The principle behind fixed gear transmissions is straightforward.
In a set of interlocking gears, one gear serves as the driving wheel and power is input into it. The other gear functions as the driven wheel, from which power is output.
There are gears that serve only as a transfer station. One side engages with the drive wheel and the other with the driven wheel, allowing power to pass through it. This type of gear is known as an idler.
In a gear system that includes planetary gears, the situation is different. There are planet carriers, which consist of three rotating shafts, and a clutch or brake can be used to limit the rotation of one of the shafts, leaving two shafts for transmission.
This allows the relationship between the intermeshing gears to be combined in many ways:
- Power is input from the sun gear, output from the outer ring gear, and the planet carrier is locked by the mechanism.
- Power is input from the sun gear, output from the planet carrier, and the outer ring gear is locked.
- Power is input from the planet carrier, output from the sun gear, and the outer ring gear is locked.
- Power is input from the planet carrier, output from the outer ring gear, and the sun gear is locked.
- Power is input from the outer ring gear, output from the planet carrier, and the sun gear is locked.
- Power is input from the outer ring gear, output from the sun gear, and the planet carrier is locked.
- The two powers are input from the sun gear and the outer ring gear respectively, and are synthesized and output from the planet carrier.
- The two powers are input from the planet carrier and the sun gear respectively, and are combined and output from the outer ring gear.
- The two powers are input from the planet carrier and the outer ring gear respectively, and are combined and output from the sun gear.
- Power is input from the sun gear and is output in two ways from the outer ring gear and the planet carrier.
- Power is input from the planet carrier and is output in two ways from the sun gear and the outer ring gear.
- The power outer ring gear is input in two ways from the sun gear and the planet carrier.
In a car, there is only one engine and four wheels. The engine’s speed and torque characteristics are quite different from the driving requirements on the road. To properly distribute the engine’s power to the drive wheels, the characteristics of planetary gears can be utilized, such as in automatic transmissions. Different gear ratios can be obtained by varying the relative motion relationship of the components through the clutch and brake.
