Single Plate Clutch – Types, Working, Application & Diagram

What Is Single Plate Clutch?

A single plate clutch has one clutch plate. This clutch works on the principle of friction. It is the most common type of clutch used in motor vehicles. The clutch primarily consists of two members, one mounted on the driving shaft and the other on the driven shaft.

These two shafts are parallel and concentric with each other; one shaft is fixed to its housing while the other is splined so that it can move axially. The driving torque can increase by increasing the effective radius of contact.

Introduction

In the transmission system, the system by which power develops by the engine transmits to road wheels to propel the vehicle. In automobiles, the power develops by the engine which use to turn wheels. Therefore, the engine is to connect to the transmission systems for transmitting power to wheels.

Also, there should be a system using which the engine could be engaged and disengaged with the transmission system smoothly and without shock so that the vehicle mechanism is not damaged and passengers do not feel inconvenience. A clutch is employed in automobiles for this purpose.

A Clutch is a mechanism used to connect or disconnect the engine from the rest of the transmission elements. It is located between the engine and gearbox. The clutch disengages for starting, changing gears, stopping, and idling. The function of the Clutch is to permit the engagement or disengagement of gear when the vehicle is stationary and the engine is running without damaging gear wheels. So, we come back to our point of Single Plate Clutch and let us start.

Construction Of Single Plate Clutch

  • A single plate clutch consists of different parts for proper working. They are arranged in a systematic order.
  • Mainly it consists of a clutch plate with both side friction lining and some other parts which help in the proper functioning of a clutch like a flywheel, pressure plate, thrust bearing, hub, springs, and input mechanism for engagement and disengagement of the clutch.
  • The clutch plate attaches to the hub between the flywheel and the pressure plate, it moves axially on the driven shaft.
  • In a single plate clutch, the clutch plate should have both side friction lining because it mounts between the pressure plate and flywheel, friction is responsible for the torque transmission.
  • The pressure plate engages with the flywheel and springs. Pressure plate helps to push the clutch plate with the flywheel.
  • A lever attaches to thrust bearings with some mechanism on the driven shaft which transmits input and output motion from the clutch pedal.
Single Plate Clutch
Single Plate Clutch Diagram

Parts Of Single Plate Clutch

A single plate clutch assembly for transmission of power consists of a flywheel, a clutch plate, pressure plate, clutch covers, release levers, primary or clutch shaft.

1. Flywheel

The flyWheel is an integral part of the engine, which also use as a part of the clutch. It is a driving member and connects to the pressure plate of the clutch shaft is houses with bearings in a flywheel. The flywheel rotates as the engine crankshaft rotates.

2. Pilot Bearing

The pilot bearing or bushing press into the end of the crankshaft to support the end of the transmission input shaft. The pilot bearing prevents the transmission shaft and clutch disc from wobbling up and down when the clutch releases. It also assists the input shaft center of the disc on the flywheel.

3. Clutch plate or Disc plate

It is the driven member of the single-plate clutch and line with friction material on both surfaces. It has a central hub with internal splines to limit the axial travel along the splined gearbox driving shaft.

This helps to provide damping actions against torsional vibrations or variations of the driving torque between engine and transmission. A clutch disc is a plate between flywheel and friction or pressure plate. It has a series of facings inverters on each side to enlarge the friction. These clutch facings are made of asbestos material. They are highly worn and heat resistant.

4. Pressure plate

The pressure plate is made of special cast iron. It is the heaviest part of the clutch assembly. The main function of the pressure plate is to establish even contact with the driven plate facing through which the pressure springs can exert a sufficient force to transmit the full torque of the engine.

The pressure plate presses the clutch plate on to the flywheel from its machined surface. Between the pressure plate and clutch cover assembly, pressure springs are fitted. The pressure will be withdrawn from the flywheel whenever release levers are depressed by the toggle or release levers are pivoted accordingly.

