We have already talked about it several times, we have made reference, we have seen in theory and in practice how it works, we have given advice on both maintenance and conservation, but we do not tire of saying that this mechanism is the soul of your AEG.
About the gearbox
It is its construction, its mechanics, its operation and its durability that determines the performance and life of your replica. IN this review, we will see everything Marui has done, from its beginnings to the present day.
Contrary to popular belief, the different versions of gearboxes that have been developed have not been made as enhancements to existing prior designs, but rather to the fact that they have to fit into the finite dimensions of a new weapon. Naturally some improvements are made in each new version, but the primary goal of each version is not generally to improve performance on new replicas. Gearbox version “1” was introduced along with Marui's first electric rifle, the FA MAS, in 1991 and is still in production…
There are always, and will be, modifications available on all gearboxes. The wiring and triggers are tremendously different from one replica to another, even though they may carry the same type of gearbox: For example, the two-stage trigger on the Steyer AUG requires special wiring, as well as the burst system controlled from the SIG 55x family (a simple oscillator with power transistors that are usually used by radio controlled cars), or to mention, the wiring that the replicas carry with the batteries mounted in the handguard, compared to those that carry it in the cylinder heads.
Mounted on: FA-MAS
It was the first gearbox conceived by Marui. The design was very simple and integrated the motor and wiring in the same mechanism box. It uses a special type of medium-sized engine, which is neither manufactured anymore, nor available in stores right now. The engine is the EG560 which have a good rate of revolutions per minute, but it is the lowest in the entire Marui range. The gearbox is very simple and looks very simple in construction with a bulky look. It incorporates a special type of anti-reversal latch, one end of which protrudes from the gearbox (and some pinches that I took with it using my old FAMAS), allowing the piston to go back. A similar design can be seen in version 4.
Due to its engine with so little force and the so rudimentary design (and mainly the lack of spare parts), the gearboxes of version 1 are not convenient to mount springs of more than M100.
Mounted on: MP5, G3, M16, M4A1, CAR-15
It is the most common model. It is available in two versions, one with small windows, the other without. The one with windows is very common in M16 families. Normally this gearbox uses long type motors. The standard gearbox does not support upgrades very well and has a flaw in its design that makes it very fragile. You can move an M100 spring without issue, and I've come to see gearboxes with M120 springs that didn't have any kind of internal reinforcement.
The weakest point of this gearbox is how sensitive the safety lever can be, which simply consists of a plastic strip that prevents the trigger from being pressed. Of course, the electrical circuit will stay open when powered, but the pin that is supposed to stop the trigger is very sensitive to breakage.
The gearbox presents a significant advance over version 1, and is much simpler in construction and easier to maintain and operate. Numerous reinforced models are available from different manufacturers. The version with windows can be mounted in the MP5 and G3 families, and does not represent any advantage over the model that does not have them.
Mounted on: MP5K and MP5A4 PDW, AK47, G36C, SIG 55x
Less than the G36 C, I have been a user of the other replicas, and it is my favorite. It is to say it somehow "dog meat". It is an improvement on version 2 with a lower profile, and very common in replicas that use AK or pencil batteries. It uses medium and long motors, and it is also available in several models, but in particular the MP 5 K - PDW does not bring that common “cage” feature that simply and easily fixes the motor to the top of the gear. It is the first version that mounts the "stopper rail" that helps to increase the durability of the whole set. Typically version 3 you can see the faces with springs like the M120 without needing to be reinforced anywhere.
They are available in reinforced versions of some manufacturers (JET, DTP or Systema). Due to its quality and durability, version 3 is the most popular custom to mount on other replicas, as it can become the example of Top's Minimi M249, which can be easily modified to accept this gearbox.
Mounted only on: PSG-1
It is the one of the only gear cases specifically designed for a replica, in this case the PSG-1 sniper rifle. It is a rare and unique design. Version 4 is only designed to shoot in semi-automatic mode with a “negative” gear timing cycle. Let me explain: in the other replicas, the spring is compressed once the trigger has been pressed to produce the shot, while here, the spring is already compressed, and when you pull the trigger, we release it, the shot occurs, and compress the pier again, waiting for the next one. Since this replica can afford the luxury of a longer barrel, everything in it is made in a big way: 590mm barrel, bigger cylinder, bigger spring, bigger gears, and therefore, bigger piston. It uses a long type motor, and like version 3, mounts the stopper rail to increase durability. Another unique feature of this gearbox is the lever to release the spring, to be able to store the replica for long periods of time, and that the spring is not damaged, that in fact this lever is part of the anti-reversal latch system (anti reversal ).
Another interesting detail the first time I demonstrated my PSG is that the gearbox is divided into two parts, where the gear assembly goes on one side, and the piston-spring-cylinder assembly goes on the other. This in my town is called a module, so it can be said that the true inventor of the modular gearbox has been Marui, however much Systema says that the design and invention was his, since he is the one he uses in his Training replicas Weapon System, and now ICS, with an identical copy of the Systema model. The aforementioned, makes the gearbox of type 4, the easiest to work and disassemble. Supposedly it can work with upgrades of up to 400%.
Mounted only on: UZI
It is the strangest design of all Marui. It is the only one made of plastic. Version 5 is the most compact of all existing gearboxes from the Japanese manufacturer. It has a very particular arrangement compared to classic gearboxes, since the spring is mounted in the front, making the piston move backwards instead of going forward as in other gears. This type of operation is called negative pressure operation. The internal barrel passes through the spring and the piston itself, and the air is redirected by baffles located in tunnels drilled directly into the nozzle. The gears are located at the rear and push a lever that in the turns of the gear set, pushes the piston. To carry out this thrust, the gears must go in the opposite direction to that carried by the other gears in the rest of the gearboxes, which means that the motor works in turns in a counter-clockwise direction (in other gearboxes, the motor rotates clockwise, that is, from right to left). Due to the plastic material used in its construction, the push lever, and the piston, it is not possible to upgrade it at all, since there are not even reinforcement parts made for it.
Mounted on: P90 and Thompson M1A1
It is the latest design and contains many improvements over other previous designs. It has a longer brake rail than even the version 3. It has an interesting solution to fix the washers in place, where those of the spur gear are oval in shape, thus preventing the washer from turning in the valve leaflet. gearbox, with which the grip of this is greater. Likewise, the grip of the cylinder head has been increased, which distributes the force much better than the previous designs and incorporates the same fixing for the engine as the version 3, completely surrounding the engine and keeping it in one piece in place. The reason for the design of this gear as well, is that it allows the motor to mount it at different angles depending on where it needs to be mounted.
The gear has a very compact design compared to versions 2 and 3, and can mount without problems and without reinforcing it at all springs up to an M120. There are reinforced versions from different manufacturers.