Clutches

A clutch assembly is located between which two major vehicle components when the vehicle is equipped with a manual transmission or transaxle?

Engine crankshaft and rear differential Output shaft and drive wheels Engine flywheel and transmission input shaft Torque converter and driveshaft

What is the primary purpose of the clutch assembly, allowing the engine to remain running when the vehicle is stopped and the transmission is not in neutral?

To increase output torque smoothly during acceleration. To prevent the transmission from exceeding engine RPM. To allow the engine to operate without putting the transmission in neutral. To dampen engine torsional vibrations during cruising.

In a friction clutch, the clamping force is typically provided by a spring or springs. This force may also be assisted by what secondary force, particularly in certain high-speed designs?

Torsional force Axial thrust Centrifugal force Hydraulic pressure

What is the functional state of the clutch when the clutch pedal is resting in the up position?

Disengaged, with no power flow. Freewheeling, allowing gear shifting. Engaged, allowing power flow to the transmission. Partially engaged, allowing up to 2% slippage.

When a push-type clutch is fully engaged at highway speeds, what is the maximum amount of slippage typically observed between the clutch disc and the flywheel/pressure plate assembly?

No slippage (0%) Typically no more than 2% Approximately 5% Up to 10%

Which type of clutch, classified by release bearing application, is most common in the heavy truck and equipment industry?

Push-type Diaphragm spring type Pull-type Semi-centrifugal type

When the operator steps on the clutch pedal, the push-type release bearing moves inward, causing the release levers to pivot. In which direction do the release levers move the pressure plate?

Away from the flywheel Toward the flywheel In the same direction as the disc Toward the clutch cover

In a pull-type clutch assembly, when the release bearing assembly is moved away from the flywheel, what is the immediate action this takes on the inner ends of the release levers?

Pushes them toward the flywheel. Pulls them away from the flywheel. Locks them to the clutch cover. Releases the fulcrum ring.

What is the specific function of the torsional springs located within the hub of a spring-dampened clutch disc?

To hold the clutch facings against the web. To adjust the clutch pedal free play. To absorb and dampen torque and engine power pulses. To cushion initial engagement against the flywheel.

Which spring component, constructed as a segmented, curved web of thin spring steel, provides cushioning during clutch application to ensure smooth engagement?

Torsional Load Spring Belleville Spring Marcel Spring Diaphragm Spring

The Torque Rating of a clutch assembly is defined as its ability to transmit torque. This rating is influenced by all of the following factors EXCEPT:

The applied force of the pressure plate springs. The coefficient of friction of the facing materials. The physical size of the clutch disc. The material of the clutch housing (aluminum or cast iron).

Which type of clutch spring design is also called a diaphragm spring?

Perpendicular Coil Springs Angled Coil Springs Torsional Spring Belleville Spring

What is the primary purpose of the small ball or roller bearing located in the bore of the flywheel or crankshaft?

To carry the axial load of the transmission input shaft. To reduce rotational friction when the clutch is engaged. To pilot (guide and align) the transmission input shaft. To transmit torque from the engine to the transmission.

According to the source, why must a flywheel that includes engine balancing weights be carefully handled?

Because the internal ring gear may fail if dropped. Because a flywheel from an externally balanced engine must not be installed onto an internally balanced engine (and vice versa). Because the dowel pins must never be removed from the friction surface. Because the precision ground surface is easily damaged by oil contamination.

Flywheels are typically constructed from what material due to its weight, low cost, and friction qualities?

Aluminum alloy Stamped steel Cast iron Sintered bronze

Which style of flywheel combines two surfaces, one for the clutch cover and one friction surface for the clutch disc, and is suitable for both single and double disc clutch assemblies?

Stepped Countersunk Flat Dual mass

What is the primary functional advantage of a stamped steel clutch cover compared to a heavy cast iron cover?

Stamped steel absorbs more heat during clutch operation. Stamped steel provides a more rigid structure under increased torque loads. Stamped steel is lighter and allows higher engine speeds to develop. Stamped steel allows the use of internal adjusting rings.

In heavy-duty applications, the clutch cover may be made of cast iron because this material provides which functional advantage?

Lighter weight for faster acceleration. A more rigid structure under increased torque loads and better heat absorption. Increased friction coefficient for the pressure plate. Elimination of the need for drive straps or lugs.

