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AEG Internal Parts, A guide to the internals of an AEG and how they work

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First off, I did not right this. The credit goes to Airborne101 of ASF among others mentioned.

I am only posting it because it is an excellent source of information.

 

 

Original post:

http://www.airsoftforum.com/board/AEG-Internal-Parts-t179019.html

 

 

 

This is a guide to the Gearbox or Mechbox of an AEG. This guide will primarily focus on Version 2 &3 gearboxes, however many parts are the same in other types of gearboxes. This guide is primarily to explain each part in the gearbox and how it works. A few brands are mentioned when needed, however this guide will not state that one brand or part is better than the other. Everyone has their own preferences and experiences when it comes to upgrading and replacing parts in their gun.

 

Disclaimer: Opening up and working on a gearbox takes some experience, patience and time. I (Airborne101) along with any other members mentioned in this guide/thread are not responsible if you break or destroy your gearbox. This guide is merely to inform you of the function of the parts in your gun.

 

Now if you are reading this guide, you are probably interested in how all the little parts in your gun work and make it fire. You may be trying to understand this so that you can become knowledgeable enough to fix or upgrade your gun, rather than send it to a store.

 

I. Gearbox Overview

 

It is assumed that you know how to disassemble you gun and now have the gearbox lying in front of you. If you do not know how to do this, check out the Gun and Gearbox Disassembly Guide.

http://www.airsoftforum.com/board/Gun-Gearbox-Disassembly-f204.html

 

A few reminders about opening your gearbox:

-Remember, the main spring has a lot of potential energy stored in it, and if it is compressed or not handled properly when you open up your gearbox, that energy will be released in the form of parts flying everywhere, so be careful.

-Before you start, make sure you have a clear area to work. I generally work on my gun on a work bench with a white sheet laid over it. The white sheet allows for me to see almost all the parts, even the small ones.

-The following is a short list of tools for opening your gearbox. Not every gun will need every tool, and some gearboxes may need more/different tools. This is a general list so that you can be prepared:

 

-Phillips Head screwdriver (most guns use Phillips heads screws to hold the two halves of the gearbox together)

-Flat Head screwdriver (useful for pushing parts around and holding some parts down. Not NEEDED, but useful to have)

-Tweezers (used to grab small parts and springs)

-Allen wrenches/keys (some gearboxes are held together by these screws)

 

All of the guides listed and more can be found in ASF’s Gun and Gearbox Disassembly Guide in the Upgrades & Modifications section.

Version 2 Disassembly Guide Credit to M4aRmY

Version 1 Disassembly Guide Credit to D0096F

Version 6 Disassembly Guide (2nd post after Tompson takedown) Credit to hsimoorb

Version 7 Disassembly Guide Credit to OpSic66

Version 3 Disassembly Guide (Starting at 2:25) Credit to Hydralover

Guides can also be found at www.mechbox.com

Now that you have your gearbox opened up, let’s explain what you are looking at. In the top half of the gearbox resides the compression parts of your gun. This includes the Air Nozzle, Cylinder Head, Cylinder, Piston Head and Tappet Plate. These parts are responsible for compressing the air and forcing the bb out of the gun. The Piston, Spring, and Spring Guide are actually part of the mechanical system of the gun, however they are also located in the top half.

 

In the lower half of the gearbox reside the mechanical components which include the Piston, Spring, and Spring guide located in the upper part, along with the Gears (Bevel, Spur, Sector from bottom to top) Anti-Reversal Latch, Shims, Bushings, and Cutoff lever. The Motor is also part of the mechanical system; however it does not reside within the gearbox (in most cases). Regardless, this guide will provide some information on AEG motors. These parts are responsible for pulling the piston and main spring back, building the potential energy that will be released, forcing the air to compress.

 

Located just in front of the gears is the electrical system. This includes the Trigger Contacts/Assembly, Wires, and Selector Plate. Outside of the gearbox, but attached to the wires are the Fuse and Connectors for both the motor and the battery. A brief description will be given on these as well, even though they do not reside within the gearbox. These parts are responsible for completing the circuit and causing the motor to spin.

