Working Principle of a Disc Clutch:
The clutch principle is based on friction. When two rubbing surfaces come into contact with each other and unite by applying pressure on them. And, if one surface rotates, the other one rotates as well. Here rubbing action, means friction is working between both surfaces. Here, the one surface rotates first is a driving surface. And the other one which follows the first is a driven surface. The driving surface rotates as well after disconnection from driven. The friction between both surfaces depends on some factors that are (i). Working surface area (ii). Material’s Friction coefficient (iii). Applied pressure on both surfaces.
Working of a Clutch:
We have read in brief the working principle of a clutch in the above paragraph. Now we will read about the working method of a clutch. Let’s check this link Single Plate Clutch Working. In this animation, you can see basically how a single plate works.
In this video, you will see how a rotating disc (flywheel) rotates another co-axial disc with the help of friction. Hence, the driven disc rotates the splined shaft. This shaft provides motion to the gearbox.
Two co-axial shafts, one is driving and another one is driven shaft, shown below image. The clutch connects both shafts. A flywheel is mounted on the end of the driving shaft, which has a bearing as well. Bearing’s inner race holds the fore-end of the driven shaft.
While the driving shaft rotates, due to the freedom in rotational motion with the help of bearing, the driven shaft does not rotates. You can see it in the video.
Engagement of clutch:
When force releases from the thrust race, spring pressure pushes the pressure plate towards to flywheel. This pressure plate applies pressure on the clutch plate, it is locked on the splined shaft. By sliding on the shaft, when it comes in contact with the rotating flywheel. Due to the friction clutch plate also rotates. The locked splined shaft also rotates with the clutch plate.
Disengagement of clutch:
Thrust race is pulled by the clutch lever wire or link. It pulls the long end of the release lever. The small end of the lever pushes the stud screwed on the flywheel. Since the release lever is mounted on a pressure plate with the bracket. It pulls self towards to opposite to the flywheel as well as the pressure plate. This action disengages the clutch plate and flywheel.
The above image shows the disengaged clutch position.
Construction of a Single Plate Clutch:
A single plate consists of various small and major parts. Here we will do a study of some major parts. The above image demonstrates all of these major parts. The list of parts are as below:
The driving shaft is an output shaft of the engine. Right side in the image.
A heavy metal wheel attached at the end of the driving shaft. It makes smooth power delivery from the engine to the gearbox. A whole clutch assembly is arranged with the flywheel.
When an operator or driver pushes the clutch lever, It is the first most part that acts in a clutch assembly. It slides on the driven shaft in order to clutch lever actions. The Clutch lever pulls the thrust race and consequently, it pulls the release lever.
Release lever and Bracket:
Release lever plays a very important role to transfer force from clutch lever to pressure plate. It is pivoted with bracket and this bracket is fixed on the pressure plate. Lever’s one long end tangentially attached with the thrust race. And another end, which is short in length applies tangential force to the pin. When thrust race actuated by the clutch lever. Long end pulled by thrust race. Since the bracket pivots the lever, the short end pushes the pin. This pin fixed on the flywheel. That’s why this lever pulls the whole pressure plate subassembly apart from the flywheel.
Friction lining and clutch Plate:
Friction lining and clutch plate is the most important part of the clutch single plate clutch. The clutch plate is a metallic disc having friction lining both side faces. The clutch plate slides on the splined shaft between the flywheel and pressure plate. And the friction discs creates friction between flywheel and clutch plates. The pressure plate creates pressure on the clutch disc.
Pressure plate creates pressure to couple the clutch and flywheel. We can see springs and pressure caps creates pressure on the pressure plate. This pressure is a clamping pressure. When the driver presses the clutch lever, by the action of thrust race and release lever, this pressure plate pulled in opposite directions of the flywheel. At the same time, the clutch plate is displaced from the flywheel. And crank (driving) shaft and driven shaft starts to spin freely.
Driven shaft is the output shaft of the clutch lever. This is the input shaft for the gearbox. It’s one end (clutch side) splined, so it is a splined shaft. This shaft transfers power to the gearbox.
Applications of a Single Plate Clutch:
Almost we all know the clutch used in vehicles. But, single plate clutches are used where large space area is available. So bigger vehicles like buses, trucks and cars having the single plate type clutches, but not possible to use in small vehicles like bike, scooters.
The single plate clutches having a larger surface area so that dissipates heat easily. Hence, there not required any cooling oil. That’s why this is a dry type clutch.
Advantages and Disadvantages of a Single Plate Clutch:
- It has only one plate, so it operates easily and quickly.
- In this mechanism having very less power loss.
- It has a larger surface area, it will dissipate heat quickly.
- It provides very smooth operation during disengagement and engagement.
- Cheap and easy to manufacture.
- Torque transmission capacity is not enough good.
- Wearing and tearing properties are not really good.
- Higher maintenance is required.
- It requires a large space for assembling.