- Overdrive signifies top gear/gears in a car that enable the engine to render better performance and fuel consumption.
- In the automatic transmission, the overdrive is permanently on, and it can be turned off by pressing a button installed on the gear shifter.
- When you turn overdrive off, a sign of O/D Off illuminates your car’s dashboard.
- Overdrive mode is recommended to be used on highways and plane roads with less traffic where you can relatively maintain a speed of 60mph or above.
- Improper usage of overdrive may cause the failure of transmission.
What is Overdrive?
Overdrive is a car-operational system that allows you to attain more performance and experience optimized fuel economy. Engineer William B. Barnes is credited with the design of this marvelous invention. To understand the function of overdrive, it is important to understand its background first.
Generally, the third gear used to be a direct drive. In direct drive, the input shaft, through which the engine is connected to the transmission, spins at the same speed as the output shaft, which further connects the transmission to the wheels.
By having the third gear as direct drive, earlier cars would have to exhaust their full engine power while driving on highways. Resultantly they would not only waste a lot of fuel but also cause disturbance to the passengers and drivers by making a lot of noise.
This problem was solved by introducing some modifications to the car’s transmission. First, an additional gearing unit was attached to the back of the car’s gearbox box and was named 4th gear or overdrive.
Benefits of Using Overdrive
Reduces Engine’s Load
The overdrive functionality reduces the engine’s load, thereby lowering the wear & tear of the engine and transmission box.
Less Fuel Consumption
Gas prices are now about 10 times higher than their average level over the past decade. Since the continuous hike in gas prices increases the inflation rate, it is better to adopt fuel consumption techniques. When an engine rides with the overdrive gear, it will only require 1/3 less fuel. As a result, you can save a lot of fuel costs. It will also reduce gas emissions which is beneficial for our planet.
Increasing Engine Life
The overdrive uses only a few revolutions compared to lower gears. Therefore, less energy is required to complete the route, extending the engine life and giving less stress to your vehicle. In addition, other parts like the water pump, generator smog pump, A/C compressor, and alternator turn at lower RPMs when the engine uses overdrive.
According to recent research, vehicles with overdrive deliver 30% higher RMP than the traditional engine’s RPM . Furthermore, a paper published in the Society of Automotive Engineers, Inc. concluded the application of overdriven gear (28-30%) is known to give considerable gains in fuel consumption and an imperative amount of reductions in the noise level .
No More Noise and Clattering
When your engine moves at lower RPMs, it will produce zero to little noise and a clattering sound. It lowers the noise, vibration, and harshness (NVH). Hence, you’ll experience a more relaxing and untroubled trip. If you’ve big vehicles carrying strong engines like SUVs or trucks, the overdrive feature will keep your ride smoother and more pleasant on the highway.
How to Turn Overdrive On
In most automatic cars, the overdrive button is found on the gear shifter. The overdrive mode is permanently active in these cars, and you turn it off by pressing the overdrive button.
How to Use Overdrive Mode for Different Road Conditions
Overdrive mode is recommended when driving on highways or roads with less traffic. The only requirement is that you have possibilities in which you can maintain a speed of 50mph or above. The on-road situations where the overdrive mode should not be used are:
- When your car is climbing up long, steep hills.
- When you are on a road trip and want to drive slow to enjoy the trip.
- When you are on the road with heavy traffic.
- When you want to overtake a car.
- When you are towing some heavy load.
Damages Caused by Improper Use of Overdrive
Although the overdrive feature in automatic cars helps you utilize a complete transmission range, improper use of O/D mode, especially in the cases mentioned below, may trigger severe issues.
- Towing a trailer or large loads
- Traveling at less than 50 mph
- Propelling uphill
- Driving in a town or city
- Driving in terrible weather conditions
However, the final price depends on the make, car model, local area, and extent of damage faced by the transmission.