 

A more in depth guide of how the gearbox works will be provided later in this guide, along with links to some cool videos of a model gearbox operating.

 

II. The Parts

 

This section breaks down the sections of the gearbox (Compression, Mechanical, and Electrical). In each section the parts are listed and explained, along with some basic upgrading information. Again this is not to tell you which brands are the best, or how to upgrade your gun, but simply to inform you of the function of each part.

 

Gearbox/Mechbox

This is the outer shell the holds all the internals together. They are usually made out of some form of pot metal. Aftermarket gearboxes can be CNC’ed (these are generally aluminum) and also made out of higher quality metals. The inside of the gearbox has numerous holes and slots for everything to fit into.

Notice the three holes in a triangular shape are the holes for the bushings.

th_gearbox.jpg

 

 

 

V2 Note: Version 2 gearboxes are notorious for cracking. They crack near the upper front where they are the thinnest and receive the most amount of stress. If you plan to create a high speed or high FPS setup, it is best to use a reinforced gearbox, or an STS (Shock Transfer System) to prevent cracking and failure.

 

IIa. Compression

Air Nozzle

The air nozzle (also referred to as the nozzle) is responsible for pushing the bb into the hop up chamber, and channeling the air from the cylinder assembly into the hop up chamber, and forcing the bb out of the barrel. The nozzle is attached to the tappet plate which moves back and forth when the gun is cycled (more of this will be discussed below with the tappet plate and sector gear). When the nozzle is pulled back, a bb is force upwards from the mag. The nozzle then is pushed forward and pushes the bb into the hop up chamber. The nozzle seals around the cylinder head’s nozzle and transfers the compressed air to the hop up chamber behind the bb. To decrease air loss between the cylinder head and air nozzle, some aftermarket nozzles have a built in O-ring (Systema, Guarder). Air nozzles are gun model specific, so make sure to pay attention to which air nozzle you are buying. Nozzles have different lengths due to the different distances they must transfer the air through in each gun. I.e. M4s and M16s have the same nozzle, but that nozzle is not the same as an AK47 or a MP5.

th_airnozzle.jpg

 

Cylinder Head

The cylinder head is the end cap that attaches to one end of the cylinder. It is responsible for sealing the cylinder, allowing for the air to be compressed by the piston head. The compressed air is forced through a small hole on the inside of the cylinder head which sends it through the cylinder heads metal nozzle. This metal nozzle feeds into the air nozzle. The cylinder head also has two anti-rotation holes, one on each side of the head. These holes fit over/around a prong/nub inside the gearbox to prevent the cylinder assembly from rotating. This is important because the tappet plate is located directly below it and if the assembly rotated, would block the tappet plate from functioning properly. Most stock cylinder heads are made of plastic or some other polymer, and generally have a single O-ring around them to seal against the cylinder. Many aftermarket cylinders are made of metal, and include a rubber backing to soften the impact of the piston head, and reduce the stress. Some companies also have a rubber bumper on the front of the cylinder head to cushion it against the gearbox as well. Some companies have a double O-ring cylinder head to create a better seal with the cylinder and obtain better compression. Each gearbox has a specific cylinder head, and they are generally not interchangeable between other gearbox versions.

th_cylinderhead.jpg

 

Cylinder

The cylinder is a long cylindrical tube, usually made of brass, however can be of other materials. The purpose of the cylinder is to contain the air that will be compressed to fire the bb. The piston/piston head assembly fits inside of the cylinder, which is pushed forward to compress the air within. The air is forced through the cylinder head which seals the front of the cylinder. There are five types of cylinders: Type 0, 1, 2, 3, and 4. Each cylinder has a hole in it placed at different lengths from the front (the Type 0 is a closed cylinder meaning it has no hole) The reason for the different hole placements is to match the volume in the cylinder to the volume of the inner barrel. Because of the hole, all the air before it escapes, then once the piston head passes it, it seals and the rest of the air is compressed. When installing your cylinder, make sure you place the hole at the correct end; otherwise you may notice a drop in your expected velocity due to not enough air being compressed. Listed below is a guide to what barrel lengths require what type of cylinder:

