Welcome to our discussion of the centrifugal clutch vs. torque converter. This article centers on teaching you what each one is.
We will also discuss situations in which these mechanisms work best.
What is a Centrifugal Clutch?
This centrifugal clutch uses centrifugal force to connect the driving shaft of the engine with the transmission shaft. You can find this mechanism between the flywheel of the engine and the transmission.
The primary purpose of a centrifugal clutch is to provide a connection between the engine shaft with the transmission. This type of clutch is best for high speeds.
The clutch works in a way that is entirely dependent upon the centrifugal force the driving mechanism creates; such as the motor or engine. The centrifugal force then engages the clutch with the driving shaft.
Once the engine begins turning, a centrifugal force is produced, which makes the sliding shoes go outward. The special lining-the friction lining- becomes connected to the inside of the drum and begins to move.
Because the drum directly connects to the driving shaft, the power is sent from the engine shaft to the transmission and then finally the load.
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Parts of a Centrifugal Clutch
To understand a centrifugal clutch fully, let us examine the components that go into it. Understanding the elements of the centrifugal clutch will also be helpful if you plan on repairing your own. Or learning how to do so in the future.
- The shoes: The shoes are the sliding variety, and they slide into the guideways. They are made of friction lining on end, and this lining comes into contact with the drum when it is engaged.
- The Spring: The spring is utilized in disengaging the clutch during times when the engine turns at a low speed.
- Guides/Spider: Spiders are found on the engine or motor shaft. They are spaced equally apart. This means that if they are four guides, each one shall be separated from the other with a 90-degree angle. The sliding shoes are stored between the guides, and each guide houses a spring.
- Friction Lining: Friction lining can be found on the outside of the outer surface — this aids in making it grip the inner part of the drum.
- The Drum: The drum of the centrifugal clutch serves as a sort of housing in which all parts of the clutch, including springs, guides, sliding shoes, etc. are stored. This is connected to the driving shaft of the transmission, belt, or chains.
Check out this diagram of a centrifugal clutch. This image was from Engineeringclicks.com
How Does It Work?
First, the engine rotates. The inner workings of the centrifugal clutch begin to turn also, but the drum stays put. No power is transmitted.
At lower speed, the centrifugal force being produced is not powerful enough to overtake the force of the spring. Therefore, the clutch stays disengaged. As speed goes up, the centrifugal force does also and becomes more powerful than the spring force.
As this force becomes more significant than that of the spring, the sliding shoes are allowed to move in an outward direction against the spring and engage with the drum’s inner surface.
The drum will begin to rotate and will transfer the rotating power from the engine to the transmission’s driving shaft. When the load on the engine becomes higher, the speed goes down, and the clutch becomes disengaged.
We realize it can be a bit hard to put all this together. Please check out this video here to see it in action.
Applications Best Suited for Centrifugal Clutch
As we mentioned, high speeds are best for a centrifugal clutch. You will find it in machines that have to move at high speeds.
Some examples are a chainsaw, go-kart, lawnmower, and minibike, to name a few. Boats also make use of this style of a clutch. This is because it keeps the engine going even when it stalls and helps disengage loads during the processes of idling and starting.
It is advantageous because it is not very pricey, is automatic and does not require a control mechanism, and is also rather simple and easy to maintain compared to other clutches.
What is a Torque Converter?
If you are driving a vehicle with an automatic transmission, as many cars in the USA are, then you will require a torque converter so that your car can come to a full and complete stop.
Vehicles featuring an automatic transmission require a way to have the engine spin while the wheels and gears contained inside the transmission come to a halt.
Manual transmission vehicles make use of a clutch for this to happen. The engine is entirely disconnected from the transmission in this situation. Meanwhile, torque converters are used in automatic-transmission vehicles.
A torque converter is just one type of fluid coupling which lets the engine turn independent of the transmission.
Should the engine be turning slow, such as periods of idling in a parking space or drive-thru window, the amount of torque transmitted through the torque converter is minimal.
Therefore, it requires only a small amount of pressure to hold the brake and keep the car steady.
Imagine a person steps on the gas pedal while the car is stopped. Now they wish to stop the car once more.
It becomes necessary to step harder on the brake in order to prevent the car from moving. Why is this?
It is because when you apply pressure to the gas pedal, the engine gains speed. It transmits more fluid to the torque converter. This sends more torque to the wheels.
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Check out this helpful video here to learn more.
Parts of a Torque Converter
There are four main parts to a torque converter. They are the pump, turbine, stator, and transmission fluid.
How Does It Work?
Like the centrifugal clutch, the torque converter also features housing. In this case, the housing is attached to the flywheel of the engine via a bolt.
There are also fins that are part of the pump of the torque converter. They are attached to the converter’s housing and thus turn at the same speed as the engine.
The pump inside of the torque converter operates with centrifugal force. It is a centrifugal pump. As the pump spins, fluid goes to the outside, similar to how a washing machine throws water and clothing to the tub of the machine.
As a result of this phenomenon, a vacuum is created, and more fluid is pulled to the center.
This fluid then makes its way to the turbine blades. This is connected to the transmission. The turbine makes the transmission spin, which results in your car moving.
The turbine blades feature a curve. The fluid enters from outside of the turbine. Thanks to the curved blades, it changes direction before leaving the center of the turbine, and the change in direction results in the turbine spinning.
The fluid exits at the center of the turbine. It is moving in a different direction than when it first entered the turbine from the outside.
This is where the stator comes in.
The stator is at the dead center of the torque converter. The purpose of the stator is to redirect fluid that is returning from the turbine. It sends it away before it touches the pump again.
This results in a more efficient torque converter.
More About the Stator
The stator’s blade design is aggressive and is designed to do a specific job. It is designed to reverse the transmission fluid direction.
Inside the stator, a one-way clutch provides a connection from the stator to a fixed shaft. This fixed shaft is in the transmission. Thanks to this arrangement, the stator is not made to spin with the fluid.
Instead, it spins only in the opposite direction. This forced the fluid to change direction when it comes into contact with the blades of the stator.
Applications Best Suited for Torque Converters
As you have already guessed, automatic transmissions are best for torque converters. You will also find it in industry, mostly being used in power transmissions. You see such transmissions on machines like conveyor belts, drill rigs, and forklifts.
Even heavy construction equipment uses this mechanism, as well as locomotives. Marine propulsion is another popular application for torque converters.
The torque converter has lesser fuel efficiency than that of a vehicle equipped with a manual transmission. This is because the transmission does not move at the same speed as the engine. As a result, power is wasted.
Compare and contrast any manual transmission car with the same model featuring an automatic. You will see the difference in gas mileage.
In conclusion, we can see the advantages and disadvantages of both. Each is great when used in the proper application.
I hope that you were able to learn the differences between these two mechanisms. No matter your purpose for learning, we hope it will be helpful for you in the future.