5. Clutch cover

The clutch cover assembly bolts to the flywheel. It consists of a pressure plate, release lever mechanism, clutch cover, and pressure springs. Generally, the clutch plate revolves with the flywheel. However, when the clutch has disengaged, the flywheel, as well as the pressure plates, are free to rotate independently from the driven plate and driving shaft.

6. Release levers

These pivots on pins to the clutch cover, their outer ends locate and positions on pressure plate legs, and the inner ends are projecting towards the clutch shaft. A careful and accurate adjustment of the release mechanism is one of the most important factors governing the performance of a clutch assembly.

7. Clutch shaft

It is a component of the gearbox. Since it is a splined shaft to the hub of the clutch plate, which is sliding on it. One end of the clutch shaft attaches to the crankshaft or flywheel and the other end connects to the gearbox or forms a part of the gearbox.

Types Of Single Plate Clutch

1. Diaphragm Spring Type Single Plate Clutch

The construction of this type of clutch is similar to that of the single plate clutch. In this type of clutch diaphragm springs (also called Belleville springs) are used instead of the ordinary coil springs. In the free condition, the diaphragm spring is of conical form but when assembled, it is constrained to an approximately flat condition because of which it exerts a load upon the pressure plate.

The diaphragm spring is supported on a fulcrum retaining ring so that any section through the spring can be regarded as a simple lever. The pressure plate is axially movable, but it is fixed radially with respect to the cover. This is done by providing a series of equally spaced lugs cast upon the back surface of the pressure plate. The drive from the engine flywheel is transmitted through the cover, pressure plate and the friction plate to the gearbox input shaft.

The clutch is disengaged by pressing the clutch pedal which actuates the release fingers by means of a release ring. This pivots the spring about its fulcrum, relieving the spring load on the outside diameter, theraeby disconnecting the drive.

2. Helical Spring Single Plate Clutch

The clutch plate is mounted on the splined shaft and can move along the axis of the shaft. There is no relative movement between plate and shaft as far as rotational movement is concerned.

Both have the same rotational movement due to splines provided on the shaft. The flywheel is mounted on the engine crankshaft and rotates with it. The pressure plate is bolted to the flywheel through clutch springs. It can slide freely along the axis of the clutch shaft.

The clutch is engaged due to the force exerted by the clutch springs. This force causes contact between the pressure plate, clutch plate, and flywheel. The clutch plate is located between the flywheel and the pressure plate. The clutch plate is provided with friction material on both sides.

The rotary movement from the flywheel is transferred to the clutch plate and the clutch shaft due to friction. The clutch shaft also acts as the output shaft.

When the clutch pedal is pressed the clutch is ‘disengaged.’ The pressure plate moves back against the force of springs, and the clutch plate becomes free between the flywheel and the pressure plate.

Thus, the flywheel continues to rotate as long as the engine runs but the speed of the clutch plate declines and becomes zero. In this situation, motion is not transferred to the clutch shaft.

3. Single Plate Clutch With Dual Mass Flywheel

In modern automobiles, there is an increase of noise sources due to insufficient natural damping arising on account of lesser vehicle mass. Besides, aerodynamically optimized bodies producing low wind-noise make other noise sources more noticeable. Other factors are the lean fuel concepts, very low idling speed engines, 5 or 6 or more speed transmission and high-velocity lubricating oils. Coupled with these are the torsion vibrations in the powertrain caused by aperiodic combustion processes in the I.C. engines, appearing as gear rattle and body boom. In addition, the use of more fuel-efficient, low-emission transversely placed engines produces greater torsional irregularities, especially in case of Direct Injection diesel engines, necessitating the fine-tuning of damping systems for torsional vibration in the power trains.

It is seen that this can be achieved effectively by dividing the flywheel into two discs, viz., the primary flywheel with starter ring gear on the engine side and the secondary flywheel which goes to increase the mass moment of inertia on the transmission side. Luk of Germany was the first manufacturer to develop such a clutch. In this the mass of the conventional flywheel is split into two. One part continues to belong to the engine’s mass moment of inertia, while the other part goes to increase the mass moment of inertia of the transmission.

