Hydraulic Clutches: Basics, Parts, Working, Applications

Hydraulic clutches are explained along with definition, parts, working process, advantages, disadvantages, etc. Let’s explore the hydraulic clutches!

What are Hydraulic Clutches?

Let’s try to understand what is centrifugal clutch along with basics, definition, etc.

Hydraulic Clutch Basics

Let’s start with the basics of the hydraulic clutch. One of the important aspects of any vehicle is the transmission system.

  • In this transmission system, the clutch is one major part of the assembly.
  • Clutch is responsible for engaging or disengaging the engine power.
  • It acts as a mediator for transferring the engine power.

There are lots of types of clutches used in vehicles. One of them is the hydraulic clutches. The Hydraulic clutches are the one that operates on the fluid power. Let’s dig up some more information on these types of clutches and its details.

Function of Hydraulic Clutch

The hydraulic clutches are selected as an alternative to the mechanical clutches used in the normal vehicles. There are few reasons to use hydraulic clutch.

  • It’s kind of adds up the modern touch for the vehicles.
  • In case of mechanical clutches, there is a steel cable that connects the clutch pedal directly to the clutch assembly. However, in case of hydraulic clutches, the fluid is used instead of the steel wire.
  • The clutch depends on the reservoir cylinders to control the pressures as per relation with the pedal pressed by the driver.
  • Hydraulic clutch falls under the category of the multi-plate clutch.
  • We know the function of the clutch it engages, disengages the clutch plate from the engine. The force from the hydraulic fluid is used to disengage and engage the clutches.

So, to get this working there are various components that incorporates the working of the hydraulic clutches.

Parts of Hydraulic Clutches

Let us learn all the parts of the hydraulic clutch, as follows,

  • Clutch pedal
  • Diaphragm clutch
  • Clutch plate
  • Surface of friction
  • Pressure plate
  • Master cylinder
  • Slave cylinder & pushrod
  • Flywheel
  • Diaphragm springs
  • Splined sleeves

Let’s discuss all these parts one by one!

Hydraulic clutch parts or components

Clutch Pedal

You can call this one as an actuating part of the hydraulic clutch or any clutch.

  • For disengagement of the clutch, you need to push the clutch and the clutch will be applied.
  • When the driver presses the clutch pedal the clutch plate will start the rotation and further operation will start.

Diaphragm clutch

In the hydraulic clutches, the diaphragm clutch is used. Though the diaphragm clutch is an independent clutch type.

Clutch Plate

A thin metal plate is used to make a clutch plate. On both sides of the clutch plates, there is the friction lining present.

  • The clutch plate is one of the important parts of the hydraulic clutch.
  • The location of the clutch plate is between the pressure plate and the flywheel.

As the friction lining is provided on both of the sides clutch plates, one of the sides is connected or makes the contact with the flywheel, and the other lining with a pressure plate that causes the friction.

Surface of Friction

The friction surface is made when the clutch plate friction lining makes contact with the pressure plate and the flywheel. At the time when the clutch plate starts the rotation, due to the contact friction force will be generated.

Pressure plate

The pressure plate is attached or placed at the one side of clutch plate. By using the bolts and springs the pressure plate is attached.

  • As we already know the pressure plate will make contact with the clutch plate friction surface.
  • Basically, the pressure plate depends on the weight, after giving the weight the clutch plate surface will produce friction.

Master Cylinder

Master cylinder, as the name suggests, means the main cylinder where the fluid i.e. clutch fluid, is stored. It is basically piston cylinder arrangement. Once paddle is pressed, a hydraulic pressure is created in the master cylinder and this hydraulic pressure is transferred to the slave cylinder.

Slave Cylinder & Pushrod

This is another cylinder used in the hydraulic clutch, where a separate rod is connected to the clutch fork through a rod called a pushrod. Due to the hydraulic force or power from the main cylinder, clutch fork moves and it helps to release the thrust bearing. It helps further to release the pressure plate and disengage the hydraulic clutch.


The other part which makes contact with the friction surface of the clutch plate is the flywheel. It is connected to the transmission shaft after making contact with the frictional surface it produces friction.

