Clutch - Introduction | Necessity of clutch in automobile | Different types of clutches are as follows
1.0 Introduction
At starting speed the engine has a very low torque. The engine can not therefore be started under load. This requires the transmission system to be able to connect and disconnect the motor from the rest of the transmission system. The vehicle occupants must be operated smoothly and without shock. Therefore, the device that is used to mount and disconnect the motor is called a clutch. The clutch allows for gradual loading when operated properly, prevents jerky vehicle movement and prevents excessive stress both on vehicle parts and on passengers.
1.1 Necessity of clutch in automobile
The clutch is a device needed to transmit the power from the motor to the vehicle's wheels by gradually moving the motor to the transmission system, without giving the jerks for the car bodies.
Types of clutches : In construction and operation, the clutches used in motor vehicles are almost similar. Description of their relations and in the pressure plate assemblages are certain to differ.
1.2 Different types of clutches are as follows
1. Friction clutch
(a) Single plate
(b) Multi plate clutch
(i) Wet clutch
(ii) Dry clutch
(c) Cone clutch
(i) Internal
(ii) External
2. Centrifugal clutch
3. Semi centrifugal clutch
4. Conical spring clutch
5. Positive clutch
(a) Dog and spline clutch
6. Hydraulic clutch
(i) Single plate clutch
In engine vehicles, it is the most common type of clutch. The clutch consists basically of two parts, one on the driving shaft and the other on the driven shaft. These two shafts are both parallel and concentric, one shaft is fixed to the box while the other shaft is split so it can axially be moved. By increasing the efficient contact radius, the driving torque can be increased.
Construction:
The flywheel, clutch plates, clutch plates, clube cover, jacket levers, jetting levers, jumping gap and bearings, main shaft, and clutch shaft are all available for power transmission.
(a) Fly wheel: Fly Wheel is an integral part of the engine, also an embrace. It is a driving member and is connected to the clutch shaft pressure platform with fly-wheel bearings.
(b) Clutch plate or Disc: It is the driven part of the single platform clutch, and is filled with friction material on both surfaces. The central hub with inner splines restricts the movement of the axis along the split gearbox.
(c) Pressure plate: It's also a motorist. It presses the clutch plate to the flywheel between the pressure plate and the clutch cover. When the released heavers have to be depressed by the clutch foot, the pressure furnaces are mounted on the pressure plate.
(d) Clutch cover: This is the driver of the flywheel-bound assembly. The clutch plate usually turns with the flywheel, but both the flywheel and the pressure plates can be rotated when the clutch is removed.
(e) Release levers: These are pivoted on pins to the clutch covers, their outer ends are located and positioned on pressure plate lugs and the inner ends are projecting towards the clutch shaft .
(f) Withdrawl fork and bearing: This fork carrying the withdrawl bearings and pivoted on a balls, mounted in the clutch outer casing.
(g) Clutch shaft: It's a part of the gearbox, actually. As the shaft is spread over the hub that slides over the clutch plate. It has a one end that is supported in the center of the treadmill in a spigot bush and one end is equipped with a constant mesh truck.
Working of single plate clutch
When the clutch is disconnected the pad is pressed, the pressure plate reverses the force of the spring, and then, between the flywheel and the press plate, the clutch plate becomes unbroken.
The floor wheel then stays spinning as the engine runs and the storm shaft speed gradually reduces and it eventually does not rotate.
On the clutch, the clutch plate is struck between the flywheel and the pressurized platform. Since the friction plate lines on both surfaces of the clutch plate and the pressure plate friction between the flywheel, the clutch revolves with the flywheel. As the clutch plate turns around, the clutch also turns around and is then rotated with the transmission (getar box). The control of the engine is therefore shifted from the shaft to the seizure tube.
(ii) Multi plate clutch
A clutch having more than three disc is called a multi plate clutch . This multi plate clutch is used where the space is limited, consist of a number of clutch plates, instead of only one clutch plate, as in the case of single plate clutch. The increased number of the clutch plates obviously increases the capacity of the clutch to transmit more torque.Due to this, these clutch plates are used in heavy duty commercial vehicles, racing cars, special purpose military vehicles etc. These may be dry or wet. When the clutch of this type is operated in a oil bath , is called a wet clutch. The oil acts as a cushion to provide a smooth engagement. The energy released as heat is also carried away by the oil . This reduces the operating temperature and prolongs life. The dry clutch is used without oil having driving plates lined on each side with a frictional material .The function of dry clutch is similar to wet clutch.
In the multi-platform clutch like internal drum, which has several panels separated as its external outer edge is connected with the gearbox shaft. Another drum is clamped against the flywheel.
The plates turn on the drum, but axially slide. A spring maintains the external and internal plates are pressed together to transmit the driving power to the driven number. By pulling the internal drum against the pressure spring, the clutch is disconnected.
(iii) Centrifugal clutch
Several systems have been designed to make clutch operation automatic and this avoids the incorporation of a clutch pedal. A centrifugal clutch which automatically disengages itself when the speed falls below and again engages when the speed rises above a pre-set value is one such device . This clutch uses the centrifugal force instead of spring force for keeping it in engaged position.
The centrifugal clutch operates with the engine speed.As the speed increases the centrifugal weights fly off.These centrifugal weights pressurises the pressure plate and moves towards the flywheel.Inbetween the pressure plate and fly wheel ,the clutch plate is positioned .When the pressure pate pressed towards flywheel ,the clutch plate is sandwitched between fly wheel and pressure plate, and the power flows towards the gear box. The main disadvantage of this clutch is that it will not engage at speeds.
(iv) Semi centrifugal clutch
The only difference with these clutches is that both centrifugal force and the spring strength are used to hold them in a tied position. The only difference is that these clutches. The flowers are designed for the normal speed transmission of the torque, whereas the centrifugal force supports the transmission of a torque at a greater rate.
It consists of three lines and weighted levers and three clutch fountains which alternatively lie on the pressure plate at the same space. The flows hold the clutch on the pressure plate at normal speeds when the power transmission is small. The weights are removed and the heels exceed pressure on the plates at high speeds when the power transmission is high, thus maintaining the clutch strongly.
Summary
1. Clutch is a device to engage and dsiengage the engine with transmission system.
2. Different types of clutches are (i) Single plate (ii) Multi plate (iii) Centrifugal (iv) Semi centrifugal
3. Single plate clutch is used in motor vehicles for producing a quick engagement.
4. Multi plate clutch having more than 3 clutch plates having increased transmission torques used for heavy commercial vehicles.
5. Centrifugal clutch allows automatic engagement of clutch using centrifugal force instead of spring.
6. Semi centrifugal clutch uses both centrifugal force as well as spring force in keeping the clutch in engaged position.
Activity
1. A learner should observe carefully the section models of different types of clutches.
