Single Plate and Multi-Plate Clutches: Construction, Operation, and Advantages

What Is a Single Plate Clutch?

The single-plate clutch consists of a clutch plate and operates on the principle of friction. These are of two types: helical spring type and diaphragm spring type.

In helical spring-type clutches, helical springs are used uniformly over the cross-sectional area of the pressure plate to suppress the axial force. In a diaphragm spring type clutch, diaphragm spring is used to exhale axial force.

Construction of Single Plate Clutch:

The various parts of a single plate clutch are arranged in a systematic order for its proper functioning. The most important part of a single plate clutch is the clutch. A plate consisting of a clutch plate with friction lining on both sides.

There are other parts that help in the proper functioning of the clutch, such as flywheels, pressure plates, thrust bearings, hubs, springs, and mechanisms to engage and disengage the clutch.

The clutch plate moves axially in the driven shaft and is connected with the hub between the flywheel and the pressure plate. The single plate for the clutch plate must be in the clutch, the friction lining on either side as it is placed between the flywheel and the pressure plate.

The friction torque in the single-plate clutch is responsible for transmission. The pressure plate is connected with the flywheel and springs. The main function of the pressure plate is to help the clutch plate move towards the flywheel.

A lever with some mechanism on the driven shaft is attached to the thrust bearings, which transmits input and output speeds from the clutch pedal.

Parts of Single Plate Clutch and Their Functions:

Four parts of single plate clutch and their functions:

Clutch Plate.
Pressure Plate.
Springs.
Flywheel.

#1. Clutch Plate

The clutch plate is the main component of the clutch. A single plate clutch has only one clutch plate. It is a thin disk type of metal plate with a frictionless surface on both sides. These abrasive surfaces are called friction lining.

These friction lining must be made of such material that it provides torque transmission without slip. The co-efficiency of friction of materials should be high. The clutch plate is assembled between the flywheel and the pressure plate.

#2. Pressure Plate

The main function of a pressure plate is to maintain proper contact between the flywheel and the clutch plate surfaces via springs. Pressure plates are usually made of cast iron.

#3. Springs

Springs are used to move the flywheel plate toward the flywheel plate and to establish a proper connection between the clutch plate and the flywheel. It also prevents the slipping of contact surfaces.

#4. Flywheel

The flywheel is connected to the engine output. When the clutch is in a busy position, the flywheel comes into contact with the clutch plate, and the torque is transmitted by friction.

Working of Single Plate Clutch:

This is the most common type of clutch used in motor vehicles.
The single-plate clutch has only one clutch plate, which is mounted on the spline of the clutch shaft.
The flywheel is mounted on the engine crankshaft and rotates with it.
The pressure plate is bolted to the flywheel with the help of clutch springs and is free to slide when the clutch pedal is pressed.
When the clutch pedal is not pressed, the clutch is called for engagement, and at that time, the clutch plate catches between the flywheel and the pressure plate.
There is friction lining on either side of the clutch plate. Therefore, when the clutch is engaged, there is friction between the flywheel, the clutch plate, and the pressure plate. So as the clutch plate rotates, the clutch shaft also rotates.
The clutch shaft is connected to the transmission. Thus engine power is transmitted from the crankshaft to the clutch shaft.
When the clutch pedal is pressed, the pressure plate moves back against the force of the springs, and the clutch plate is released between the flywheel and the pressure plates. Therefore, the flywheel continues to rotate until the engine is running, and the clutch shaft speed gradually decreases, and eventually, it stops rotating.

Advantages of Single Plate Clutch:

Here, the different Advantages of single plate clutch are as follows

The single-plate clutch is smooth in operation, i.e., the clag’s engagement and ingestion are smooth.
There is very little slip in its operation. During icing, the clutch only occurs slip, and thereafter, there is no slippery, and functioning becomes very smooth.
Power loss is very low.
Very little heat is produced because only one clutch plate is used.
In this type of clutch, the operation is very fast.

Disadvantages of Single Plate Clutch:

Here, the different Disadvantages of single plate clutch are as follows

Torque transmission capacity is low.
The size of this clutch is also large for low torque transmission.
This is a dry clutch, so it is necessary to protect it from moisture.
Tear wear is more likely in a single plate clutch.

