clutch plate - rivets

The sketch in the previous post shows a couple of rivets. But why do they use rivets?

Especially these who connect the friction material with the other parts of the clutch. Because this is the place where power transmit from one part to another.

If the clutch is in function, so all parts are connected by a large force, the frition plates are pushed between the flywheel and the pressure group. But a part of the clutch plate is pushed between the two friction plates. So there is a friction force between the different parts of the clutch plate. Rivets are necessary to keep the clutch plate together if there is no connection.

Another aspect is that it is useless to disconnect the friction plates from the clutcht plate. If the friction plates are destroyed, the whole clutch is probably at the end of his life.
Its also a very easy connection, no turning tools are required

clutch plate - sketch

connection primary shaft - clutch plate

The connection between these two parts needs a radical fixation, but a axial freedom, but still be able to translate the power from one part to the other.

A good solution is a splined shaft.

It will be a 21x24 splined shaft

the properties: z= 34 (the last unvisible column)

more info: tabellenboek voor metaaltechniek (E31 - p 212)

radius primary shaft

Another imporant part of the clutch is the primary shaft. It's the link between clutch and gearbox.

theoretical the torque produced by the motor is the same torque on the disc plate and the same as on the primary shaft.

calculation:
d= 11,65mm

the real situation: 24 mm

or there is something wrong in the calculations (probably) or there are some properties of the gearbox that influence the radius.

mass flywheel

The mass of the flywheel depends on the motor and the mass of the car.
The calculation of the mass is a part of the engine. A lot of people doing flywheel-tuning. They take weight off the flywheel, the mass declines and the car becomes a little faster?

If the mass declines too much, you will never be able to drive the car.

flywheel - bolts

The main function of the flywheel is keep the motor spinning. It has a weight of 12 kilo. The total weight of the clutch (housing inclusive) is about 19,5kg...

Such a mass will cause a lot of centrifugal force. First a calculation of myself followed by a comparison with the real information.

What's the radius of a bolf if you can use 8?

The centrifugal force is calculated in the mass center. If you count the whole flywheel the mass center is in de middle. If there are 8 bolts, you can devide the flywheel in 8 equal parts. The distance from the center to de mass center is about 200mm.

F(c) = 14 808N (for 1 bolt)

The torque causes a force perpendicular to the radius: F(t) = 1280N

F(tot) = 14 863N

The max shear of a 12.9 bolt is 1080Mpa. (www.werktuigbouw.nl)

the safety factor for dynamic loads: v= 3...6

for the calculation: v=5

result: r= 4,68

this results in 8 bolts: ISO 4017 - M10 - 12.9

If you use bolts with another classe, you will become a larger radius.

more info: tabellenboekje voor metaaltechniek

the car - volvo 240

The clutch I will discus is one of a volvo 240 (1987). It's already an older car, but the principles are the same.
The car is a rear wheel drive one.

properties:
volvo 240 '87
motorcode: B230K (Benzine, 2,3l)
HP: 85kW/116Hp @ 5100 tpm
torque: 192Nm @ 3000 tpm