Pressure plate assemblies are considered drive members of the clutch assembly along with which other component?

Clutch disc (driven member) Clutch cover Flywheel Transmission input shaft

Which type of pressure plate spring arrangement is typically heavier than a diaphragm clutch for the same application and uses 6 to 12 coil springs standing at 90° to the pressure plate?

Angled Coil Springs Belleville (Diaphragm) Spring Perpendicular Coil Springs Torsional Load Springs

Some coil spring type clutches are classified as semi-centrifugal due to the addition of centrifugal weights. What is the purpose of these weights?

To allow the clutch disc to freewheel upon disengagement. To reduce clutch slippage by increasing the clamping force on the pressure plate at high engine rpm. To provide sufficient throwout bearing clearance during engagement. To absorb engine power pulses at low RPM.

A rigid clutch disc is typically used in applications where:

High torque and low speed are required. A limited amount of engagement and disengagement occurs. Maximum cushioning of clutch application is needed. The drive train requires heavy torsional dampening.

Dampened clutch discs utilize torsional springs in the hub. Under what conditions will these springs compress until the hub flange contacts the stop pins?

Under light torque loads. When the clutch is disengaged. Under high torque loads. When the engine is operating at low idle speeds.

What is the function of the holes usually drilled through the rivets used in mounting organic clutch facings?

To secure the rivets to the segmented steel web. To act as a wear indicator. To act as a vacuum break. To hold the Marcel springs in place.

Organic clutch disc linings are referred to as non-asbestos organic (NAO). Which materials are currently mixed into these linings to provide the correct combination of friction, strength, and durability?

Metallic and lead compounds Carbon and silica compounds Fibreglass, Aramid, and Kevlar Sintered bronze and high-carbon steel

Which type of clutch disc lining provides very good resistance to slipping, a long service life, and is commonly used in heavy-duty truck applications, despite causing premature wear on the pressure plate and flywheel?

Organic linings Semi-metallic linings Ceramic linings (ceramic button) Metallic linings

The radial grooves cut into clutch facings serve several functions, including cooling the clutch disc and providing a vacuum break. They also increase the unit pressure on the lining by achieving what physical result?

Increasing the total surface area of contact. Reducing the surface area on which the clamping force is applied. Reducing the coefficient of friction. Eliminating torsional load spring compression.

When two clutch discs are used in a high-torque application, what component is required between the two discs to provide the necessary friction surfaces that do not contact the flywheel or pressure plate?

Slave cylinder Intermediate plate Clutch cover Torsional dampener

An intermediate plate in a double disc clutch must be able to move slightly during the engagement and disengagement process. What happens if this plate is fastened too tightly?

The clutch brake will engage prematurely. The driven member will be locked to the drive member. One or both clutch discs will remain in contact with a friction surface on disengagement. The release bearing will contact the release fingers prematurely.

In heavy-duty dual mass flywheels, if any part of the complex unit fails, what specific replacement procedure is mandatory?

Only the failed component (primary or secondary flywheel) must be replaced. The secondary flywheel and clutch disc must be replaced as a set. The entire flywheel must be replaced. The ring gear must be removed and welded.

In terms of function, what type of load must the clutch release bearing withstand?

Radial load Axial load (thrust type) Torsional load Centrifugal load

What is the classification given to release bearings used in heavy-duty applications, based on the fact that they rotate only during the engagement and disengagement process?

Roller bearings Full-time spin bearings Intermittent use bearings Sintered bearings

What is the functional role of the clutch release fork in a standard push-type mechanism?

It pivots on a clutch cover pivot bolt to engage the clutch. It transmits engine noise and vibration back to the driver. It pivots on the ball stud in the clutch housing and pushes the release bearing forward to act on the release levers. It pulls the release bearing away from the pressure plate.

When an operator is shifting a heavy truck from neutral to first or reverse gear, what is the primary purpose of a clutch brake?

To absorb power pulses from the engine. To provide maximum heat dissipation. To slow the rotation of the clutch disc and transmission input shaft to prevent gear teeth clash. To increase the clamping force on the clutch disc.

A Torque-Limiting Clutch Brake is designed to slip internally above a pre-determined torque load. What failure does this action prevent, thus increasing service life?

