Automatic Transmissions 101
Automatic Transmissions 101
Most drivers operate cars that use automatic transmissions rather than manual. Both do the same basic job, but each approaches the task differently. The main differences between an automatic and manual are that the former doesn’t require the driver to use a clutch to manually shift gears. Everything happens automatically. In this article, I’ll provide an overview of an automatic transmission, including the parts involved and how they work together.
The Parts
Automatics use a planetary gearset to change and manage the different gear ratios as your car accelerates and decelerates. They also include internal bands and clutches which help lock various components of the gearset. These bands and clutches are managed by a hydraulic system. Finally, a pump is used to shuttle fluid through the parts. The gearset is the most important component of the system and is responsible for controlling the various gear ratios. It’s comprised of sun, ring, and planet gears, each with different numbers of interlocking teeth.
How They Work Together
Manual transmissions require the driver to slide gears along multiple shafts with the stick shift knob. As these gears slide, different gear ratios are achieved in order to allow the engine to maximize power. Automatics don’t use sliding gears within the planetary gearset. They’re always attached to the other gears along their teeth.
Try to imagine a top view of the connected system. The sun gear is in the middle with the planets attached on the exterior. Those components are contained within the ring gear, to which the planet gears are attached. The ring gear is connected to the engine through the input shaft and everything is contained with a planet carrier. The carrier holds the sun gear in place. As the ring turns, the planets turn, walking around the stationary sun gear.
Watch For Warning Signs
A lot of things can potentially go wrong with automatic transmissions. The key is watch for signs of impending problems. For example, get into the habit of checking the fluid regularly. Ideally, it should have a transparent, reddish hue. If it looks dirty or muddy, or smells like something is burning, have a technician take a look. You may need to have the fluid drained.
Also, watch for persistent leaks. Too often, drivers become accustomed to their cars developing minor oil leaks and neglect to check whether fluids are leaking from the transmission. At some point, enough fluid will leak that it can sustain heavy damage.
Automatic transmissions are complex and this article is only meant to provide a basic overview. It’s important to learn how they work and the potential issues that can emerge over time. In a future column, we’ll explore the various components and how they operate in more detail.
