driving the wheels...

[drunken monkey]

hey-ya...
how does the engine drive the wheels?
i mean, what is the process of transferring the turn of the engine to turning the wheels?

i ask this cos well, i have built a few car models in 1/24 and have noticed that while the majority of the cars have 'straight' arms driving the wheels, the ferrari 288 GTO have arms that are at an angle.
um..
what i mean, is, a normal car's arms are II--[engine]--II
where-as in the ferrari, the arms are angled to the engine.

make sense?

[Reed]

it depends on if its front or rear or all wheel drive.

fwd - you have an engine usually placed horizontally to the direction you drive and there is a trans-axel attached to one side and a differential is attached to the back of that. then you have, on the side of the diff that faces away from the engine, a cv shaft that then attaches to the wheel. on the other side of the diff you have an intermediat shaft that connects to another cv shaft. the intermediat shaft basically allows the cv shafts to be equal lenghts.

this is basically the same setup as a mid engine rear whell drive ecxept the cv shafts connect directly to the diff without an intermediat shaft and the engine can be setup longitudinally as in most supercars such as the enzo and bugatti veyron.

rwd - the engine is set up in the front longitudinally with a transmission on the back and a driveshaft on the back of that connected in the rear of the car to a diff and on either side of the diff there are shafts that connect to the wheels.

awd - can be set up with the engine either longitudinally as in a wrx or horizontally as in a talon or eclipse.

longitudinally is set up like a rwd except there is another differential in the front on the tranny with shafts on either side fo the diff going to the wheels.

horizontally, well im not exactly sure how they do this so im not going to speculate and if anyone has any corrections or additions please add them.

[SaabJohan]

The gearbox/differential from Ferraris F1 car from year 2000, the gearbox is of transaxle type, has seven gears and is directly connected to the engine



From the differential the two driveshafts are driven seen here in between the suspension arms on the Ferrari F1 car



A driveshaft



Wheel hub



Upright assembly (note the hub in the upright assembly)



and CV Joint

[drunken monkey]

ahhhh.....
so the drive shafts are 'connected' to the engine with some kinda bearing
so that even if they (the arms )are not perpendicular to the engine, the resulting turn of the wheel is.

right?

and i'm assuming that the differentials and bearings 'in the way' is the reason why there is 'loss' of power from engine to wheels...

thanks guys....

[Reed]

not so much power loss in the bearings as in the diff but definately not as much in the diff as in the transmission/transaxel.

[SaabJohan]

The largest of the powerloss is probably caused by the friction between the gears.

The powerloss in an transmission is what makes it hot as the energy is lost as friction heat.

The Formula One gearbox on the image above loses about 5% of the engine power on the way to the wheels. In normal transmission the loss is higher, the F1 gearbox is likely more efficient due to its straight cut gear which also makes it noisy.

There was one part missing in the pictures above; the clutch which can look like this:



The parts shown on the pictures above are racing parts, the principle is however the same.

In construction equipment like excavators the power transfer is often done with hydraulics instead, the engine powers a hydraulic pump which powers small hydraulic motors at the wheel hubs and in diesel locomotives the engine usually powers a generator which delivers electricity to electric motors which drives the wheels.

[Reed]

I'm under the impression that in f1 cars they use a system that cuts ignition for a fraction of a second while the sequential gearbox shifts.

Is there a clutch pedal or is the clutch automatically disengaged while the driver shifts with the padles?

[SaabJohan]

If you look at the picture of the Ferrari gearbox you can see the sequential shifter on the side of the gearbox. It is driven by a hydraulic rotational actuator controlled by a MOOG servovalve. The clutch itself which is of pull type rather than the more common push type is also controlled by an actuator controlled by another servovalve.

When shifting gears this is done with full throttle without using the clutch (it's possible that they cut the ignition but I'm not sure if they do that). This is possible because of that "dogs" are used instead of synchros. The clutch is only used when driving away from a pitstop or in the start of the race, the cars have no clutch pedal, instead they use a paddle on the steering wheel so even that launch systems are forbidden you just use the paddle and the car basicly launches itself but earlier the driver just pushed a button and didn't have to do anything until it was time to brake in the first corner, that is if we exclude steering of course.

I believe that I read an explaination earlier from Jaguar I believe it was, exactly how to launch the car.

During a start the friction material (carbon-carbon) in the clutch is heated to around 1000 degrees celsius. Because of the high temperatures the metal parts in the clutch is made from forged titanium rather than aluminum. Because of the high temperature a restart take very hard on the clutch aswell as the engine which can easily overheat if it doesn't get any cooling air (cooling fans are forbidden since they have been used to increase downforce).

[Reed]

are those gold things on the suspension peices the heat sticker things.