The Anatomy of A Gearbox

Category: Tips

Like all mechanical products, an airsoft gearbox can seem a little overwhelming at first. With a range of moving parts, one item not seated correctly can spell disaster, soon leaving you in a position where you’re taking your beloved airsoft gun to your local shop in parts because you’re not quite sure what you’ve done.

That said, in reality, the airsoft gearbox is not that complicated; and with a little bit of knowledge, you’ll soon find yourself accustomed to the intricacies of a range of different parts, allowing you to not only maintain your airsoft gun but also repair and upgrade it when needed. With this in mind, this month, we’ll be taking a look at the different parts of the airsoft gearbox, what they are, and what they do. Then over the next few months, we’ll walk you through the various upgrades you can make and how exactly you do them!

Please, though, if you are uncomfortable with working with your airsoft gun, take it to your local gunsmith instead of attempting to do things yourself. Just BB Guns take no responsibility for any failures when working with your gearbox. Instead, we intend to equip you with the information needed but proceed at your own risk.

So what exactly is in an airsoft gun? We take a look.


The gears within an airsoft gun are the driving component. These transfer power from the motor to the piston, allowing your airsoft gun to fire. There are four gears within an airsoft gun – the pinion gear, bevel gear, spur gear and sector gear. Each gear has its own ratio, all of which are torque multipliers, leading to an increase or decrease in trigger response time and rate of fire.


The motor is the power plant of any electric powered airsoft gun and is broken into – the armature, the can (with attached magnets), the ‘End Bell’, and the brushes. While it’s not a necessity to spend a fortune on a motor, we would suggest changing out your stock motor should it come with ferrite magnets. Neodymium magnets are far superior, and almost all aftermarket motors come with these equipped.


The piston is one of the hardest working parts within an airsoft gun and, as such, is susceptible to abuse, especially when airsoft guns are upgraded. Think of your piston in a similar light to the tyres on a car. Much like a car’s tyres, the piston is worn with use and will require upgrading and replacing based on how much it is used. Therefore, if you are shooting regularly, plan to keep a close eye on the piston, much like you need to keep your car’s tires replaced, rotated, or replaced.


Essentially part of the piston assembly, the O-ring is an equally important piece of your gearbox, and as such, we thought it important to mention it in a separate section. Attached to the piston head, an O-ring rests within a slot between the head and the piston itself. When the piston assembly moves forward, the O-ring assists in sealing existing air in the cylinder to allow the piston head to push said air along the cylinder head.


The spring essentially drives the piston assembly forward into the pack of the cylinder, which then compresses the existing air in the cylinder. Aftermarket springs all come with a rating that correlates to the spring’s stiffness. This stiffness will correspond with the FPS of your airsoft gun, with stiffer springs compressing the air quicker, leading to a higher FPS.


As previously highlighted, the cylinder is where existing air gets used to propel the BB, with the piston head driving the air through the cylinder. Depending on what barrel and what weight BB you are using, only a certain amount of volume is needed out of the cylinder to propel the BB all the way to the end of the barrel.


Bushings and bearings are somewhat uninspiring, but they are important and should be paid attention to. Bushings are solid pieces that tend to be more reliable. Bearings reduce friction to allow gears to spin with ease. While the size of bushings will not affect reliability, bearing size does, with the larger bearings being less prone to breaking or blowing out.


A standard trigger switch (by which we mean it does not have a MOSFET attached) is the on/off switch for the motor. It consists of a sliding contact that, when the trigger is pulled, makes contact to initiate the motor. This then allows your airsoft gun to fire, so as you can imagine, it’s somewhat important!

You can see our full range of BB Guns and Airsoft Guns on the Just BB Guns Ireland category product pages. We also have a large number of BBs and airsoft accessories, all at great low prices.

Just BB Guns Ireland: 13 Fashion City, Ballymount, Dublin, D24 FD82
Call us now: +44 (0)330 900 5224
E-mail address: [email protected]

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