An automatic transmission knows to shift when you're trying to pass another vehicle, going uphill or downhill, or trying to accelerate. However, even though your transmission is automatic, you still have some control over when it shifts. By varying your driving habits and shifting to low gears during appropriate times, you can increase the power and efficiency of your car.
Shifting an Automatic Transmission
The automatic transmission in your car is computer-controlled and programmed to keep the engine running at an optimum RPM (revolutions per minute). Whenever the RPM level increases above the top limit, the transmission automatically shifts into a higher gear so that the engine will turn slower under the same power. When the RPM level decreases beyond the low limit (the engine is turning too slow), the transmission automatically shifts into a lower gear so that the engine will turn faster under the same power. Varying the way you drive can help you control when and how the car shifts gears.
Forcing your automatic transmission to shift into a higher gear is easy. Simply follow these steps:
- Press the gas pedal as hard as you need to in order to get the engine RPM level to increase beyond the transmission's "shift limit." You'll notice this happen when you press the pedal to the floor in order to pass someone or to accelerate quickly onto the highway.
- Once the transmission shifts, you can ease off the gas pedal slightly to keep from going faster than you'd like.
- After your car has gone up the hill or passed another car, allow the transmission to downshift. This will happen automatically when the engine isn't required to work as hard.
Keep in mind that the more often you allow your automatic transmission to naturally select the higher gears, the less fuel that your engine will consume.
You can also force your automatic transmission to downshift into a lower gear. Here's how to do it:
- As you approach a situation where you'd like to downshift, ease off the gas pedal.
- Allow the transmission to shift to a lower gear.
- Keep your speed constant to maintain this gear as long as you would like.
How to Appropriately Use Low Gears
There are several circumstances when you'll need to use the lower gears on your transmission, which are usually labeled with "1," "2," or "L." In every case, improperly using it can damage your transmission, so be careful. Most people never use these lower gears, but you may find yourself in a situation where it is necessary. With an automatic car, you can shift the gears at any time while driving. You do not need to use a clutch like in a manual car.
Towing Heavy Loads
If you are pulling a large boat or you have a truck and the flatbed is loaded down with heavy equipment or supplies, you could damage your transmission if you don't drive in "low gear." This is because your transmission is programmed to operate and shift under the manufactured weight of the vehicle. When you significantly change the weight, it can have adverse effects on the transmission. Using low gear to tow heavy loads ensures that the entire transmission keeps the engine running at higher RPMs in order to handle that heavier load.
Climbing a Steep Incline
If you are in a situation where you're driving up a very steep hill, like taking a tourist drive up on mountain toll road, the automatic transmission can be affected in the same way as though you were towing a heavy load. This is because gravity is pulling back on the vehicle and making the load on the engine much heavier. Use low gear whenever you're driving up a long, steep incline.
Riding Down a Steep Hill
Another technique that not everyone is aware of is using a low gear when driving down a long, steep hill in order to save your brakes. "Riding the brakes" down such a hill can overheat them, and in some cases, it can lead to failure. By switching to low gear and allowing the engine to "brake" for you, you are taking advantage of the compression of the engine pistons to absorb some of that force and slow your vehicle. You'll still need to use the brakes, but you will save them from some of the wear they would ordinarily experience.
Shift When You Want To
Normally, the whole point of an automatic transmission is that, unlike with a manual transmission, the transmission handles the shifting for you. However, there are also circumstances where the normal "gearing" of the transmission doesn't provide enough torque or power for the task at hand. In those cases, you may need to shift the automatic transmission into a lower gear. By understanding when it's appropriate to shift gears with an automatic transmission and how to get your car to shift when you want it to, you'll be a much smarter driver.