| -- End Ad Box ---> | | | | have to shift the gears yourself, usually with a stick |
| The drive train serves two functions: it transmits | | | | located on your console and the clutch pedal. If you |
| power from the engine to the drive wheels, and it | | | | have an automatic transmission, the mechanism |
| varies the amount of torque. "Power" is the rate or | | | | changes without any help from you. This is |
| speed at which work is performed. "Torque" is | | | | accomplished through a system that works by oil |
| turning or twisting force. Multiple ratio gearboxes are | | | | pressure. Each shift of the gears is controlled by a |
| necessary because the engine delivers its maximum | | | | shift valve; the gears shift change depending on |
| power at certain speeds, or RPM (Rotations Per | | | | speed, the road, and load conditions. |
| Minute). In order to use the same engine RPM's at | | | | Another basic component of all drive trains is some |
| different road speeds, it is necessary to change the | | | | form of a clutch. it allows the engine to continue |
| "Gear Ratio" between the engine and the drive | | | | rotating while the gears and wheels are stationary. |
| wheels. Just like a bicycle, the car has to switch | | | | Automatic transmission cars use a "torque converter" |
| gears in order to move at a wide range of speeds. | | | | in lieu of a clutch. |
| Unlike your bicycle, the car's drivetrain also has to | | | | The last component in the drive train is the axle. In a |
| allow you to back up. (Well, you could push it | | | | rear wheel drive car the axle is in the rear. Engine |
| backwards if you ate your Wheaties) | | | | power is transmitted from the transmission to the |
| There are actually two sets of gears in the drive | | | | axle via the drive shaft. The drive shaft is basically a |
| train; the transmission and the differential. The | | | | metal tube with joints on each end called universal |
| transmission allows the gear ratio to be adjusted, and | | | | joints. These joints allow the tube to move in relation |
| the differential lets the drive wheels turn at different | | | | to the suspension and keep power flowing to the |
| speeds. | | | | rear. In front wheel drive cars the axle is integrated |
| Manual transmissions usually have four or five speeds, | | | | into the transmission thus the term transaxle. |
| and often have "overdrive", which means that the | | | | >From the back of the engine to where the rubber |
| output shaft can turn faster than the input shaft for | | | | meets the road, the drive train encompasses one of |
| fuel economy on the highway. Some use an electric | | | | the most complicated systems of your car. Some |
| clutch and a switch that controls whether the | | | | people say looking at a transmission "makes their |
| overdrive is engaged or not. An interesting | | | | brain hurt". |
| development on a few cars is the "clutchless" manual | | | | The above information is directly from the Auto |
| transmission, which uses a stick shift and an | | | | Insight program, which you can buy online from |
| automatic electric clutch. Speed and position sensors, | | | | Common Problems: |
| mini computers, and throttle controls keep the engine | | | | - Manual transmissions suffer from wear mainly in the |
| from over-revving when the driver shifts gears. As | | | | synchronizers. The synchronizers make shifting easier |
| with many automotive "inventions", this is an old idea, | | | | and help to prevent gear clash. Over time the |
| which may now reach feasibility due to the computer | | | | synchronizers, which are made of brass, can wear |
| revolution. | | | | out causing hard shifting and grinding. |
| Automatic transmissions commonly use three | | | | - Automatic transmissions can also wear out, causing |
| forward gears to blend speed and torque. In the | | | | slipping and uneven shifting patterns. Universal joints |
| case of a three-speed transmission, first gear delivers | | | | can wear and cause vibrations while driving. Many |
| maximum torque and minimum speed for starting. | | | | newer universal joints are sealed and cannot be |
| Second gear offers medium torque and speed for | | | | lubricated, leaving replacement as the only option. |
| acceleration and hill climbing. Third gear allows | | | | Preventive Maintenance: |
| maximum speed with minimum torque for highway | | | | - Change the fluid in your transmission at |
| travel. A reverse gear permits backward movement. | | | | recommended intervals. Your owners manual will give |
| A transmission is a speed and power-changing device | | | | you a time schedule in miles and or months. If you |
| installed at some point between the engine and | | | | tow a boat or trailer be prepared to change the fluid |
| driving wheels of a vehicle. It provides a means for | | | | even sooner. Most owners manuals will give you |
| changing the ratio between engine RPM (Revolutions | | | | recommend intervals for severe use like towing or |
| Per Minute) and driving wheel RPM to best meet | | | | off-road use. |
| each particular driving situation. | | | | - Do not "ride" the clutch if you have a manual |
| Some types of drive train layouts use a "Transaxle", | | | | transmission. Learn to release the clutch in a smooth |
| which is simply a combination of the transmission and | | | | motion without revving the engine too much. Revving |
| the differential. These are usually found on front | | | | the engine too much while pulling out can cause |
| wheel drive cars, but are also used on mid- and | | | | premature wear on the clutch. |
| rear-engine cars. Some exotic cars have their engine | | | | - If you do tow a boat or trailer, consider getting a |
| in the front, and a transaxle in the rear of the car for | | | | transmission cooler for your automatic transmission. |
| better weight balance. | | | | Temperatures can approach the boiling point in |
| Torque is derived from power. The amount of | | | | severe conditions. Most newer trucks come equipped |
| torque obtainable from a source of power is | | | | with transmission coolers if sold with a towing |
| proportional to the distance from the center of | | | | package. |
| rotation at which it is applied. It is logical, then, that if | | | | - Make sure your universal joint is lubricated at oil |
| we have a shaft (in this case, the crankshaft) | | | | changes if they are the type, which can be lubricated. |
| rotating at any given speed, we can put gears of | | | | When replacing universal joints try to find |
| different sizes on the shaft and obtain different | | | | replacements with lubrication fittings so you can |
| results. If we put a large gear on the shaft, we will | | | | lubricate in the future. |
| get more speed and less power at the rim than with | | | | - If you have a front wheel drive car, avoid applying |
| a small gear. If we place another shaft parallel to our | | | | the gas to the floor while the wheels are turned at |
| driving shaft and install gears on it in line with those | | | | full lock. This puts stress on the universals and can |
| on the driving shaft, we can obtain almost any | | | | cause premature failure. This can happen when stuck |
| desired combination of speed or power within the | | | | in the snow and trying to get out. |
| limits of the engine's ability. That is exactly what an | | | | What to discuss with your mechanic: |
| automobile transmission does by means of gears and | | | | - If you are noticing a vibration in the car while |
| other devices. | | | | driving, make sure to describe when it happens. While |
| There are two types of transmissions; manual and | | | | accelerating? braking? maintaining speed? when |
| automatic. If you have a manual transmission, you | | | | turning? |