Going into overdrive isn’t just a feature that action heroes implement during exciting car chase scenes. Most modern automatic vehicles are equipped with an overdrive system due to the many benefits that go into overdrive can provide. In fact, if you have a vehicle with an automatic transmission, you probably use the overdrive feature all the time without even realizing it. Consult this complete overview of the automatic overdrive system to learn more about what this system is, how it works, and what advantages it provides.
What Is an Automatic Overdrive System
An automatic overdrive system is a type of gear-reduction transmission system that allows the engine to operate with lower revolutions per minute (RPM) while maintaining a given cruising speed. When the driver switches the system on, the automatic transmission can shift into overdrive mode upon reaching a certain speed—typically around 40 miles per hour or higher depending on the load. The overdrive gear is generally the highest gear in the transmission. If the system is off, the automatic transmission will only have the capability to shift into lower gears.
The term “overdrive” refers to the fact that the gearing ratio serves as an extra feature in addition to the existing gears. Originally, the overdrive feature was manually activated. As transmissions have evolved, however, overdrive is included in most modern transmission systems.
How an Automatic Overdrive System Works
Now that you have a general understanding of what automatic overdrive systems are, let's discuss how they work. In essence, an overdrive unit operates with a faster transmission output shaft speed than the input rotation speed from the engine’s input shaft. In other words, the input shaft of an overdrive unit rotates more slowly than the output shaft. As a result, the torque from the engine gets multiplied so that the car overdrives beyond its peak power point for a more effortless driver experience.
In manual vehicles, the driver must move the clutch and stick shifter in order to put the vehicle into overdrive. Automatic transmissions, however, automatically shift into overdrive when driving conditions call for it. When overdrive is not in use, the overdrive system automatically allows direct drive to take place.
To get more technical, an overdrive system consists of a sun gear, planetary gear, and ring gears. When overdrive is in use, the sun gear remains stationary rather than turning the ring gear. Instead, the planetary gears, which have more teeth than the sun gear, rotate the ring gear. As a result, the ring gear turns further each rotation than the sun gear typically turns it when the vehicle isn’t in overdrive. Such an increase in rotation allows the engine to operate at a lower RPM while cruising at a given road speed.
Benefits of Automatic Overdrive Systems
- Improved Fuel Efficiency: One of the key benefits of automatic overdrive systems is the improved fuel efficiency that they provide. By allowing the vehicle to maintain a given speed while reducing the RPM of the engine, the efficiency of the vehicle effectively improves. As a result, you can travel farther and faster while consuming less gas and spending less money.
- Decreased Stress on Engine: As previously stated, overdrive units allow a vehicle’s engine to run at a lower RPM while maintaining a cruising speed. By reducing the engine’s revolutions per minute, less stress is placed on the critical vehicle component. Such a reduction in stress can result in improved vehicle performance, fewer maintenance issues, and a longer engine lifespan.
- Reduced Noise: Yet another benefit of allowing your engine to run at a lower RPM is noise reduction. By decreasing stress on the engine, your car will produce less noise, which results in a more comfortable and enjoyable driver experience.
- Enhanced Performance: When many people think about shifting into overdrive, they think about increasing the driving speed of a vehicle—and they aren’t wrong. While increasing speed isn’t necessarily the main focus of an overdrive system, an automatic overdrive system also allows your vehicle to cruise at a higher speed by bringing the RPM of the engine down at a given speed.
When Automatic Overdrive Should Be Used
As previously stated, an automatic transmission’s overdrive system will automatically shift itself into overdrive when driving conditions call for it. While the driver doesn’t need to manually shift into top gear, it can be beneficial to know when overdrive is useful for your vehicle and when it is not.
Essentially, an automatic overdrive is generally implemented during high-speed driving on highways or country roads. Typically, overdrive is used when the vehicle travels at an average speed of at least 40 miles per hour or above.
While overdrive proves useful in many driving conditions, there are certain scenarios in which overdrive is unnecessary or can potentially hinder the driving experience. For example, if you need to drive up a very steep hill or tow an incredibly heavy load, revving the engine at a higher RPM may be more beneficial. As such, overdrive capabilities should not be implemented during such occasions. If you notice your transmission switching back and forth between overdrive and the next highest gear while driving up a hill or carrying a heavy load, consider turning automatic overdrive off entirely for the time being to prevent constant gear switching. When driving down a very steep hill, your automatic transmission will also likely switch out of overdrive and into a lower gear.
Find High-Quality Overdrive Units at Transparts Warehouse
We hope that this complete overview of the automatic overdrive system has helped you gain a better understanding of the highly beneficial vehicle component. If you need to replace your vehicle's faulty overdrive unit or install a unit in an older vehicle that doesn’t currently have one, the Transparts Warehouse can help. We offer a wide range of high-quality transmission overdrive units from Gear Vendors.
When it comes to providing your engine with the power it requires to cruise at higher speeds, scale inclines, and optimize fuel efficiency, then proper gearing is crucial. For this reason, we pride ourselves on providing the overdrive units you need to keep your transmission running smoothly and efficiently. To learn more about our products and find the right one for your vehicle, contact us or browse our substantial online collection today.
