Clutch

Chassis Drive-line Components

Clutche s

Copyright 2007 by Nelson, a division of Thomson Canada Limited.

Necessity of a clutch, requirements of a good clutch, constructional features and working of different types of clutch (like single plate/multi plate/cone/semi centrifugal/fully centrifugal/wet etc.) used in automobiles, calculation of surface area and number of driving and driven plates, nature of wear and tear each components, effect of misalignment and mis- adjustment of components, fluid coupling, trouble shooting in clutch systems.


An Automobile is fitted with a cone clutch have the following parameters: Face width of lining material = 0.071m Effective mean diameter = 0.285m External radius = 0.15m Coefficient of friction = 0.3 Axial force applied = 1050 N Moment of inertia of rotating parts = 4.4 kg.m2 Speed = 1225 rpm The clutch works under uniform wear condition. Calculate the time required to attain full speed & energy lost in sleeping. Working of clutch http://www.exedy.com.au/User_Uploaded_Files/flash/tech-centre/how-a-clutch-works.swf http://static.howstuffworks.com/flash/clutch-fig5.swf


Requirement of clutch Describe the various clutch components and their functions. Name and explain the advantages of the different types of pressure plate assemblies. List the safety precautions that should be followed during clutch servicing.Copyright 2007 by Nelson, a division of Thomson Canada Limited.

Flywheel mounts to the engine crankshaft Clutch Disk the friction material assembly that provides easy engagement and firm torque transference Pressure Plate: also known as Clutch Cover this is the spring-loaded surface that locks the clutch Throw out bearing: also known as Release Bearing Pilot bearing:-centers and supports the transmission input shaft (many cars do not have this bearing) Clutch cable: mechanical release mechanism for some vehicles Clutch Master Cyliner: force-multiplying cylinder for vehicles with hydraulic release mechanisms Clutch slave cylinder: used along with a Master Cylinder for hydraulic release mechanisms Misc.hoses, lines, brackets, linkages, etc varies from vehicle to vehicle


Function of the clutch: In an automobile clutch, the flywheel is connected to the engine, and the clutch plate is connected to the transmission. When your foot is off the pedal, the springs push the pressure plate against the clutch disc, which in turn presses against the flywheel. This locks the engine to the transmission input shaft, making them spin at the same speed. The amount of force the clutch can hold depends on the friction between the clutch plate and the flywheel, and how much force the spring puts on the pressure plate. When the clutch pedal is pressed, a cable or hydraulic piston pushes on the release fork, which presses the throw-out bearing against the middle of the diaphragm spring. As the middle of the diaphragm spring is pushed in, a series of pins near the outside of the spring cause the spring to pull the pressure plate away from the clutch disc. This releases the clutch from the spinning engine. Parts description: The Engine: The engine runs the car. Without it working well, car wont function. The backbone of the engine is the crankshaft, and it is the hardest working part of the engine. The crankshaft drives all belt-driven accessories, such as the water pump, the alternator, the A/C and the fan. But, its primary function is to change the give-and-return motion of the piston and rod into a circling motion that is transferred to the transmission, and drive wheels. As the fuel/air mixture in the cylinder burns, it forces the pistons down. Each piston is connected to the crankshaft by a connecting rod. As the piston goes down, the connecting rod causes the crankshaft to turn.