Types of a Single-Plate Clutch:

Two types of single plate clutch:

Helical Spring Type Single Plate Clutch.
Diaphragm Spring Type Single Plate Clutch.

#1. Helical Spring Type Single Plate Clutch-

The figure below represents a single plate clutch of helical spring type. For simplicity, the clutch pedal and other links that cause circulation of the pressure plate are not shown. The clutch plate is mounted on the split shaft and can move along the axis of the shaft.

As far as rotational motion is concerned, there is no relative movement between the plate and the shaft. Both have the same rotational speed due to the splines provided on the shaft. The flywheel is mounted on the crankshaft of the engine and rotates with it.

The pressure plate is carried through the clutch springs to the flywheel. This clutch can slide freely along the axis of the shaft. The clutch is engaged due to the forces exerted by the clutches spring. These forces cause contact between the pressure plate, the clutch plate, and the flywheel.

The clutch plates are located between the flywheel and the pressure plate. The clutch plate is provided with friction material on both sides. Rotary movement from the flywheel is transferred due to friction to the clutch plate and the clutch shaft. The clutch shaft also acts as an output shaft.

To the clutch when the clutch pedal is pressed. Is displaced. The pressure plate moves back against the force of the springs, and the clutch plate is released between the flywheel and the pressure plate.

Thus, the flywheel keeps rotating until the engine runs but the clutch plate speed decreases and becomes zero. In this case, the motion is not transferred to the clutch shaft.

#2. Diaphragm Spring Type Single Plate Clutch-

In this type of clutches, the helical springs are replaced by a single diaphragm spring, which is a saucer-shaped disc. The disk is provided with a profile, as shown in the figure below.

The disc adopts a flat shape when the clutch is fitted. In the decomposed state, the disc adopts the shape of a buck, as shown.

The figures below represent a simplified view of the clutch assembly.

The scene shows the clutch in the ‘engaged’ position. The diaphragm spring exerts a force on the pressure plate, which causes contact between the pressure plate, the clutch plate, and the flywheel.
When the force is applied through the clutch pedal, the diaphragm spring is pressurized, and contact between the pressure plate, clutch plate, and flywheel is lost.
The clutch is aged ‘disengaged,’ and the motion from the flywheel is not transferred to the clutch shaft.

What Is Multi Plate Clutch?

A clutch with more than one powered plate is called a multi-plate clutch. Sometimes, a single clutch plate may not transfer the required speed. This may be due to the low friction force. the friction forces can be increased by increasing the contact area.

This increases the size of the clutch, and due to limited space available, it can be challenging to increase the size. Therefore to increase the area of contacts, the number of clutches plates increases. the anatomical description of the multi-plate clutch is shown in the figure below.

Simplify the shape; the mechanism of attaching and dislocating the clutch is not shown. Internal splines are provided on the flywheel. The clutch shaft is provided with splines. the clutch plates are assembled and pressed firmly with the help of a pressure plate by coil springs.

These coils exert a spring axle force, which causes contact between the clutch plates, the flywheel, and the pressure plate. Friction surfaces on both sides of the plates help to transfer momentum from the flywheel to the clutch shaft.

This is the ‘fitted’ position of the multi-plate clutch. By operating the clutches pedal, the force is lowered against the force of the springs, and contact is lost between the flywheel, the clutch plate, and the pressure plate, and no motion is transferred from the flywheel to the clutch shaft. This is the ‘decomposed’ condition for the multi-plate clutch.

Currently, multi-plate clutches are being used in all automobiles. A wet clutch is a type of friction clutches. Here oils are sprayed on the plates with the help of a nozzle.

They are used in various types of automobiles. the friction material used on the clutch plates must have a greater coefficient of friction and are perforated so that the oil can pass through them.

These clutches have intake for oil. A sump is placed at the bottom to extract the oil from which it is extracted. This type of clutches has a longer life than dry clutches due to better diffusion of heat.

Difference Between The Dry Clutch and Wet Clutch:

The differences between dry and wet clutches are as follows:

Dry Clutch;

A dry clutch has a high coefficient of friction.
The coefficient of friction for dry operations is 0.3 or more.
A dry clutch has a higher torque capacity than a wet clutches of the same dimensions.
For the dry clutches, it is necessary to prevent contamination due to moisture or surrounding lubricating machinery by providing a seal.
Heat flames are more difficult in dry clutches.
The wear rate is much higher in dry clutches than in wet clutch.
Engagement in the dry clutch is rough compared to the wet clutch.