The two decoupled masses (primary and the secondary flywheel) are linked by a spring/ damping system. The clutch function is between the secondary mass and the transmission. Engine’s moment of inertia is now assigned to the primary mass of the DMF (Dual Mass Flywheel) while that of the transmission is assigned to the secondary mass including the clutch disc and the clutch pressure plate. Increasing the transmission mass moment of inertia causes the resonance speed (which generates noise) to fall from about 1300 rpm to about 300 rpm thus eliminating the engine noise since the engine is not operated in this speed range.

An incidental advantage of this is that shifting of transmission is now easier because of the lesser mass to be synchronised. The synchronisation wear is also less.

The dual-mass flywheel is quite efficient at reducing neutral gear rattle and improving manual transmission shift quality in performance cars. It may even be more important in heavy-duty diesel trucks where it suppresses larger torsional spikes which can damage transmission gear teeth.

Also, Read : What is Clutch?

Working Of Single Plate Clutch

Single Plate Clutch
  • In the Clutch the three parts needs. These are the engine flywheel, a friction disc or a clutch plate and a pressure plate.
  • Some springs give axial force to stay the clutch in the engaged position. When the engine is running and therefore the flywheel is rotating, the pressure plate also rotates because the pressure plate attaches to the flywheel. The friction disc is located between the flywheel and the pressure plate.
  • When the driving force has pushed down the clutch is released. This action forces the pressure plate to move away from the friction disc against the force of pressure springs. With this movement of the pressure plate, the friction plate is released, and therefore the clutch disengaged.
  • When your foot is off the pedal, the springs push the pressure plate against the clutch disc, which successively presses against the flywheel. This locks up the engine to the transmission input shaft, causing them to spin at the same speed.
  • The quantity of force the clutch can hold depends on the friction between the clutch plate and the flywheel, and in this way, much force the spring puts on the pressure plate.
  • When the clutch presses, the piston pushes on the release fork, which presses the throw-out bearing against the center of the diaphragm spring. As the middle of the diaphragm spring pushes in, a series of pins near the outside surface of the spring causes the spring to pull the pressure plate away from the clutch plate. This releases the clutch from the spinning engine.

Also, Read : What Is Multi Plate Clutch?

Application Of Single Plate Clutch | Single Plate Clutch Application

Single plate clutches are used where large radial space is available. e.g. cars, buses, and trucks.

Also, Read : What Is A Cone Clutch?

Advantages Of Single Plate Clutch

  1. The working of engagement and disengagement is very smooth in a single plate clutch.
  2. Power losses are very less.
  3. As sufficient surface area is available for heat dissipation in such clutches, no cooling oil is required. Therefore, single plate clutches are dry type.
  4. Single plate clutches have a quick operation and respond fast.
  5. It makes it easier to change gears than a cone type.

Disadvantages Of Single Plate Clutch

  1. Single plate clutches have high wear and tear rate.
  2. It has less torque transmitting capacity.
  3. The springs have to be the more stiff hence greater force requires to disengage.
  4. It requires high maintenance.
  5. The space required to accommodate the clutch is more as compared to the multi-plate clutch.

Also, Read : What Is A Centrifugal Clutch?

FAQ – Single Plate Clutch

Q. What Is Single Plate Clutch?

A Single Plate Clutch has one clutch plate. This clutch works on the principle of friction. It is the most common type of clutch used in motor vehicles. The clutch primarily consists of two members, one mounted on the driving shaft and the other on the driven shaft.

Q. What is applications of Single Plate Clutch?

Single plate clutches are used where large radial space is available. e.g. cars, buses, and trucks.

Q. Why do we use Single Plate Clutch in heavy vehicles?

Single plate clutches are used in cars, buses and trucks because of the larger size of the engines of these vehicles. Hence, enough space is available to fit a single plate clutch to create maximum power transmission.

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