Note

1. DJJ6153
CHAPTER 5 : CLUTCHES
AND BRAKES
Nama Pelajar: Muhamad Arief Haekal Bin Zainolazam
(14DKM18F1124)
Nama Pensyarah: Encik Zahrin Bin Tokijan

2. Function of Clutch and Brakes
The function of a clutch is to engage or disengage a machine (or machine component) without
starting or stopping the driver. Different types of clutches can also provide the following:
◦ Slower, smooth engagement and disengagement under full speed.
◦ Quick engagement and disengagement.
◦ Overload protection by limiting the maximum torque loads.
◦ Prevention of accidental machine reversal.

3. Types of Clutches
Mechanical Clutches
Electrical ClutchesHydraulic Clutches

4. Mechanical Clutches
Friction Widely used in industry (i.e. automotive industry).
Jaw Clutches Usually used on slow speed applications.
Centrifugal
Clutches
Friction type centrifugal clutches are commonly found in applications
where it is desirable to have either no load starting or protection against
overload.
Over-running
Clutches
Frequently used on machine where the driving motor or media requires
protection.
Torque limiting
Clutches
Used on any number of different pieces of equipment or also used with
roller chain type coupling.
Tooth Clutches Used pneumatic of hydraulic actuating cylinder to operate.

5. HYDRAULIC CLUTCHES
Fluid Clutches
• Widely used in industry because of their ability to start
under heavy loads and absorb shock loads.
• Also used to provide a smooth flow of power to the driven
side of a machine. (Also known as fluid coupling).
• The driven half of a fluid coupling is actuated by the
hydraulic fluid.
• The driving half (pump/impeller) and driven half (turbine)
will rotate at the same speed during operation.

6. Electric Clutches
1. Used where intermittent motion is required especially to start and
stop the drive motor on short time cycles.
2. A magnet or coil is mounted on a driven component or machine
while an armature plate is mounted on the driving motor or shaft.
3. When the two parts are de-energized, no contact or action takes
place between them, even though the motor the motor may be
running.
4. When an electric current is introduced into the magnet or coil, a
magnetic field is set up causing the armature and the coil to draw
together.
5. This action then couples the two halves electrically and physically
causing them to rotate as one piece.

7. Disassemble Clutch Brake
1. Remove the engine from the car.
Note: The pressure plate assembly and clutch disk remain on the flywheel when you
remove the engine. The clutch release (throw-out) bearing and related parts stay in
the transmission. If the old pressure plate is to be reused, scribe or paint alignment
marks on the pressure plate and the flywheel to ensure proper realignment of the
pressure plate during reassembly.
2. Hold the pressure plate securely and completely, then loosen the pressure
plate-to flywheel bolts by turning each bolt only a little at a time. Work in a zig-
zag pattern until all spring pressure is relieved. Then remove the bolts, followed by
the pressure plate and the clutch disc.
Caution: The pressure plate is under a great deal of spring pressure. If you work
your way around the plate, removing each bolt one at a time, it will warp.

8. 3. Clean the friction surface on the flywheel and inspect it for wear, cracks,
heat checking, grooves, and other obvious defects. Alternating bright
and dull areas indicate a warped plate. A machine shop can machine the
surface flat and smooth (highly recommended, regardless of the surface
appearance). Light glazing can be removed with medium grit emery
cloth.
4. Inspect the diaphragm spring fingers for excessive wear and make sure
they are not distorted.
5. Shake the pressure plate assembly and verify that the diaphragm spring,
which should be under tension, does not rattle. If the pressure plate is
defective in any way, replace it.
6. If you will be reinstalling the engine you removed, clean the flywheel and
pressure plate friction surfaces with lacquer thinner or acetone.
Caution: DO NOT use oil or grease on these surfaces or on the clutch disk
lining. And clean your hands before handling the parts.

9. 7. Inspect the clutch release (throw-out) bearing. If it feels gritty when you
turn it, or if it has been making noise, replace it.
8. Never wash the bearing in solvent since this will remove the factory-
installed lubricant. If the bearing is unserviceable, replace per the
procedure.
9. Inspect the lining on the clutch disk for wear. There should be at least
2mm of friction material remaining above the rivet heads.
10. Check the clutch disk for loose rivets, distortion, cracks, broken springs
and other obvious damage
Note: As mentioned above, ordinarily the clutch disk is routinely
replaced, so if in doubt the condition, replace it with a new one.
If you're planning to re-use the old clutch disk, it's a good idea
to check it for run out.

10. 11. Carefully inspect the splines inside the hub of the clutch disk and the
splines on the transmission input shaft. They must not be broken or
distorted. Lubricate the splines in the disk hub and the splines on the
input shaft with graphite or molybdenum disulfide powder (Rob's last
replacement clutch plate came with a tiny tube of special "spline" grease
to be smeared sparingly on the splines).
12. Verify that the clutch disk slides freely on the drive shaft splines without
excessive radial play. If the clutch disk is in any way unserviceable,
replace it.
Note: You're probably replacing the clutch disk anyway, but if the splines on
the input shaft are damaged, you'll have to replace the input shaft as well.
Note: If you are replacing the main oil seal, remove the flywheel at this point
and replace the clutch after the flywheel has been reinstalled.