Wet Clutch;

The friction coefficient is reduced due to oil in wet clutches.
The coefficient of friction for wet operation is 0.1 or less
The torque capacity of wet clutches is less as compared to the torque capacity of the dry clutch of the same dimensions.
Preventing contamination due to moisture or lubricating machinery nearby is not necessary for wet screws.
In wet clutches, lubricating oil removes friction heat.
The wear rate is much lower in wet clutches than in dry clutches. The wear rates in wet clutches are about 1% of the expected rate in dry clutches.
In wet clutches, the working of the clutch is stirred to provide a passage for lubrication. This reduces the net face area for transmitting torques.

Construction and Operation of The Multi-Plate Clutch:

A multi-plate clutches are provided with more than one friction plate.
In fact, in this clutch, there are two pressure plates and two friction plates, as shown in the figure below.

These pressure plates are attached to the clutch cover via studs. This clutch cover is fitted in a flywheel.
A friction plate is placed between the first and second pressure plate, and the second one is between the pressures plate and the flywheel.
The link mechanism is similar to that used in a single plate clutch.
The two friction plates are attached to the clutch shaft using a spline arrangement.
While the flywheel is rotating, the pressure plates rotate and press against the friction plate. This causes the friction plates and thus also to rotate the clutch shaft.
When the pedal is pressed, the flywheel rotates, but the friction plates come out.
This is because they are not completely suppressed by pressure plates.

Advantages of Multi-Plate Clutch:

Here, the different Advantages of the multi-plate clutch are as follows

The number of friction surfaces increases the ability of the clutch to transmit torque, although the size remains fixed.
Therefore, considering the same torque transmission, the overall diameter of the multi-plate clutch is reduced compared to the single-plate clutch.
Due to this advantage, this type of clutch is used in some heavy transport vehicles and racing cars.
This multi-plate clutch is used in scooters and motorcycles where there is limited space.

FAQ

What Is a Single Plate Clutch?

A single plate clutch consists of a clutch plate with friction lining on both sides, positioned between the flywheel and the pressure plate. It operates on the principle of friction and can be of two types: helical spring type and diaphragm spring type.

What Are the Main Components of a Single Plate Clutch?

The main components include the clutch plate, pressure plate, springs, and flywheel. Each part plays a crucial role in the clutch’s operation, from transmitting torque to engaging and disengaging the clutch.

How Does a Single Plate Clutch Work?

When the clutch pedal is not pressed, the clutch plate is engaged between the flywheel and pressure plate, allowing torque transmission. Pressing the clutch pedal disengages the clutch plate, allowing the flywheel to rotate without affecting the clutch shaft.

What Are the Advantages of a Single Plate Clutch?

Advantages include smooth operation, low power loss, minimal heat production, and fast operation. It is also simpler in design compared to multi-plate clutches.

What Are the Disadvantages of a Single Plate Clutch?

Disadvantages include lower torque transmission capacity, larger size for low torque applications, susceptibility to moisture damage, and higher wear and tear.

What Is a Multi-Plate Clutch?

A multi-plate clutch contains more than one friction plate, which increases the contact area and torque capacity. It is used when a single plate clutch cannot handle the required torque.

How Does a Multi-Plate Clutch Work?

In a multi-plate clutch, multiple friction plates are pressed between the pressure plates and flywheel. The engagement and disengagement are controlled by the clutch pedal, similar to the single plate clutch, but with increased surface area for torque transmission.

What Are the Advantages of a Multi-Plate Clutch?

Advantages include increased torque transmission capability, reduced overall diameter compared to a single plate clutch for the same torque, and its use in compact spaces like motorcycles and racing cars.

What Is the Difference Between a Dry and Wet Clutch?

A dry clutch has a higher coefficient of friction, higher torque capacity, and higher wear rate, while a wet clutch uses lubricating oil, which reduces friction coefficient, lowers wear rate, and requires oil management for cooling.

Where Are Multi-Plate Clutches Commonly Used?

Multi-plate clutches are commonly used in racing cars, heavy transport vehicles, and motorcycles where space is limited and higher torque transmission is required.