The purpose of a car's transmission is to take the power that is produced by the engine and drive the wheels. The engine's crankshaft spins at a certain speed, depending on throttle position. The transmission can either reduce or increase that speed based on a selection of gears. The transmission then turns the driveshaft, which then turns the wheels.
Internal combustion engines produce most of their power over a narrow range. Therefore it is necessary to have different gear ratios to allow power over a wider range of vehicle speeds. Transmissions allow cars to have good power and good fuel efficiency at the same time. A car without one would perform very poorly or use a very large amount of gas.
The transmission is a rather complex piece of machinery, typically having anywhere from four to six speeds, and can be either manually or automatically controlled. Automatic transmissions are more complex, as these need more parts in order to shift the transmission. Manual transmissions are more simple, as the shifting is handled by the driver. Either type is prone to problems, so the more complex it is, the more likely a piece of equipment will have issues, and transmissions are no exception.
Automatic transmissions are the most popular due to their convenience. Unfortunately, automatics are much more complex than manual transmissions, and therefore are much more prone to having issues. A good transmission should last the expected lifetime of a vehicle, however problems may still arise. Transmission issues are usually easy to notice, thanks to the fact that the transmission is directly connected to the powertrain.
Because of this, a problem with the transmission can usually be heard or felt. Symptoms of problems in an automatic transmission can include such things as slow or delayed shifting, jerking, hesitation on acceleration, grinding or thumping noises, excessive vibration, whining, reduced power and engine overheating. Other symptoms can be more obvious. These are such things as a car's failure to move or transmission fluid loss, which can be seen as reddish stains on the ground underneath the car.
Manual transmissions tend to have fewer issues, but these can still occur, especially in older or heavily-driven vehicles. Symptoms for manual transmissions can include failure to shift into a gear (or multiple gears), clutch not disengaging, and odd noises such as grinding or whining. Excessive vibration, loss of fluid (normally brownish color), engine overheating and failure of the vehicle to move, despite the fact that the engine is running.
If any of these issues are encountered, it is very important not to keep driving the vehicle. If you do drive it, further transmission damage and engine damage can occur. The vehicle should be taken in to an auto repair shop as soon as possible. Be sure to note all issues encountered, and describe the problems in detail to the mechanic.
Describe any noises and any odd behavior while driving. Be sure to be thorough in your description, as this saves time in diagnosing the problem which can save you money. Transmission repair is complex and can be costly. However, by acting in a timely manner and being observant you can save money.
