Clutch release bearings in detail

A clutch release bearing (also known as a ‘throwout bearing’ or ‘release bearing’) is a type of bearing specifically designed for use in automotive clutch systems. It plays a key role in clutch operation, ensuring that the clutch engages and disengages smoothly, thereby reducing wear and prolonging the life of the clutch and the entire drivetrain. The following is a detailed explanation of clutch release bearings:

 I. Clutch release bearing type and structure

There are various types of clutch release bearings, each type has its own unique structure and characteristics:

1. Needle Roller Bearings 

   - Structure: Containing a series of long, thin needle rollers which can withstand large axial loads.

   - Characteristics: Suitable for working in smaller spaces, capable of efficiently transmitting forces, and suitable for clutch release applications.

   - Application: Widely used in small and compact cars. 

2. Roller Bearings

   - Structure: Cylindrical rollers are used as rolling elements, the load carrying capacity and wear resistance are comparable with needle roller bearings, but the size is relatively large.

   - Characteristics: the number of rollers is larger, the line contact degree is small, suitable for the occasion that needs higher load carrying capacity.

   - Application: commonly used in heavy trucks and high-performance vehicles. 

3. Ball bearings

   - Structure: composed of a set of steel balls and inner and outer rings, with a low coefficient of friction.

   - Characteristics: They can maintain stability when rotating at high speeds and are suitable for applications requiring low friction and high speeds.

   - Application: Used in some high performance vehicles and racing cars.

4. Spring-loaded bearings with arched rings (Spring-loaded Bearings)

   - Structure: Made of lightweight, high rigidity materials with excellent profile and load carrying capacity.

   - Features: Can be designed to reduce the size and weight of bearings according to usage requirements.

   - Application: Suitable for vehicles requiring lightweight design.

5. Hydraulic Release Bearings (HRCB)

   - Structure: Uses oil pressure during clutch clutch operation to drive the release bearings.

   - Characteristics: Simple structure, simple parts and assembly process, but requires special attention to the sealing of the oil circuit and maintenance work.

   - Application: used in some modern high-performance vehicles.

 Second, the clutch release bearing function and characteristics

Clutch release bearing has the following functions and features:

1. Separation function:

   - Function: Through the axial movement of the bearing, the clutch pressure plate and friction disc can be separated, thus disconnecting the engine from the transmission system.

   - Working principle: When the driver presses the clutch pedal, the hydraulic system or mechanical lever system pushes the release bearing to move forward against the release lever of the pressure disc, so as to separate the pressure disc from the friction disc.

2. Load bearing and wear resistance:

   - Characteristics: High load bearing capacity and wear resistance, able to withstand the pressure and friction during clutch operation.

   - Material: Usually made of high strength alloy steel or tool steel to ensure its durability and reliability.

3. Self-lubricating:

   - Characteristics: Some of the clutch release bearings have self-lubricating function, which can reduce the consumption of grease and replacement frequency to a certain extent.

   - Design: Fully sealed structure and the use of high performance grease further enhance its durability and reliability.

4. Low vibration and noise:

   - Characteristics: A well-designed clutch release bearing can reduce vibration and noise and enhance driving comfort.

   - Effect: By optimising the internal structure and materials of the bearing, it reduces friction and vibration during operation.

 Application Scenarios of Clutch Release Bearings

Clutch release bearings are widely used in all kinds of automobile clutch systems, especially in manual gearboxes. As an important part of the clutch system, it is of great significance to ensure the normal operation and prolong the service life of the clutch.

 Maintenance and care of clutch release bearing

In order to ensure the normal operation and prolong the service life of the clutch release bearing, it is necessary to carry out regular maintenance and repair. This includes:

1. checking the lubrication situation: ensure that there is enough grease inside the bearing to avoid wear caused by dry friction.

2. checking the wear condition: check the wear condition of the bearings regularly, if abnormal wear or damage is found, they should be replaced in time.

3. Check abnormal sound: Pay attention to whether there is any abnormal sound when the clutch is operated, such as clicking sound or whistling sound, which may be a sign of bearing damage.

4. Regular replacement: Replace the release bearing regularly according to vehicle usage and manufacturer's recommendations to avoid further damage to the clutch system.

 V. Clutch Release Bearings Mainly Withstand Forces

The clutch release bearing is mainly subject to the following forces:

1. Axial force:

   - Source: When the driver depresses the clutch pedal, the force is transmitted to the release bearing through a series of mechanical mechanism, which pushes the release lever or release fork, and then separates the clutch pressure plate from the flywheel.

   - Characteristics: This is the most important force on the release bearing, which needs to be able to withstand frequent axial loads.

2. Radial force:

   - Source: Centrifugal forces due to high speed rotation and lateral forces that may be encountered in cases of imperfect alignment.

   - Characteristics: Although radial force is not the main bearing force, the separation bearing must be designed to withstand these complex loading conditions.

 Types of Release Bearings for Different Vehicle Models

The types of clutch release bearings used in different models can be categorised according to their structure and operating performance:

1. Push type clutches:

   - Bearing type: Push type release bearing.

   - Characteristics: It is usually necessary to have a toggle clamping spring to ensure the stability of the release bearing during axial movement.

   - Application: Widely used in most manual transmission vehicles.

2. Pull Type Clutch:

   - Bearing type: pull type release bearing.

   - Characteristics: Additional connecting parts such as pull release ring are required to ensure the stability of the release bearing during axial movement.

   - Application: Commonly used in some high-performance vehicles and commercial vehicles.

 Clutch Release Bearing Failure and Maintenance

Possible failures of the clutch release bearing include:

1. Noise: such as a clicking or whistling sound, which may be a sign of bearing damage or poor lubrication.

2. vibration: abnormal vibration during clutch operation may be caused by bearing wear or improper installation.

3. clutch slippage: the clutch will not fully disengage, possibly due to a failed or worn release bearing.

4. Premature wear: Premature bearing wear may be due to insufficient lubrication or improper use.

To ensure optimum performance and longevity, regular maintenance is important, including periodic inspections and proper lubrication.

 To summarise

A clutch release bearing is a type of bearing specifically designed for use in automotive clutch systems and has a wide range of types and construction features. It undertakes the important task of separating the clutch pressure plate and friction disc, and is characterised by load bearing, wear resistance, self-lubrication and low vibration and noise. In order to ensure its normal operation and prolong its service life, it needs to be regularly maintained and serviced. Correct selection, installation and use of clutch release bearings are essential to ensure the performance of the clutch system and to extend its service life.