 

Type 0 (No hole): 450-580mm

Type 1: Systema makes this one, it has a hole in the edge and is said to be for M4/M16/XM177/AK47. It is essentially a go between for the type 0 and type 2

Type 2 (4/5 hole): 364-460mm

Type 3 (3/4 hole): 227-430mm

Type 4 (1/2 hole): 110-170mm

(21st Centry Airsoft/ArniesAirsoft)

 

Cylinders are interchangeable between all the gearbox versions currently in use. The cylinder head/cylinder assembly is a common place to have a loss in compression, so make sure you test it. Generally new O-rings solve this problem. You can also wrap some Teflon around the outside of the cylinder head.

 

 

 

Piston Head

The piston head is the part that physically compresses the air within the cylinder. It resides inside the cylinder, and is connected to the piston. The piston head has several small holes in the front. When the piston head is pushed forward, air is force through these holes which force the O-ring in the piston head to expand and seal against the inside wall of the cylinder. When the O-ring seals, the air cannot escape and is forced towards the cylinder head. Piston heads are generally made out of either aluminum (referred to as a metal piston head) or a polymer/plastic, generally Polycarbonate (referred to as a Polycarb piston head). Each piston head has its own benefits, and disadvantages. Metal piston heads generally do not deform, and can increase your velocity by a little bit. The disadvantage to a metal piston head is that it increases the stress on the gearbox due to its heavier weight. This can be particularly problematic if combined with a V2 gearbox due to the V2 having a weak front end, and subsequently failing. The advantage of using a polycarb piston head is that they are much less stressful on the gearbox. The disadvantage is that because they are softer, they are more likely to deform. It should also be noted that metal piston heads are generally louder, whereas polycarb piston heads are more quite. Piston heads can also come with bearings, but this will be discussed in the piston section, and mentioned again in the spring guide section. The piston head, more specifically the O-ring on the piston head is another place for compression issues to occur. This usually is due to an undersized or damaged O-ring and should be replaced. A #14 O-ring from a hardware store is all that you need to replace the old/damaged one.

Piston head is on right.

h

 

Note: The Air Nozzle, Cylinder Head, Cylinder and Piston Head all come in a bore up form. Bore up parts allow for more air to be compressed by making the inner diameter of the cylinder slightly larger, this increasing the volume within the cylinder. Bore up parts should be used for barrel lengths in excess of 580mm; otherwise you may notice a drop in velocity and/or range. Bore up’s can be used with standard length barrels, however many people on the ASF have mentioned problems and inconsistencies with them when using a shorter barrel. It is advised that you are or work with an experienced airsoft technician.

 

Tappet Plate

The tappet plate can fall under both the compression and mechanical sections. As stated in the air nozzle section, the tappet plate holds the air nozzle. The rear part of the tappet plate sits over the sector gear. The sector gear has a small nub, that when the gear spins, brings the nub around and pulls the tappet plate back. This pulls the nozzle back and allows for a bb to move upwards and be loaded. As the gear completes its rotation, the tappet plate “slips” off the nub and a small spring forces the tappet plate forward, to its original position. This pushes the bb into the chamber. Tappet plates are dependent on the gearbox version. They are made of plastic, and can sometimes snap. If your nozzle is not moving back and forth when you fire the gun, a broken tappet plate may be the reason why. Other reasons can be that the small spring on the tappet plate is not attached to the gearbox or tappet plate properly, or that the nozzle became dislodged from the tappet plate.

