The transmission, of course, connects to the engine in the exact way that the engine connects to the transmission:

- The piston connects to the rod.

- The rod is connected to the crankshaft.

- The crank is connected to a fly wheel that is connected to a clutch.

- The clutch is connected to the gear-box or transmission.

- The gear-box connects via the driveshaft to the differential. The differential is just another type of gear that transfers the right amount of power to each of the wheels.

Â

- The differential controls the axles. The axles are the connectors between the wheels.

The piston moves the rod, which moves the crankshaft, which moves the flywheel, which (via the clutch and gear-box) moves the driveshaft, which moves the differential, which moves the axles. The axles turn the wheels. The car moves. Voila!

Stop by your mechanic again. If he has a car up in the air on a rack ask him to point out the transmission system to you.

The Clutch

The clutch is a disc. When the pad is released, by the driver releasing the clutch, it lets the engine connect with the transmission. (This occurs automatically in an automatic transmission).

Clutch in = no power transferred

The clutch sits on a spring. As soon as the spring is released, by the driver letting out the clutch pedal, the clutch assembly connects to the fly wheel and thus the engine. When the clutch pedal is pushed in no power can be transferred from the engine to the transmission. If the car is already moving the car will continue to coast with the clutch pushed in, but there is no new transfer of power from the engine, and the driver has less control of the car.

Clutch out = power transferred

When the clutch is engaged (meaning the clutch has been let out by the driver) the engine power is transferred to the transmission. Now the car can move forward, or backwards.

The pad (the clutch) gets worn after a period of time. This pad must be in good condition to properly grip the gears of the gear-box. The length of time the clutch will last without having to be replaced depends on how you use it. Never "ride" the clutch. Riding the clutch means to keep your foot on the clutch while the transmission is in gear. When you shift gears on a manual transmission always let your foot off the clutch as quickly as possible. You may have to "ride" it in first gear to some degree but try not to do so any more than is absolutely necessary to prevent the car from stalling. Get off the clutch as fast as possible when changing up and down all other gears. If you keep your foot on the clutch even lightly there will be friction between the clutch plate and the shaft that goes to the gear-box and the clutch pad will wear out.

Towing automatics

Some very important warnings that can save you a lot of money if your automatic car ever has to get towed are:

- If your car is front wheel drive attach the tow truck only at the front and tow the car only from the front.

- If your car is rear wheel drive tow it only from the rear, backwards.

Here's the reason why:

If you tow a front wheel automatic backwards or a rear wheel drive from the front you are actually causing the transmission to turn as though the car is on, but no transmission fluid is circulating. Doing this for several miles can ruin the transmission. Tow truck drivers do not necessarily know this!

Transferring the Power to the Wheels

We have seen how the drive-train takes the power generated by the engine (via the rod, via the crankshaft, via the clutch) to the gearbox, which magnifies the power received using the gears. This power is now sent to the axles and the wheels to drive the car forwards or backwards.

Types of drive

Cars are front - wheel drive, rear-wheel drive, or four-wheel drive. Front-wheel drive means the power that moves the car forward is directed by the transmission to the front wheels. Rear-wheel drive means the power is directed to the rear wheels. Four-wheel drive means all four wheels are provided with driving power by the transmission.

Differential

In a front-wheel drive car there is a differential on the front axle. A differential is a type of gear that simply distributes the power received by the axle to each of the wheels. It senses how much power to give to each of the wheels. The driving wheels in a car (be it front-wheel, rear-wheel, or four-wheel drive) can turn at different speeds. One of the wheels will spin faster when it needs more power to grip the road, for example when turning or driving over rough ground. The differential essentially "senses the difference" between the speed of spin of the two wheels and will direct more power to the wheel that is spinning faster, as this is the one that is needing more power in that situation.

In a rear-wheel drive the differential is on the rear axle, and it works the same way. A four-wheel drive has both a front-wheel and a back-wheel differential and so can direct power to both the front and the rear wheels.

A front wheel drive in most cases handles better than a rear-wheel drive. It will not spin out as easily and it will allow you to accelerate out of a corner, whereas a rear-wheel drive car will tend to spin out. Certain luxury cars that have a tradition of rear-wheel drive have kept to this tradition. Sophisticated suspension is often used to compensate. It may not entirely overcome the problem especially in adverse weather.