Rack and pinion gears are used to convert rotation into linear motion. An ideal example of this is the steering system on many cars. The steering wheel rotates a equipment which engages the rack. As the apparatus turns, it slides the rack either to the right or left, depending on which way you switch the wheel.

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

Planetary Gearsets & Gear Ratios

Any planetary gearset has 3 main components:

The sun gear
The earth gears and the planet gears’ carrier
The ring gear
Each of these three components can be the insight, the output or can be held stationary. Choosing which piece plays which part determines the gear ratio for the gearset. Let’s check out an individual planetary gearset.

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

Gear Ratio
Sun (S)
Planet Carrier (C)
Ring (R)
1 + R/S
Planet Carrier (C)
Ring (R)
Sun (S)
1 / (1 + S/R)
Sun (S)
Ring (R)
Planet Carrier (C)

Also, locking any kind of two of the three parts together will secure the whole device at a 1:1 gear reduction. Notice that the first equipment ratio in the above list is a decrease — the output speed is slower than the input velocity. The second is an overdrive — the output speed is faster than the input quickness. The last is a reduction again, however the output path is normally reversed. There are several other ratios that can be gotten out of this planetary gear set, but they are the types that are highly Dry Screw Vacuum Pumps relevant to our automatic transmission.

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

On an involute profile gear tooth, the contact stage starts closer to one gear, and as the gear spins, the contact stage moves away from that gear and toward the other. In the event that you were to check out the contact stage, it could describe a straight collection that begins near one equipment and ends up close to the other. This implies that the radius of the contact point gets larger as one’s teeth engage.

The pitch diameter may be the effective contact size. Since the contact diameter is not constant, the pitch size is really the common contact distance. As the teeth first begin to engage, the very best gear tooth contacts the bottom gear tooth in the pitch diameter. But observe that the area of the top equipment tooth that contacts underneath gear tooth is very skinny at this point. As the gears change, the contact stage slides up onto the thicker part of the top gear tooth. This pushes the very best gear ahead, so that it compensates for the somewhat smaller contact diameter. As the teeth continue steadily to rotate, the contact point moves even further away, going beyond your pitch diameter — but the profile of underneath tooth compensates because of this movement. The contact point begins to slide onto the skinny portion of the bottom level tooth, subtracting a little bit of velocity from the very best gear to compensate for the increased diameter of contact. The outcome is that despite the fact that the contact point diameter changes continually, the acceleration remains the same. So an involute profile equipment tooth produces a constant ratio of rotational rate.