 

IIb. Mechanical

Piston

The piston is a hollow tube with some teeth protruding out of the bottom, and guide rails on the sides. The piston head is attached to one end of the piston via a small screw. In the other end rest the spring, which resides partway in the piston, and protrudes out the back. The guide rails encompass the guide rails on the gearbox and keep the piston straight during operation. The teeth on the piston are known as a linear or flat-toothed gear (because they are linear, not in a circle) which are engaged by the sector gear. Contrary to most pistons, an airsoft piston has nothing to do with the actual act of compression within the gun. The first gear on the piston is thicker/bigger than the rest because of the large amount of stress that is put on it when the sector gear first engages the piston. The last tooth (generally the last 3-5 teeth, depending on the piston) is made of metal due to the amount of stress put on the teeth from the compressed spring. Pistons generally come in two materials: Aluminum and Polycarbonate. Each piston has its own benefits, and disadvantages. Metal pistons can increase your velocity by a little bit. The disadvantage to a metal piston is that it increases the stress on the gearbox due to its heavier weight. This can be particularly problematic if combined with a V2 gearbox due to the V2 having a weak front end, and subsequently failing. Aluminum pistons also come with all metal teeth which do not wear as quickly as polycarb teeth do; however the metal teeth can strip the gears teeth rather than the piston teeth (or both) causing you to have to replace the gears. The advantage of using a polycarb piston is that they are much less stressful on the gearbox, and also that if something were to strip, the piston would strip before the gears. (Gears are more expensive than a piston. Which would you want to replace?) However this advantage can also be a disadvantage as well. Some polycarb pistons do come with all metal teeth as well. Generally for most setups, 3-5 metal teeth, and the rest polycarbonate, will be sufficient.

Piston is on left.

 

 

As mentioned before, some piston heads come with bearings. The bearing resides inside the piston and is screwed against the piston head. This bearing allows for the spring to rotate within the gun to relieve stress. The bearing can also act as a small spacer and increase velocity by a small amount.

 

Spring

The spring is the part that forces the compression system to do work. The spring can have a linear pitch (consistent spacing between coils) or non linear (varied spacing and pitch between coils). The non linear are designed to be easier for the gun to pull back, thus making for slightly quicker/more efficient trigger response. The spring resides partway inside of the piston, with the other end wrapped around the spring guide as the back stop. AEG springs generally come rated by their M or in other terms meters/sec. I.e. m110=110 meters/sec. Some springs also come rated by SP and %.

m90~ 295 ft/sec

m100~ 328 ft/sec

m110~ 360 ft/sec

m120~ 393 ft/sec

m130~ 426 ft/sec

m140~ 459 ft/sec

m150~ 492 ft/sec

m160~ 524 ft/sec

Each spring rating and company will have different variations in their velocity. It is best to do some research or post a question asking other members what results they have gotten with their springs. These numbers are just a conversion from meter/sec to feet/sec, however they should be close to what an airsoft spring is putting out. It should be noted that some companies (Madbull, Guarder) springs shoot hotter than advertised by their M or SP rating. It should also be noted that springs are rated for use with .20g bbs I.e. a .30g bb will not be shooting 360fps with a m110.

th_spring.jpg

 

 

Spring Guide

The spring guide is attached to the rear of the gearbox via two little prongs that fit in each side of the mechbox. The spring guides purpose is to guide the spring (hinted at by its name) as the spring is compressed. Without the spring guide the spring might bend and get in the way of the piston as it is being pulled back. Many stock spring guides are made out of a durable plastic, however many crack and need to be replaced. A metal aftermarket spring guide would be a good replacement; however some companies guns come stock with metal spring guides preinstalled. The spring guide has a small hole in the back that allows for the screw from the stock (mostly on m series guns) to screw into the back. This hole is also good for sticking a screwdriver in when trying to open the gearbox and assist in keeping the spring guide from rocketing out and causing damage.

