Cam Clutches Basics: Here is All that You Need to Know

Cam clutches, also referred to as overrunning clutches, are used to help freewheel run in one direction and driving shaft in a different direction of rotation. When the clutch detects the driven shaft is moving faster than the driving shaft, it disconnects them automatically. In a bicycle, this type of clutch allows a person to coast without moving the pedal. This means that you can easily move downhill without paddling.

These clutches are common in heavy equipment, such as industrial motors and conveyor belting systems. This post takes a closer Look at cam clutches to demonstrate how they work. 

Cam Clutches Design and Configurations

Although the commonest example of cam clutches is a bicycle, you can find them almost in any piece of industrial equipment. For example, they are commonly used to connect coaxial shafts. While the operating principle of cam clutches is the same, they can have different designs. Here are some of the common configurations that you might get: 

• Self-tensioning helical springs. 
• Circular cylinder and eccentric rollers. 
• Ratchet and jaw configuration. 

Each of the three configurations is used to design a different cam clutch. You can get them in different machines, from grinders to material handling equipment, where variable transmission is needed. Also, arresting devices that require clutches to avoid reverse rotation also use cam clutches. 

After starting heavy machinery, you need the engine to start running freely as it picks up speed. A cam clutch makes this happen by allowing the starter motor to rotate the machine at a specific speed, and when the internal combustion engine roars to life and starts moving at a faster speed, it disconnects automatically. This means that the driven shaft, which has now started moving faster, cannot transfer torque backwards to the motor. 

The Main Types of Cam Clutches 

Overrunning clutches can be classified into four main categories, ratcheting, roller, wrap, and wedge cam models. 

• Roller Ramp Cam Clutches

This category of cam clutches is made with cylindrical rollers that are positioned to create a sort of a wedge on the inner and outer flat surface. Anytime that friction is generated between these surfaces and rollers, the rollers wedge as the inner part moves in the direction of the driving shafts. 

• Ratcheting Cam Clutches

These are standard 2-element clutches that utilize one tooth arm for engaging the toothed wheel and freewheels in different directions. These clutches are the commonest in light industrial power tools. 

• Wrap Spring Cam Clutches

These clutches utilize helical springs that help in transmitting torque only in one direction by firmly tightening cylindrical sleeves. They are recommended for low-speed equipment and tools. 

• Wedge Cam Clutches

This cam clutch combines the designs of the other three and offers high torque and overrunning speeds. Instead of using a cylinder-shaped outer member, it has a flat surface and springs that provide a larger area for boosting torque. 

Cam clutches are crucial for industrial machinery, tools, and domestic equipment where the driven and driving shafts need to move at different speeds. To get better performance from your cam clutches, make sure they are bought from top manufacturers, are installed well, and the respective equipment is maintained in top condition.