January 29, 2021
This component transfers the energy generated by the engine to the wheels. Generally the engine has an RPM (rotations per minute) range from idling to red-lining. The transmission efficiently switches that fixed RPM range to a much larger one, utilizing a series of gears that sequentially increase the rotational force delivered from the engine to the wheels, allowing the vehicle to go faster and faster with each gear shift.
There are three types of transmissions. The original ‘Manual’ or stick-shift transmission, the no-manual shifting required ‘Automatic’ transmissions, and the latest ‘Continuously Variable’ transmission, which won’t jerk and mess up your lipstick application.
The manual-shift transmission is the grand-daddy, original. And preferred by drivers who want greater control over how their vehicle responds to their needs. A manual transmission puts all the control, and potential to destroy the car, in the hands and feet of the driver.
The basics are: the driver of the vehicle uses their left foot to physically depress a third pedal on the floor next to the brake, which disengages the transmission from the engine using a friction clutch. During this action, the driver moves the gear shifter, (a lever, protruding from the floor or steering column,) through a series of ‘gear’ positions labeled 1, 2, 3, 4, and R (for reverse.)
1st gear transfers the least amount of power to the wheels, allowing the vehicle to start its forward motion. When the engine reaches the top of it’s RPM range, the driver depresses the ‘clutch’ pedal, and physically shifts the transmission into the next highest gear, all the way up to 4, or 5, or higher, depending on the transmission.
Manual, also referred to as ‘Standard’ transmissions have the least moving part, and thus usually a longer life. The also commonly offer better mileage, because the driver can disengage the engine completely, in the case of a very long downhill stretch of highway. And, they’re cheaper.
A few popular terms related to shifting a manual transmission include: “popping the clutch”, which refers to revving up the engine and engaging the transmission quickly, forcing the drivetrain to jump into gear and propel the car forward at a much faster initial rate; “riding the clutch”, where the driver keeps the clutch pedal slightly depressed causing slippage in the transmission, (which is a bad thing); and finally, “downshifting”, which is forcing the transmission down a gear while revving up the engine to gain extra power or speed.
A Fraser fun fact, it is possible to shift a manual transmission without the use of the clutch. It is an art form, but in some transmission, there is a sweet-spot where the gears line up perfectly for the transition from the previous gear to the next. Driving enthusiasts, in-tune with their vehicle, can make those shifts with no clutch and no grinding.
The automatic transmission, as its name indicates, takes the manual shifting control away from the driver, and utilizes a sophisticated set of mechanical timing and a complex torque converter to shift gears and propel the vehicle forward smoothly through acceleration.
Automatic transmissions still have shifting levers on the steering column or the floor. Some have push-buttons. Most are labeled P, for park, N for neutral, R for reverse, D for drive, and often there are other options like OD for overdrive, and 3, 2, and 1, which give the driver the option of forcing the automatic transmission to stay in a particular gear, like in the circumstance of driving on snow or ice.
Automatic transmissions became the choice of the average driver because they are far easier to use, and perform extremely well at low speeds, like being stuck in traffic. If you’ve ever been in a construction zone, driving your stick-shift, it’s a lot of tedious pedal pushing to move a few feet a time.
Automatic transmissions still can’t match the performance of a manual transmission, but they’re coming closer each year, with computer controlled responsiveness and as many as ten speeds (gears) to work with.
Most seasoned drivers know the difference between a manual and automatic transmission, but make a scrunchy face when asked about a CVT (continuously variable transmission). In a nutshell, the CVT is the next evolution of the transmission. It commonly utilizes thick v-shaped belts that ride between constantly expanding and contracting pullies. This system produces and infinite range of torque ratios with no gears. It provides a continuously smooth acceleration experience, weirdly absent of the familiar gear-shifting-jolt.
There is a fourth type of transmission called the Dual-Clutch Transmission or the semi-automatic transmission, and it is a hybrid between a traditional standard transmission and an automatic.
This iteration is designed with two sets of clutches for the odd and even gears. It uses a system of pneumatic actuators that can change the gears incredibly fast. This kind of transmission is most common on performance vehicles, and is identifiable by the existence of ‘paddle’ shifters on the steering wheel, which allows the driver to focus on the road without having to move one hand to a shifter on the floor. Of course, with the extreme performance, comes extreme complexity, and the propensity for costly repairs should something go awry.
If you’re thinking about upgrading your car, Call Fraser for a world-class remanufactured engine or transmission.
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