Diaphragm springs

These are attached to the pressure plates. The springs will work with the help of pressure plate by getting the high weight.

  • By getting the high weight and is given to the pressure plate.
  • Due to the thrust spring action, it will make contact with the friction surface and it will produce high friction.

Splined Sleeves

The splined sleeves work is to help the engagement and disengagement of the clutch system such as the hydraulic clutch system.

  • They are placed between the friction lining of the clutch plate and to pressure plate.
  • When the pressure plates give pressure then the sleeves will move forward and will make the clutch engaged.
  • Whereas when the pressure plate releases pressure, the splined sleeves will go back and will make the clutch disengaged.

Now, to understand how does a hydraulic clutch works, the basic idea of a hydraulic system should know. Let’s try to understand the basics of hydraulic systems.

Hydraulic System Basics

The hydraulic system works on Pascal’s lawOpens in a new tab.. It is also known as Pascal’s principle or principle of transmission of fluid pressure.

  • There are some components in this hydraulic system.
  • The fluid used in the hydraulic system is also known as the brake fluid or mineral fluid.
  • It has a reservoir in which the fluid is stored.
  • The clutch master cylinder is connected directly to the clutch pedal so it can act accordingly.
  • The pushing force generated by the user will force the piston and the fluid will be compressed inside the master cylinder.
  • There are pressure pipes that will be used for transferring the pressure.
  • It will transfer the high pressure from the master to the slave cylinder.

Now another part of the hydraulic system known as pushrod will be acting on the clutch fork that will release the pressure plate and open the clutch. Now we know about the components and their brief descriptions. So, what is the working principle of the hydraulic clutches?

Though you may have a brief prediction after knowing the function of components of the hydraulic systems. Would you like to learn the basics of clutch? Click What is Clutch

How Does a Hydraulic Clutch Work?

We know already that the clutch will either engage or disengage the engine power to other components. So, the working is divided into two categories.

Hydraulic Clutch Engagement

  • All the process starts when the driver presses the clutch. It will start the engagement process.
  • After clutch pedal is pressed the diaphragm clutch process will start.
  • As the clutch pedal attached to the clutch plate, clutch will start to rotate.
  • Now the friction surfaces will be making contact with the flywheel as well as the pressure plates.
  • The pressure plate will transfer the pressure to spring and spring will make the contact with splined sleeves.
  • Lastly, the sleeves will be engaging the clutch.

Hydraulic Clutch Disengagement

  • When the driver will release the pedal the disengagement process will start.
  • The splined sleeves which were moved forward for engagement will be coming backwards for disengagement.
  • This will result in loss of contact between the pressure plate and the clutch plate.
  • Now flywheel will be also released from the contact of clutch plate.
  • Clutch plate rotation will slow down and it will be stopped.
  • Hence, the clutch is now disengaged.

Now we have known all the components their working and the working principle of the hydraulic clutches. Let’s check out some of the advantages and disadvantages of the hydraulic clutches.

Advantages of Hydraulic Clutches

There are many advantages of the hydraulic clutch, as follows,

  • The friction in the hydraulic clutches is pretty much less as compared to the mechanical clutches. Hence, they are preferred over mechanical clutches if low friction is required.
  • Hydraulic clutches are self-lubricating ones. They have hydraulic bearing oil, so it’s a self-lubricated clutch.
  • Low maintenance is there for the hydraulic clutches. There is less friction that will be harmful to the parts and also, it’s self-lubricating so it will not require any lubrication maintenance.
  • The pedal height is automatically adjusted in case of hydraulic clutches.
  • The cable in the mechanical clutches may get damaged. But in case of hydraulic clutches, there are no cables so the hydraulic clutch is free from damages because of the cables.
  • The hydraulic clutch systems are safer as they are easy to operate.
  • The reliability of the hydraulic clutches is more as compared to the mechanical clutches.
  • The quality of the hydraulic clutches is better than the mechanical clutches.
  • The variation in hydraulic clutches is more so they can be fitted at any place.

