Gears

Gears are one of the main parts of the AEG gun. It is thanks to them that the airsoft gun can shoot. Their function is to transfer the engine speed to the piston comb, thus causing the point to be cocked and then fired.

The material from which the wheels are made is most often die-cast and CNC milled:

• Cast wheels are found in basic guns. Their advantage is definitely the cheap price, but they are not suitable for thicker springs. Also, there can be a problem with dimensions, the wheels can be crooked. Such wheels are then difficult to pad.
• 

CNC milled wheels are almost perfectly straight thanks to precision machining, the material is much stronger than basic wheels, so they are suitable for stronger springs.

What types of gears can be found in a gun ?

In total, there are 3 main gears in the AEG gun, namely piston, centre and motor gears.

• Motor wheel allows the motor to spin the other wheels. There is also an anti-reverse latch which protects the air and the wheels against possible reversing and therefore destroying the parts.
• Centre wheel has a different gear ratio
• Piston wheel is, as the name suggests, allows the piston to be cocked. In case there is a problem with the feeding of the balls, it is possible to put a so-called cam on this wheel.

What types of gears are most commonly used ?

• Fast gears (16:1, 13:1, 12:1) are wheels where the center wheel has fewer teeth, so it cycles faster and this results in faster shooting. At the same time these wheels are not suitable for use with strong springs, there is a risk of breaking the teeth. They are often used in conjunction with lightweight pistons.
• Standard (18:1) is found in basic weapons. It's a compromise between speed and load. With a good tuning of the mechabox we can not only have a very good cadence, but also there is the possibility of using stronger springs without the threat of damaging the teeth.
• High torque (100:300, 100:200) are wheels specially designed for very strong springs. They often have an helical type of toothing. These wheels are absolutely not suitable for building speed guns.

You can also find half-geared (1:32) or even a combination of speed and high torque ( 14:1).
With half-geared wheels, it is also necessary to use a piston with a half comb.

Delay tappet is a small, usually plastic, part that is able to solve the problem of insufficient unlocking of the hop up chamber. The cam actually extends the time that the chamber is unlocked, thus correcting the problem of bullets skipping when firing.

In addition to the standard gears, there are special gears such as SR25 gears or DSG gears ( dual sector gear) where the teeth on the piston gear are not in a row, but there are 8 teeth on one side and 8 teeth opposite.
This design results in a much higher cadence gun, as it fires twice per turn of the wheel, but the piston extends to about 50% of its length. So it is necessary to use stronger springs to give the gun usable power.
It is also recommended to use a special DSG piston with these wheels.

What does it mean to shim the wheels and how to do it correctly ?

Shimming means to define free space between the wheels using shims, as well as the clearance between the axle and the bearing. Proper shimming will ensure long wheel life, the gun will be quieter and the gun will be more reliable overall.

We'll break this process down into several steps:

1. We start with the center wheel. Put the wheel in the middle bearing and try to turn it. Most likely, it will grind. So we'll use the smallest size shim and test the wheel again. If we need to add another washer, we can use one washer one step larger instead of the two smallest. Then we use the smallest pad again and test again. Repeat these steps until the wheel stops scrubbing. We try to keep the gap between the body and the underside of the center wheel as small as possible. The ideal situation is one where the wheel is turning freely, but as soon as the smallest pad is removed, the wheel will start to scrub.
2. Now we need to pad the other side of the wheel as well. We need to add enough shims so that the wheel has no free space. The main thing we need to check is the smoothness of the movement, which we test by spinning the wheel, it should spin without any resistance. In this step it is very important to screw the two halves of the mechabox together, we recommend using 3 screws as close to the wheel as possible. This simulates a fully assembled and bolted together mechabox. Often when the two sides of the mechabox are joined, the wheels will turn, but as soon as they are bolted on, they will start to scrub. If we find resistance, we reduce the top washer. We will repeat this until we achieve smooth wheel rotation.
3. Once we have the center wheel perfectly padded, we'll continue around the piston wheel. After inserting the wheel, we will watch to make sure the wheels are not rubbing against each other with the walls. If they are, we need to pad the piston wheel. Again, we'll start with the smallest possible shim to avoid damaging the wheels later. We must remember that the teeth on the wheels must fit together absolutely precisely, with the wheels acting on each other with as much surface area as possible, only in this case will the wheels withstand a much greater load. Once we are sure of the bottom padding, the top must be padded again. We will repeat the same procedure as for the centre wheel. Next, we will determine the wheel clearance and the resistance to rotation.
4. We will do the same for the last wheel, the motor wheel.
5. Once we are sure that everything is ready, we will screw the two halves of the mechabox together and test the wheels' freedom of rotation, their noise and any resistance. If the wheels scrub or don't turn easily, a correction to the previous step should be made.
6. Once we are sure that the wheels are well padded, it is necessary to lubricate them with grease before final assembly of the mechabox. Ceramic grease is very suitable for this purpose. We put a small amount of lubricant on each tooth so that it is completely covered, but not too much, otherwise there is a possibility of the lubricant getting into, for example, the electronics and there is a possibility of destroying them.