11. Reassemble
1. Install the flywheel, if removed.
2. Clean the flywheel and pressure plate friction surfaces with lacquer thinner or
acetone.
Caution: DO NOT use oil or grease on these surfaces or on the clutch
disk lining. And clean your hands before handling the parts.
3. Position the clutch disk and pressure plate against the flywheel with the clutch held
in place with an alignment tool (the best alignment tool is an old input shaft, or
there is a commercially available inexpensive one made of plastic).
Note: Clutch Pilot Tool - Using the clutch alignment tool can take a lot of the headache
out of installing an engine. Instead of eyeballing to see if the clutch is centered, simply
install the clutch alignment tool into clutch disc, and tighten the pressure plate (a turn
per bolt, rotate around). The tool will keep the clutch disc centered so the engine goes
onto the transmission easier. After you are finished, simply pull the tool out, clean, and
save for the next time you need it!

12. Note: Lacking a centering tool, you can just get down to flywheel height and
"eyeball" it. The worst that can happen if it's not exactly centered is that the last
inch or so of engine installation might take a little more shoving.
4. Make SURE the clutch disk is installed properly (most replacement clutch plates
will be marked "flywheel side" or something similar. If not marked, install the
clutch disk with the damper springs towards the transaxle.
5. If you're reusing the old pressure plate, make sure the marks you made on the
pressure plate and the flywheel are matched up.
6. Install a clutch alignment tool into the center of the clutch disc you intend to
use. With the clutch disc on the alignment tool, install the tool into the end of
the crankshaft. Make sure that the alignment tool extends through the splined
hub and into the needle bearing in the gland nut. Wiggle the tool up-down
and/or side-to-side as needed to bottom the tool into the gland nut.
7. Make sure that the clutch disc is against the flywheel, then install the pressure
plate.

13. 8. Loosely start the six mounting bolts in the flywheel. Tighten them "crosswise",
back and forth across the plate to prevent distorting the cover. After all the
bolts are snug, torque them first to about 10 ft-lbs. and finally to 18 ft-lbs.
9. Center the clutch disk by ensuring the alignment tool extends through the
splined hub and into the needle bearing in the gland nut. Wiggle the tool up-
down and/or side-to-side as needed to bottom the tool into the gland nut.
10. Loosely install all of the mounting bolts. Tighten them "cross-wise", back and
forth across the plate to prevent distorting the cover. After all the bolts are
snug, torque them first to about 10 ft-lbs. and finally to 18 ft-lbs.
11. Install the clutch release bearing if removed. Be sure to lubricate the bore of
the release bearing and the outer surface of the central guide sleeve with high-
temperature grease, and apply multi-purpose grease to the contact areas of
the forks on the release shaft.
12. Reinstall the engine in accordance with our Engine Installation Procedure.
13. Adjust the clutch pedal free play in accordance with our Clutch Cable
Adjustment Procedure.

14. Clutches and Brakes Maintenance
Procedure
Check list clutches and brakes maintenance, symptoms and record observations for
preventive maintenance
1. Improper adjustment of clutch or brake: The clutch or brake may not be fully
engaging. Follow the manufacturer’s adjustment procedures.
2. Oil or contaminant on friction surfaces: Clean or replace the surfaces.
3. Worn out friction components: Check the components to see if they are within
tolerances. Replace them if necessary.
4. Worn linkage or parts used in engaging clutch or brake: Sometimes adjustment
is adequate to compensate for wear. Check for obstruction and corrosion on
moving parts. Clean or replace the parts as necessary. Check lubrication, and
relubricate if required.

15. 5. Too much torque: This may be because an increased load exceeds design
capacity or because of poor initial selection of a clutch or brake. Check
the machine to determine if the increased load is temporary or
permanent. Repairing or servicing a machine may reduce torque to
acceptable levels. If not, the clutch or brake should be replaced with one
designed for the increased torque loads required.
6. High-frequency cycling or high-inertia loads: Generally, these cases of
excessive heat can be solved only by changing to a clutch or brake with
greater heat-dissipation ability. Sometimes a fan or blower may be used
to increase air flow, thus cooling equipment. Shortening the slipping
time during start-up can also reduce heat. Less slippage means less heat,
but make sure that engagement is not so sudden that severe shock loads
are created in the machine. Engaging clutches under the lightest possible
startup loads is always recommended.

16. With any type of clutch or brake, the following are generally recommended:
1. The clutch or brake should always be the correct size for the application.
2. Heat dissipation should always be adequate to ensure long life and low
maintenance.
3. Lubrication, if required, should be done on a periodic, regular schedule.
4. Components should be checked regularly for adjustment and wear.
5. Clutches and brakes should be kept clean and free from debris whenever
possible.