The Flywheel: The flywheel does a lot of things it acts as a balancer for the engine, reduces vibrations caused by cylinders firing, and it provides a smooth surface friction surface for the clutch. But the flywheels main function is to transfer engine torque (the turning effort produced by the pressure from the crankshaft on the pistons) from the engine to the transmission. The flywheel connects the clutch and the driveline to the engine. One side is bolted directly to the crankshaft, and one side is bolted to the clutch assembly. The clutch disc: Sandwiched between the flywheel and the pressure plate, the clutch disc is covered with friction material on both sides. The center of the disc called the hub is splined to match the splines on the input shaft of the transmission. Each clutch disc comes with a set of springs, located in the hub, called the torsion damper system. These springs are designed to cushion the engagement by absorbing a portion of the impact when the disc is squeezed between the flywheel and the pressure plate. In street applications, the central hub is a separate part connected to the clutch with marcel cushion springs. This absorbs any engagement impact. The Pressure plate: The Pressure Plate is, basically, a spring-loaded clamp that is bolted to the flywheel. The pressure plate presses the clutch disc and allows for the transfer of power to the transmission. The Throw-out bearing: When the clutch pedal is pressed down, this bearing also called the Release Bearing moves toward the flywheel. It pushes in against the pressure plates release fingers and moves them against the force of the plates springs. This action moves the pressure plate away from the clutch disc, interrupting the flow of power and reducing friction.


The clutch fork: This piece provides a lever action to engage or disengage the clutch. It forces the throw-out bearing into the pressure plate. The Trasmission: The Transmission provides several selectable gear ratios, which allows the driver to match the engine output to a variety of driving conditions. starting from a dead stop as we accelerate, the engine needs to spin quickly to make the necessary power to move the car. Once we reached the speed limit, the car needs less power to maintain speed. So, the transmission uses a high gear ratio (lots of power, but not much speed) during initial acceleration, when climbing hills. It uses a low ratio (lots of speed, but not much power) when we cruising.
















Clutch Operation The pressure plate is a large spring-loaded plate that engages the clutch by pressing the disc against the flywheel. The pressure plate moves away from the flywheel when the clutch pedal is depressed.continuedCopyright 2007 by Nelson, a division of Thomson Canada Limited.

Clutch Operation The clutch release bearing is operated by the clutch linkage. When the clutch pedal is depressed, the bearing moves toward the flywheel, depressing the pressure plate fingers and moving the pressure plate away from the clutch disc.continuedCopyright 2007 by Nelson, a division of Thomson Canada Limited.

Clutch Components

continuedCopyright 2007 by Nelson, a division of Thomson Canada Limited.

Clutch Components Clutch housing Connects engine and transmission and houses the clutch assembly.


Clutch Components Flywheel Acts as balancer for the engine. Adds inertia to the rotating crankshaft. Provides a surface for the clutch to contact.Copyright 2007 by Nelson, a division of Thomson Canada Limited.

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Clutch Components Clutch (input) shaft Projects from the front of the transmission. Usually has a pilot that rides in a bearing or bushing in the end of the crankshaft. The clutch disc is splined to the clutch shaft. When engaged, the clutch disc drives the continued input shaft.Copyright 2007 by Nelson, a division of Thomson Canada Limited.

Clutch Components Clutch disc Is covered with friction material. Transmits power from the engine crankshaft to the transmission input shaft. Torsional coil springs or rubber grommets allow the disc to rotate slightly in relation to the pressure plate while they absorb the torque forces. continuedCopyright 2007 by Nelson, a division of Thomson Canada Limited.

Clutch Components Clutch disc (cont) The clutch facings are riveted to wave springs, or cushioning springs, which cause the contact pressure on the facings to rise gradually when the clutch is engaged. These springs eliminate chatter by dampening the clutch engagement.continuedCopyright 2007 by Nelson, a division of Thomson Canada Limited.

Clutch ComponentsClutch disc


Clutch Components Pressure plate assembly Squeezes clutch disc onto flywheel. Can be engaged or disengaged. Acts like a spring-loaded clamp. Two common types, the coil spring and diaphragm (Belleville) spring design.continuedCopyright 2007 by Nelson, a division of Thomson Canada Limited.

Clutch ComponentsDiaphragm Spring Coil Spring


Clutch Components Release bearing Is operated by the clutch linkage. Presses against the pressure plate to release the clutch.continuedCopyright 2007 by Nelson, a division of Thomson Canada Limited.

Clutch Components Pilot bearings The purpose of the pilot bushing or bearing is to support the outer end of the transmissions input shaft. Allows the input shaft to rotate in the crankshaft.Copyright 2007 by Nelson, a division of Thomson Canada Limited.