Disadvantages of Hydraulic Clutches

Apart from the advantages, there are few disadvantages as well of the hydraulic clutch. These are,

  • The area required for the hydraulic clutches is large. Because the number of pipes and system of the hydraulic clutches is large hence the area requirement is large.
  • As the number of parts and other considerations, hydraulic clutches are expensive than mechanical clutches.
  • The brake fluid or mineral fluid is also costly this one is the major disadvantage of the hydraulic clutch system.
  • Another major problem is leakage. The hydraulic clutch transfers a large quantity of oil so the leakage is more in case of hydraulic clutches.
  • The piping systems of the hydraulic clutches is consisting of plastic metallic. The pipe can break or teared down. Time-to-time checking is necessary to avoid any major damages.
  • The standard fluid should be maintained in the hydraulic systems. If the correct fluid is not used the seals may get damaged.
  • Time to time checking of the hydraulic fluid is compulsory.

Applications of Hydraulic Clutches

The application of hydraulic clutches are,

  • Hydraulic clutches are widely used in vehicles.
  • Due to their quality and performance, it is adopted by lots of reputed manufacturers.
  • The use of the hydraulic clutch is more in the trucks and automotive industries.
  • The advantages like self-lubrication, variation according to applications, are widely used in lots of applications.

Comparison between Mechanical and Hydraulic Clutches

Let’s see the basic comparison between mechanical clutch and hydraulic clutch,

  • Hydraulic clutches are considered to be modern clutch. Whereas the mechanical clutches are the ones that are old.
  • Easier clutch handling, the smooth operation makes the switching to hydraulic clutches worthwhile. Whereas switching to mechanical clutches might be a little time-consuming to get used to of the clutch.
  • Vintage cable-type feels and the more engagement shots of mechanical clutches make them a choice for some circle of users.

Let’s check out some pros and cons of both clutches so you will get the better idea.

Mechanical Clutches Pros and Cons


  • The vintage feel and experience.
  • It is a simple system compared to the hydraulic systems.
  • The cost is pretty much less as compared to the hydraulic clutches.
  • Feels engaging to drive.
  • Easy repairs and maintenance because of simple systems.


  • The adjustment of peddle is required.
  • The lubrication is required separately because mechanical clutches are not self lubricating.
  • Hydraulic clutches are modern
  • Steel cable used in the mechanical clutches are prone to breakage.

Hydraulic Clutch Pros and Cons


  • Easier pedal press.
  • Smoother operations as compared to the mechanical clutch systems.
  • The adjustment of the pedal is not required as it will adjust itself accordingly.
  • Self-lubrication eliminates the oiling maintenance of the hydraulic clutches as they are self-lubricating.


  • The hydraulic clutches require bleeding.
  • The repairs can be costly as the system is complex as compared to the mechanical clutches.
  • Oil leakage is one of the major problems of hydraulic clutches.
  • They are better in quality than the mechanical clutches.

Specification of Hydraulic Clutch

The details of the below parameters should be part of the specification this type of clutch,

  • Torque Rating
  • Power:
  • Rotational Speed:
  • Maximum Pressure:
  • Clutch Engagement:
  • Spring Assistance:
  • Features & Options:
  • Shaft Configuration:
  • Drive / Load Connection:
  • Bore Diameter:
  • Diameter:
  • Length:
  • Weight:
  • Application / Type:

Manufacturers of Hydraulic Clutch

There are many manufacturers available, as follows,

  • Metro Hydraulic Jack Co.
  • SunSource Addison
  • Francic Klein
  • Ohio Power Tool Columbus,
  • Progressive Power and Control Indianapolis
  • Vortex Engineering Works
  • ZEMARC Corporation
  • Ellco India, etc.


So now you may have an idea about both of the clutches and their respective pros and cons. The hydraulic clutches are mostly used in heavily loaded vehicles. They are much safer and provides smoother operations. These advantages are useful for heavy vehicles.


Hello Everyone! We, Rituparna Guha & Firan Mondal, are delighted to present our Mechanical Engineering articles. We will capture all types of articles and try to explain in the simplest way with a lot of diagrams! Happy Reading....

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