Failure of the transmission input shaft splines. Breakage of the tangs on the clutch brake. Slippage of the clutch disc at high RPM. Premature wear of the clutch release bearing.

What advantage does a two-piece clutch brake offer over a conventional design?

It requires less lubricant. It operates cooler and can be replaced without removing the transmission. It provides a higher torque capacity. It requires a clutch release fork for operation.

The pilot bearing operates only as a bearing when the clutch is disengaged. At this time, what are the relative speeds of the crankshaft and the transmission input shaft?

Both shafts turn at the same speed. Both shafts remain stationary. The shafts are turning at different speeds. The input shaft rotates only 2% slower than the crankshaft.

The clutch housing (bell housing) may be made of cast iron, particularly for which type of application?

Front wheel drive vehicles Light-duty vehicles Heavy-duty use Applications requiring integral housing design

What critical function do the dowel pins or bushings in the back of the engine block serve when mating with the forward face of the clutch housing?

They allow for the mounting of the clutch cover. They ensure the clutch housing is properly aligned with the engine. They provide the mounting point for the clutch slave cylinder. They prevent engine noise and vibration transfer.

When supplying replacement clutch components, what critical piece of information, aside from the vehicle identification, should the parts technician obtain?

The length of the clutch release fork. The total weight of the clutch assembly. The size (diameter) of the clutch disc. The material of the transmission case.

Why is it standard advice to suggest and provide a release bearing and pilot bearing/bushing during any clutch service job?

Because these parts must be matched to the specific friction material used. Because they are included in every OEM individual parts package. Because the cost of these parts is minimal compared to the labour charges required to replace them later. Because they are the components most susceptible to torsional vibration.

What is the primary functional difference between a Dampened (Flexible) Clutch Disc and a Rigid Clutch Disc regarding vibration?

Rigid discs handle torque pulses better than dampened discs. Dampened discs are required for high RPM applications, while rigid discs are for low RPM. Dampened discs reduce torsional vibration, extending drivetrain component life. Rigid discs provide smoother clutch engagement due to the lack of springs.

Which type of actuation system is most susceptible to transmitting engine noise and vibration back to the driver, requiring frequent adjustment?

Hydraulic system Cable system Mechanical linkage system Integral slave cylinder system

A hydraulic clutch system uses a pushrod attached to the pedal arm that applies force to a single reservoir hydraulic master cylinder. This pressure is transferred via hydraulic lines to which other component near the clutch?

Clutch housing Slave cylinder Release bearing guide Master cylinder piston

In a compound failure scenario where the Pilot Bearing has failed, which related components should a parts technician also suggest for sales, according to Table 3?

Clutch fork boot and clutch fork pivot Only the transmission input shaft bearing retainer. Clutch assembly Pressure plate assembly and clutch fork pivot

When matching a new or rebuilt pressure plate assembly to an old unit, what critical design feature must a technician check?

The thickness of the intermediate plate. The coefficient of friction (must be ceramic). Pressure plate assembly design (diaphragm, coil spring, etc.). The length of the clutch release fork.

What operational condition is characterized by the clutch disc remaining stationary or turning slowly, while the flywheel and clutch cover/pressure plate assembly rotate at engine speed?

Clutch Engaged Freewheeling Clutch Disengaged Direct Drive

When the clutch is engaged, the flywheel, the pressure plate assembly, and the clutch disc rotate together. What is the relationship between their speed and direction?

They rotate in opposite directions at the same speed. They rotate in the same direction at slightly different speeds. They rotate together as a unit in the same direction and at the same speed. The driven components turn 2% slower than the drive components.

A Multi-disc clutch assembly (e.g., using an intermediate plate) provides which dual performance advantage over a single-disc clutch?

Handle more torque and handle more heat. Reduced weight and reduced maintenance costs. Increased slip resistance and smoother engagement. Faster disengagement and reduced clutch pedal effort.

Based on the concept of friction clutches, the disc (clutch assembly driven member) is splined to the transmission input shaft, allowing it to move freely along the shaft. What component holds the disc in place axially?

The pilot bushing/bearing. The clutch release fork. The release bearing retainer. The clutch is clamped between the flywheel and pressure plate.