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Clutch Linkage Clutch linkage transfers the clutch pedal movement to the release bearing. Mechanical clutch linkage uses shafts, levers, or a

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Clutch LinkageHydraulic clutch linkage consists of a master cylinder, hydraulic tubing, and a slave cylinder.


Service Precautions Always wear eye protection. Always wear an approved face mask capable of protection against inhalation of asbestos particles. Use the proper equipment to remove asbestos particles and dust. Dispose of materials containing asbestos properly.continuedCopyright 2007 by Nelson, a division of Thomson Canada Limited.

Service Precautions Always use safety stands when working under a vehicle. Always work in a well-ventilated area. Have a helper assist in removing a transmission. Place the gearshift in neutral and set the parking brake when running a stationary vehicle.continuedCopyright 2007 by Nelson, a division of Thomson Canada Limited.

Common Clutch Problems Clutch slippage Definition: With the clutch engaged, engine speed increases but vehicle speed does not. Before disassembly: Check linkage. Check for worn or binding parts. Check engine mounts.


Common Clutch Problems Other causes for clutch slippage Oil-soaked or worn disc facings Warped flywheel or pressure plate Weak pressure plate springs Contact between the release bearing and the fingers of the pressure plate


Common Clutch Problems Clutch chatter Definition: Shaking or shuddering when clutch is engaged. Before Disassembly: Check engine mounts. Check for leaks from rear main seal, transmission input shaft seal, and clutch slave cylinder.continuedCopyright 2007 by Nelson, a division of Thomson Canada Limited.

Common Clutch Problems Clutch noises These noises are usually caused by bad bearings or bushings. To diagnose, determine whether the noise changes with the clutch engaged or disengaged.


Common Clutch Problems Causes for damaged release bearings Misalignment Overheating Slippage Component damage


Common Clutch Problems Clutch vibrations Are usually caused by worn engine mounts, loose bolts, excessive flywheel runout, or flywheel and/or pressure plate assembly imbalance.

Dragging clutch Is usually caused by linkage problems, incorrect pedal adjustments, or defective clutch assembly.continuedCopyright 2007 by Nelson, a division of Thomson Canada Limited.

Common Clutch Problems Pulsating clutch pedal Is usually caused by broken or bent release levers, misaligned bell housing, or warped pressure plate, flywheel, or clutch disc.

Binding clutch Is usually caused by binding linkage or cables, defective clutch assembly, or improper installation.continuedCopyright 2007 by Nelson, a division of Thomson Canada Limited.

Clutch Service ChecksMeasuring flywheel runout and Crankshaft endplay


Clutch Service ChecksMeasuring clutch housing face runout


Hydraulic Clutch Problems Soft clutch pedal or excessive pedal travel Is usually caused by low fluid level. May be caused by a faulty master or slave cylinder.

Hard pedal Is commonly caused by binding linkage or swollen cups in the master or slave cylinder.continuedCopyright 2007 by Nelson, a division of Thomson Canada Limited.

Summary The clutch, located between the transmission and the engine, provides a mechanical coupling between the engines flywheel and the transmissions input shaft. The flywheel is the main driving member of the clutch.continuedCopyright 2007 by Nelson, a division of Thomson Canada Limited.

Summary The clutch disc receives the driving motion from the flywheel and pressure plate assembly and transmits that motion to the transmissions input shaft. The two purposes of the pressure plate assembly are to squeeze the clutch disc onto the flywheel and to move away from the clutch disc so the clutch disc can stop rotating. continuedCopyright 2007 by Nelson, a division of Thomson Canada Limited.

Summary Common clutch components include the clutch disc, pressure plate, release (throw-out) bearing, and clutch linkage. Clutch linkage can be mechanical or hydraulic. Common clutch problems include slippage, drag, chatter, pedal pulsation, and vibrations.Copyright 2007 by Nelson, a division of Thomson Canada Limited.

Clutch

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thomson canada

transmissions

defective

common clutch

pressure plate

transmission

check engine

input shaft