Centrifugal Clutch: What Is It and How Does It Work? The centrifugal clutch is a clutch system used in some motorcycles and operates differently than other types of clutches.
If your motorcycle operates with an automatic transmission, you can likely find among its key components, the centrifugal clutch, which has the common feature of remaining disengaged during its resting state.
It’s one of the most crucial systems of your motorcycle. To understand how it works, this article provides a descriptive concept, as well as a brief overview of its structure, its influence on your motorcycle’s performance, and the main problems it can encounter.
What is a Centrifugal Clutch?
The centrifugal clutch is a type of clutch system used in some motorcycles and small vehicles. Its primary function is to simplify driving, facilitating the starting and stopping of the vehicle without manually operating the clutch.
How does it work?
The centrifugal clutch operates based on the centrifugal force produced by the engine’s rotation. It comprises two sets of components: the clutch drum and the clutch shoes. In single-speed motorcycles, the clutch drum is mounted on the engine’s crankshaft and rotates with it. However, in popular scooters, the drum is mounted on the rear wheel. The clutch shoes are housed inside the drum and are connected to the final transmission.
When the engine is idling or at low RPMs, the centrifugal force produced by the clutch drum’s rotation isn’t strong enough to overcome the springs’ force keeping the shoes in their resting position (disengaged). This lets the transmission stay disconnected from the engine’s rotation, allowing the vehicle to remain stationary.
However, as the engine’s RPMs increase, the centrifugal force becomes strong enough to overcome the springs’ resistance, causing the shoes to expand and press against the drum’s inner surface. This, in turn, transfers movement to the transmission and subsequently the vehicle’s wheels, allowing the vehicle to move.
When the rider accelerates, the engine’s RPMs increase, which increases the centrifugal force and engages the clutch. Releasing the accelerator decreases the engine’s RPMs and the centrifugal force, disengaging the clutch and allowing the vehicle to stop.
Components of the Centrifugal Clutch
The centrifugal clutch consists of several crucial parts working together for its operation. The most significant components include:
1. Clutch Drum:
The clutch drum is a piece mounted on the engine’s crankshaft (or the rear wheel) and rotates with it. This component is vital to produce the required centrifugal force to activate the clutch as the engine speeds up.
2. Clutch Shoes:
The clutch shoes are housed inside the clutch drum. They are designed to engage and disengage depending on the centrifugal force generated by the engine’s rotation, making it an automatic clutch system.
Made of friction materials that allow them to grip each other under compressive forces, it’s common to need to replace the clutch shoes occasionally.
3. Compression Springs:
Compression springs are positioned between the clutch shoes and help keep them apart when the engine rotates at low RPMs. As centrifugal force increases, these springs decompress, allowing the shoes to grip each other and transfer movement to the transmission.
4. Friction Linings:
Clutch shoes and the pressure bell are typically lined with friction materials like ceramic or composite materials. These linings ensure grip between components under compressive forces, facilitating motion transfer.
Collectively, these parts work harmoniously to enable the centrifugal clutch to engage and disengage automatically based on the engine’s RPMs, simplifying the vehicle’s start and stop without the driver’s manual intervention.
Motorcycles with Centrifugal Clutch
The centrifugal clutch is commonly used in a wide variety of low-power vehicles with automatic transmissions, especially motorcycles and small vehicles designed for specific tasks. It is often associated with automatic transmission systems like the variator, automating both the clutch’s function and the “gear” shifting to make driving as straightforward as possible.