Beginners' Guide: Gearbox Versions
The world of AEG gearboxes is a lot to take in for someone new to the sport, and in the modern day and age it is remarkably difficult to find this foundational Airsoft knowledge out there on the internet. Many new players assume that the "version" nomenclature indicates a progression in power and skirmish capability, and thus assume a version 7 gearbox is objectively better than a version 2. This article is penned with the intention of clearing things up, and providing a basic, non-comprehensive guide to the most common gearbox versions in Airsoft.
Put simply, the difference between most Airsoft gearboxes is simply the shape of the shell, which varies in order to fit a gearbox into the form of various real-world rifle platforms. Gearboxes for different platforms will have unique parts, such as the selector plate, trigger, cylinder head and nozzle, but many platforms share the same gearbox shell, gears, cylinder and piston. Below we outline the most common Airsoft AEG gearboxes, detail some of their features and what sets them apart from the others.
Version 1
The version 1 gearbox was the first electric gearbox designed by Toyko Marui, back in the early 1990s. The version 1 gearbox is driven by a proprietary motor, and contains 3 gears which drive a spring loaded piston which compresses air and is used to propel the BB. The version 1 gearbox is known for its high rate of fire, but it uses a proprietary TM EG500 motor and unique gears and as such cannot take many internal upgrades. More modern FAMAS AEGs, such as the Cybergun and the Cyma use a modified Version 1 gearbox, which uses V2/3 gears and a standard motor which is compatible with aftermarket alternatives.
Version 2
The Version 2 gearbox is one of the most common gearboxes around today, alongside the version 3. Version 2 gearboxes are found in Airsoft AEG M4/AR15s, SMG-5s and G3s. These gearboxes use 3 gears, known as the sector gear, the spur gear and the bevel gear, together with an anti-reversal latch and an uncaged motor. The basic version 2 Gearbox has had many enhancements added by various manufacturers over the years, and often features a quick change spring system and radiused cylinder window corners for added strength.
Extended Version 2
The extended version 2 gearbox can be found in Classic Army and A&K SR25 style AEGs. This gearbox is identical to the version 2 in every way except the length of the cylinder/piston, which is elongated in order to provide additional air for the longer inner barrels used in these DMR style rifles.
Version 3
The version 3 gearbox is another popular gearbox, and is commonly found in AR36 AEGs, AK47/74 AEGs, AUG's and S55x series rifles. Whilst the version 3 shell is used in all of these designs, the nozzle, tappet plate, selector plate and motor cage type vary. The version 3 gearbox uses a caged motor, which makes adjusting motor height easy and increases the overall rigidity of the design. Gears, pistons and other small parts are cross-compatible between most version 2 and version 3 gearboxes. This gearbox is generally regarded as the best gearbox for high FPS builds, though version 2 gearboxes with reinforcements are equally suited.
Version 4
An Extended Version 2 gearbox, found in the Toyko Marui PSG-1. This gearbox is unique and uses a longer piston than the standard version 2 in order to provide additional air to facilitate the PSG-1's extremely long inner barrel. The gearset for the version 4 gearbox is also specifically designed for it, as it allows the PSG-1 to "pre-cock" the piston for a faster trigger response on semi-automatic.
Version 5
The version 5 gearbox is found inside the Toyko Marui Uzi, which is long out of production. This gearbox is considerably smaller than the others, and has a polymer shell instead of metal. This gearbox is the forerunner of the AEP gearbox as Tokyo Marui's gearbox for compact AEG's.
Version 6
The version 6 gearbox was designed around the Tokyo Marui P90 SMG, and the M1A1 Thompson SMG. Two SMGs which could not be more dissimilar! Such is the flexibility of the version 6 design. The version 6 was intended for use in unconventionally shaped guns, and is an excellent choice for custom builds because of this. The V6 provides a caged motor and is compatible with standard version 2/3 gears and piston though it requires its own nozzle and cylinder head, which varies in design depending on which platform the gearbox is being used with.
Version 7
Version 7 gearboxes are found in M14 AEG rifles, though there are two different forms they take. The original Tokyo Marui M14 gearbox uses newly designed gears, as do the Cyma M14 rifles, including the EBR. The AGM M14 uses a standard version 2/3 gearset inside a version 7 shell, and whilst it does not run as well as the TM and Cyma M14 rifles it retains parts compatibility with the more common gearboxes. Version 7 gearboxes found inside M14 EBR AEG's use a different motor cage than the standard version 7, to allow for a change in motor angle to fit the EBR Chassis.
Version 8
The version 8 gearbox is used in the Toyko Marui Type 89 AEG, and features a mechanical 3 round burst feature allowing for 4 positions on the fire selector, instead of the usual 3. It is similar in appearance to the version 2 but has a larger lower section, and as with the version 2 gearbox, uses an uncaged motor.
NGRS Gearbox/ Version 9
The version 9, more commonly referred to as the Tokyo Marui NGRS gearbox, is a more advanced design with a recoil system, functional bolt lock and refined internal parts for a leap up in performance. This gearbox is used in the Tokyo Marui M4 NGRS series and the TM416 Delta. The NGRS gearbox uses an uncaged motor which is compatible with other gearbox types, but the remainder of the gearbox components are proprietary and are not interchangeable with other gearboxes.
AEP Gearbox
The AEP gearbox is a miniaturised metal gearbox, following similar principles to the other gearbox variants but with a teeny tiny piston and cylinder, and three tiny gears. The AEP gearbox was designed from the ground up and is not compatible with any other gearbox parts, due to its shrunken nature. The original AEP gearbox can be found in some form in all Automatic Electric Pistols, and the SMG variant, being larger, is found in AEPs such as the MAC-10 and SMG-7, which use a slightly larger gearbox. The original or "machine pistol" version usually comes out of the box firing around 200 FPS, and the SMG AEP gearbox usually clocks in at around 240 FPS. SMG version of this gearbox can be upgraded to around 300 FPS, though this can put undue strain on the motor, which is proprietary and is hard to source. Shown in the image is the machine pistol AEP gearbox.
Support Weapon Gearbox
Support weapon gearboxes take various forms, and are generally heavily reinforced gearboxes optimised for full-auto fire. Support weapon gearboxes are generally compatible with standard version 2/3 gears, pistons and cylinders, and take standard AEG motors. Support weapon gearboxes can be found inside M60, M240, PKM and most M249 AEG's. These gearboxes don't have facilities for firing semi automatic, and are tuned for higher rates of fire than a standard AEG gearbox. Some support weapon gearboxes offer rate of fire adjustment, and are capable of using higher strength springs than most other Airsoft gearbox types. The gearbox shown the the image is from an A&K M60 MK43, though other support weapon gearboxes are visually similar.
So there you have it! Our Beginners' guide to Airsoft AEG gearbox versions. This guide should give you a basic working knowledge of which gearboxes are used in which AEGs, and the differences between them. This is by no means a comprehensive guide, and even two AEGs using the same gearbox version will have differing parts throughout, so if you are shopping for a complete gearbox, make sure you get the correct gearbox configuration for your particular platform, and if you are in doubt, feel free to contact us!