cooling. It doesn't matter if it runs on petrol, diesel or LPG. The refrigeration system and the liquid circulating in it are responsible for cooling. After heating, it is redirected to the radiator. In normal driving, the circulation of fluid in the radiator, cooled by the air pressure in your car, is sufficient.

Viscose is used in the transmission and engine cooling system. This is very important when driving in conditions that can cause the engine to overheat. When you are driving in traffic jams around the city, for short distances or it is hot outside, the radiator is not enough to cool the liquid. To eliminate the risk of overheating of the drive unit, the fan is started, which is usually controlled by a viscous coupling. A large amount of air is blown through the radiator.

Visco coupling in all-wheel drive vehicles

Automotive manufacturers have been installing viscous couplings for many years. They are responsible for the distribution of driving force between the rear and front axles, for example, in SUVs or crossovers, which eliminates the need for other expensive mechanisms. Due to its viscosity, viscous coupling is then also called viscous or viscose. In 4x4 drive systems, the viscous coupling turns on the drive of one of the axles, usually the rear, in the event of wheel slip.

Viscous coupling damage symptoms

In the traction transmission system, the most obvious sign of a viscous coupling failure will be the loud operation of the entire mechanism - a characteristic rattling. You may also notice the lack of XNUMXWD disengagement when you drive the car in perfect traction. In this case, the problem with the viscous coupling may be due to insufficient oil in the clutch or mechanical damage to this part of the car.

What are other warning signs of a malfunction? Symptoms of damage to the viscous coupling can be unambiguous. A fault message will appear on the trip computer screen along with an engine and system check icon. If the problem is the system overheating, just wait a few minutes. The temperature will drop, the system will cool down and the viscous coupling will work properly.

It is worth checking the condition of the viscous coupling on an ongoing basis, during each visit to the service. If there are clear and visible signs of mechanical damage or leaks, check the condition of this part of the car.

How to check the viscous fan clutch? 

It happens that with constant jamming of the clutch, the radiator fan still works. However, this occurs when the engine is started, and not when the system overheats. In this case, you need to quickly diagnose the problem, because the water pump and the entire timing system are under heavy load.

In the reverse situation, the viscous coupling may not turn on at all, so the fan will not cool the liquid in the radiator. You'll pick it up from the higher and ever-increasing engine temperature.

Is regeneration of the viscous coupling beneficial?

If the mechanic thinks that this part of the car is damaged, you can decide if it can be repaired or you will have to buy a new viscous coupling. Regeneration of a viscous coupling will, of course, entail less cost than buying a new part. Usually its cost ranges from 3-8 thousand. zł, depending on the stage of system promotion.

In practice, there is no way to repair a broken viscous coupling. Its damage is usually associated with the need to replace this element with a new one. It is worth choosing a reliable supplier of viscous couplings, which will ensure the correct storage of parts. Thanks to this, you will be sure that the new clutch will work properly for a long time.

Add a comment