Effects in Pneumatically Operated Friction Clutches:
Here’s how each factor affects a pneumatically operated friction clutch:
(a) Oil Contamination of Friction Pads:
- Reduced Frictional Coefficient: Oil acts as a lubricant, reducing the friction between the clutch plates. This can lead to clutch slippage, where the engine continues to spin but fails to transmit full power to the drivetrain. The clutch will not engage fully, resulting in a loss of power and acceleration.
- Glazing: In some cases, oil contamination can cause the friction material to overheat and glaze over. Glazing creates a smooth, hard surface that further reduces friction and worsens clutch slippage.
- Uneven Engagement: Oil contamination might not be uniformly distributed on the friction surfaces. This can lead to uneven engagement and a grabby feeling when engaging the clutch.
(b) Reduced Air Pressure:
- Incomplete Engagement: Pneumatic clutches rely on compressed air pressure to create the clamping force between the pressure plate and friction plates. If the air pressure is insufficient, the clamping force won’t be strong enough to hold the discs together effectively. This will lead to clutch slippage, similar to oil contamination, with a loss of power transmission.
- Delayed Engagement: With lower air pressure, it might take longer for the clutch to fully engage, causing a delay in power transfer and a sluggish response when changing gears or starting the vehicle.
(c) Distorted Friction Pads:
- Warping: Excessive heat, wear and tear, or manufacturing defects can cause the friction plates to warp. This can lead to uneven contact between the plates, creating a grabbing or shuddering sensation during clutch engagement.
- Reduced Contact Area: Warped plates may not make full contact with each other, reducing the effective friction surface area. This can lead to slippage and a decrease in torque capacity.
- Noise: Distorted plates can create grinding or scraping noises during clutch engagement due to uneven contact.
(d) Angular Misalignment:
- Premature Wear: If the clutch components, such as the pressure plate or flywheel, are not perfectly aligned, it can cause the plates to rub against each other at an angle. This leads to uneven wear and premature failure of the clutch components.
- Increased Friction: Misalignment can create unnecessary friction points between the plates, even when the clutch is disengaged. This can generate unwanted heat and contribute to wear and tear.
Clutch Drag: In severe cases, misalignment might prevent the clutch from fully disengaging, causing the vehicle to continue creeping forward even with the clutch pedal depressed.