63 Tiger Cub - Clutch

Will, Adam, Robert, and Jack

What is a clutch?

• A clutch is a device used in machines to transmit power from the engine to the transmission

• It can be engaged to allow the engine and transmission to spin at the same speed or disengaged to allow them to spin at different speeds (thus allowing the rider to shift gears)

• Wet vs. dry clutch?

Why do we need a clutch?

• The clutch allows for a smoother shift from gear to gear

• Without a clutch the transmission would wear down over time

• Without a clutch, the only way to stop the wheels from spinning would be to turn off the engine (because otherwise whenever the engine spins the wheels would too)

Clutch Parts

Clutch Parts

Backing Plate

• Backing plate, rebound rubber, drive rubber, spider, lock washer, centre, centre driving cup, backing plate pin, sprocket bearing ball, sprocket bearing ring

Sprocket and Housing

• Double sprockets

Driven Plates

• Steel• Lugs on inside• Engage with the

engine

Driving Plates

• Pads = cork• Lugs on outside• Engage with the

transmission

Pressure Plate• Presses plates together to engage clutch• Pushed up by clutch operating rod to

disengage clutch and allow rider to shift

Spring Cups

Pressure Springs

• Press on pressure plate to engage clutch

Pressure Spring Nuts

Sprocket and Primary Chain

• Why double chain?– Innovation double

chain is more durable, single chain caused the sprockets to wear down/break

Clutch Lever

Clutch Cable

Clutch Operating Rod

How It Works

• When the clutch is engaged, the driven and driving plates are pressed together by the pressure plate and springs and spin at the same speed

• When the clutch lever is pulled, the clutch operating rod pushes up on the pressure plate, disengaging the clutch and allowing the engine and transmission to spin at different speeds, thus allowing the rider to shift gears

Friction - Why multiple plates?

• Having multiple plates increases the friction, thus reducing the slippage

• The greater the friction, the greater the torque that the clutch can handle without slipping

How much force is applied by the springs?

• Gear ratio: 19/48• Length of spring: 1.53 in. = .1275 ft.• Length of spring after 20 lbs. applied = 1.324

in. = .1103 ft. • # of surfaces touching = 7• Coefficient of friction = 0.8 (cork on steel)• Diameter of clutch = 5.33 in. = .444 ft. • Clutch slips @ 50 ft.lbs.

How much force is applied by the springs?

• F = kx (spring)• F = uN (friction)• T = rF (torque)• Given a torque, we found compression in the

springs• If we assume a certain amount of compression

in the spring, we can find any torque