Your transmission is the gear box that converts the rotating power in your engine’s output to usable speed and torque to move your axles, wheels and vehicle. The transmission is a critical component, because the engines in modern cars operate anywhere from 600RPM (revolutions per minute) to 7000RPM. Your car’s wheels, on the other hand, rotate from 0RPM to 1800 RPM, so the transmission steps down the speed of rotation and uses your engine’s high output to generate enough high torque to move the car at low speeds, and still be able to function for highway travel.
Your transmission is made up of many interconnected moving parts and those of us without a mechanic’s license may find the complexity quite confusing. Read on for some fundamentals that can help you learn to get your transmission parts replaced or repaired in no time.
Transmission Basic Anatomy
Transmissions are typically housed in a cast iron or light weight aluminum case, the latter being more common in smaller and passenger cars. There is a mainshaft that passes outside the case, with one side pointing towards engine, and the opposite towards the rear axle of your vehicle, for a rear wheel drive vehicle. In a front wheel drive layout, the shafts are mounted transaxially. The mainshaft is suspended by bearings, and the gears and clutches are supported by the mainshaft, free to turn independently except when clutches are engaged.
Clutches are the most heard of transmission part, and their essential function may give a clue as to why that is the case. The clutch uses a sliding friction disc mechanism to engage two rotating shafts in unison or disengage them allowing for different rates of rotation. Friction discs press against your clutch’s flywheel mechanism using springs, and this allows your clutch to engage a second shaft.
Transmission Basic Types
Manual transmissions can be unsynchronized, wherein the speed of the free-spinning gear sets must be synchronized by the operator to avoid damaged gears due to teeth clashing together. More common nowadays are those manual transmissions that are synchronized. Completely non synchronous transmissions are commonly used on commercial and military vehicles, but the most common basic transmission in the US is the automatic variety.
Automatic transmissions select appropriate ratios for gear shifting without you having to intervene in the process. Because they select gears with hydraulics and a fluid flywheel instead of a clutch, automatic transmissions are the easiest to operate. Modern computerized automatic transmissions maximize fuel efficiency and regulate all of the internal gear switching procedures in accordance with the vehicle’s current operating conditions.
An important difference in manual and automatic transmissions lies in how the transmissions’ parts work. With manual transmissions, your changes cause gears to move, sliding along the shaft until the correct gears for the selected ratio in place. An automatic transmission has a set of “planetary” gears that do not physically shift position, arranged radially around a center “sun gear.” By applying power to different gears in the system and locking the motion the various parts together, the output shaft can rotate at different speeds.
Replacement Transmission Auto Parts
Getting a broken transmission repaired can be an ordeal. Few parts are accessible from the outside, so you’ll most likely find that most mechanics will tell you your options are limited to replacement. With your newfound automatic transmission parts knowledge, however, it’s a very good idea to ask them what specific parts have failed. The mechanic should be able to give you a diagnostic report using a computer or performance check, with this, you can locate your parts yourself. Doing it this way, you will avoid the higher costs that you’ll face by letting your mechanics take care of the entire process themselves.
