Rack and pinion gears are accustomed to convert rotation into linear motion. A perfect example of this is actually the steering system on many vehicles. The tyre rotates a equipment which engages the rack. As the apparatus turns, it slides the rack either to the proper or left, based on which way you convert the wheel.

Rack and pinion gears are also found in some scales to turn the dial that presents your weight.

Planetary Gearsets & Gear Ratios

Any planetary gearset has 3 main components:

The sun gear
The planet gears and the earth gears’ carrier
The ring gear
Each one of these three elements can be the input, the output or could be held stationary. Choosing which piece takes on which role determines the apparatus ratio for the gearset. Let’s have a look at a single planetary gearset.

Among the planetary gearsets from our transmitting has a ring gear with 72 teeth and a sun gear with 30 tooth. We can get several different equipment ratios out of the gearset.

Input
Output
Stationary
Calculation
Gear Ratio
A
Sun (S)
Planet Carrier (C)
Ring (R)
1 + R/S
3.4:1
B
Planet Carrier (C)
Ring (R)
Sun (S)
1 / (1 + S/R)
0.71:1
C
Sun (S)
Ring (R)
Planet Carrier (C)
-R/S
-2.4:1

Also, locking any two of the three parts together will secure the whole device at a 1:1 gear reduction. Observe that the first gear ratio in the above list is a decrease — the output velocity is slower compared to the input quickness. The second reason is an overdrive — the output speed is faster than the input acceleration. The last is Oil less Air Compressors usually a reduction again, but the output path is definitely reversed. There are many other ratios which can be gotten out of this planetary gear set, but these are the types that are relevant to our automatic transmission.

So this one group of gears can produce most of these different gear ratios without having to engage or disengage any kind of other gears. With two of the gearsets in a row, we are able to get the four forward gears and one reverse gear our transmission needs. We’ll put the two sets of gears jointly within the next section.

On an involute profile equipment tooth, the contact stage starts closer to one equipment, and as the gear spins, the contact point moves away from that gear and toward the other. If you were to follow the contact stage, it would describe a straight collection that starts near one gear and ends up near the other. This means that the radius of the contact point gets bigger as the teeth engage.

The pitch diameter is the effective contact size. Because the contact diameter is not constant, the pitch size is really the common contact distance. As the teeth first begin to engage, the top gear tooth contacts underneath gear tooth in the pitch diameter. But notice that the part of the top gear tooth that contacts the bottom gear tooth is very skinny at this stage. As the gears turn, the contact stage slides up onto the thicker portion of the top equipment tooth. This pushes the very best gear ahead, so it compensates for the slightly smaller contact size. As the teeth continue steadily to rotate, the get in touch with point moves even further away, going outside the pitch diameter — however the profile of underneath tooth compensates for this movement. The get in touch with point starts to slide onto the skinny portion of the bottom level tooth, subtracting a little bit of velocity from the top gear to pay for the increased diameter of contact. The outcome is that even though the contact point diameter changes continually, the velocity remains the same. Therefore an involute profile gear tooth produces a constant ratio of rotational rate.