i have a simple queation....but need a comprehensive answer...
when u set up a car.......people talk about Differential acceleration and Differential deceleration.......wht does this mean.....wht changes can be done to these to make the car work better in the circuit?????
The differential affects the connected wheels (same axle 2WD - or front to rear if and same axle if 4WD).
The diff can affect the amount of lock between the wheels differently for when the car is under power or coasting.
Power side locking & Coast side locking
Very loosely:
With little or no power side locking, the wheel with least grip will easily spin and let power escape without sending the car forward. With more power side lock the wheels are tightly connected and less engine power is wasted.
One downside of a high power lock is that the car will tend to want to go straight ahead under power rather than turn. Both wheels are pushing the car forward at the same rate. Also, with a high power lock when the tyres do lose grip - you can get snap oversteer (although arguably once the tail is out of line you can use the power again to drive out of the corner - think RWD Rally car).
A low power side will tend to be easy to drive but may well waste power.
Clearly the amount of power lock you want will be affected by the amount of grip at the driven wheels and the speed of the corner.
Coast side lock - if the wheels are tightly connected when coasting, the car will be reluctant to turn into a corner (because the differential effect is negated). However, higher coast side lock can help stability in direction changes. Also, a high coast lock can be prone to putting more heat into the driven tyres. Again it's a compromise.
when a car is turned through a circle the inside rear wheels turn through a shallower circle than outer rear wheel. Therefore some means must be provided so that the inner wheel does not have to rotate at same speed, or do as much as the outer as they follow different paths through circle.
Without this it would be extremely difficult if not impossible to make the car turn at all. The mechanism that allows this to happen is the differential. F1 differentials are highly complex components that are recognised to exert significant influence over a car handling.
Some differentials incorporate a mechanical limited slip facility that helps prevent wheels spin under heavy acceleration by locking the diff. A completly locked diff is ideal for acceleration even in the wet but would have trouble getting around the corners, casuing the car to understeer.
Current f1 cars use electro hydraulic limited slip diffs which allow engineers / drivers to make constant small adjustments i.e. schumi changes the diff at nearly all corners of the circuit via the steering wheel.
The electro hydraulic diff can steer the car by controlling the the differential torque across the axel. The torque disribution differs in different states such as when the car is under acceleration, braking. Under these conditions the limted slip diff can induce yaw or a turning motion that will occur in addition to any steering input made by the driver, or it can resist yaw and enhance stability.
The electro hydraulic diff complies with the FIA's regulations and it is earier for the engineer to set up to provide a given set of charecteristics. The cars on board computer contols a moog valve which regulates the torque going through each output shaft while electronics monitor diff wheel speed.
taken from a excellent book called "The science of formula 1 design" by David Tremayne. I have 3 other books by this author which are clear, very informative and accurate. Additionally david writes the f1 report after each race in the independant newspaper.
Belatti - Differentials are not my area of expertise but I skim-read these links. They may be helpful. I am constantly amazed at the diverse content of Wikipedia. I was just there a few minutes ago looking up Pareto Economic Theory. Interesting stuff
I know a fair bit about the diff and its surely one of the most missunderstood but important parts of the car (any boy racer can tell you how the engine works with a degree of accuracy but get them to explain the diff and they're stumped). I was lucky to have a lego kit at one stage which included a moving engine (in that the wheels drove the engine) and most interestingly a fully working diff attached to the end. It was very interesting to see how the diff worked without all the oil and grease in the way but also portrayed it as a very simple device.
As for LSD (no, not that kind of LSD, Mr Starkey) I know little about except that its a flaw in the design of the Honda CR-V (on the diff between the front and rear of the 4WD system), that it was set up in such a way that on slow, sharp corners the all the wheels were prone to locking. Esspecially multistory car parks where the surface offers alot of friction.
What about a fluid coupling? I think the Land Rover Discovery employs one of these between its front and rear wheels for its 4WD system. Can it be used in place of a normal differential? I wouldn't have thought so as the LR version worked because of the 'slip' in the system, (as the rear wheels don't have as far to travel as the fronts and therefore go slower, the coupling allows them to reduce the output speed without affecting input speed) but it doesn't allow 100% efficiency, so i guess it wouldn't be great for acceleration.
Must be possible to use a fluid coupling in place of a normal diff and the fact Land Rover used it suggests it must have been cheaper than a standard diff or have some crucial advantage.
Murphy's 9th Law of Technology:
Tell a man there are 300 million stars in the universe and he'll believe you. Tell him a bench has wet paint on it and he'll have to touch to be sure.
Guess differential acceleration lets our outer wheel acc faster than the inner wheel , which give u an oversteering effect , and diff deceleration is used to compensate that , . well u can use this to get good exit in fast corners and good entry into the corners . So i guess this bit of info would help u to get some idea about it , so happy setting up ur car ..