 

 

 

Spring guides can also come with bearings, which function in the same way that the bearings that come with the piston head do. (See Piston section) It should be noted that only one set of bearings is needed. A second pair serves no purpose in relieving stress, only acting as a spacer to increase fps slightly. Many people prefer to use a bearing spring guide rather than a bearing piston head to keep the weight down on the piston head.

th_springguide.jpg

Bushings

The bushings reside in the walls of the gearbox. They are small cylinders that the axles of the gears fit into. There are 6 total; 2 for each gear, 3 per each side of the gearbox. The bushings are a very important part of the operation of the gun as they make sure the gears spin smoothly and don’t wobble around. Bushings come in 3 common sizes: 6mm, 7mm, and 8mm; however 9mm bushings are coming on the market as well. Different guns have different bushing sizes so make sure you check out your mechbox size before you buy your bushings. Wouldn’t want to end up with 8mm bushings when you have a 6mm gearbox. There are two types of bushings: Solid bushings and Bearing bushings. The solid bushings are just two cylinders, one inside the other. These are very good for high FPS setups as they can handle stress very well. The bearing bushings are two cylinders, one inside the other; however between the cylinders are several small ball bearings. The ball bearings reduce friction making bearing bushings great for high speed setups, and can give you a small increase in rate of fire. The disadvantage of bearing bushings is that they cannot handle a lot of stress, making them a very bad choice for high FPS setups. Too much stress can cause the ball bearings to break or be crushed. It should be noted that the bigger the bearing, the more stress they can handle. There are also nylon bushing that are used in some stock guns ™ that should be replaced with metal bushings as the nylon bushings can warp and cause problems due to friction.

 

Shims

Shims are very small metal washers that fit around the axles of the gears. They space the gears from each other and the gearbox, making them a very important part of the gearbox. Too loose of a shim job, and your gears can wobble and create pressure points and improper contact on the teeth meaning stripped gears, and your gun may not be able to pull a powerful spring. Too tight of a shim job, and your motor will have to strain to spin the gears. A perfect shim job has very very little wobble/play between the gears, but at the same time can spin freely. Shimming is an art and takes a little bit of time to learn how to do it.

 

Gears

The gears transfer the rotational motion from the motor to the piston. Almost every gun comes with a flat ratio set of gears. Gears can be upgraded to high speed or high torque sets depending on the demands of your gun. High torque gears are needed if you are using a high powered spring. High speed gears are used with lower powered springs, but give you an increased rate of fire. If you use high torque gears you will lose ROF, as well as if you use high speed gears, you will lose torque. Gears can also come in a helical version. These gears need to be shimmed much more carefully do to their special design. Helical gears are great for high FPS setups because they relieve pressure on the teeth due to the design having multiple teeth in contact at any given time.

A little bit about gear ratios and Torque vs. Speed

http://www.airsoftforum.com/board/gears-AEG-t180747.html

 

1. Bevel Gear

The bevel gear is the first gear and is located in the bottom of the gearbox. It is in contact with the pinion gear from the motor, and the second gear, the spur gear. The middle teeth that have a wave shape are for engaging the anti-reversal latch. The outer teeth (teeth on the area with the largest diameter) are in contact with the pinion gear. The smaller gear is in contact with the spur gear. The large flat side of this gear faces the right side of the gearbox. This gear is place over the spur gear; therefore it must be placed in the gearbox after the spur gear. Due to it being in contact with the anti-reversal latch, it can be difficult to keep this gear in place when trying to close the gearbox.

th_bevelgear.jpg

2. Spur Gear

The spur gear is the second gear in the gear train and is located in the middle. It transfers power from the bevel gear to the sector gear. The spur gear also has two sets of teeth, with the outer teeth contacting the bevel gear. The inner teeth contact the sector gear. The large flat side of this gear is placed against the left half of the gearbox. This gear must be placed in the gearbox first because the other two gears reside on top of it.

http://i794.photobucket.com/albums/yy224/modeler1945/Airsoft%20Parts/th_Spurgear.jpg

 

3. Sector Gear

The sector gear is the last gear in the gear train. It is easily recognizable by its two sets of teeth; however one set of teeth only exists around half of the gear. This gear engages the piston via the larger half set of teeth. When the teeth run out, the piston is release and is pushed forward by the spring. The smaller teeth contact the spur gear. This gear is placed in the gearbox over the spur gear, with the small teeth facing the left side of the gearbox. On the same side as small teeth is a cam (small roundish nub) that engages the cutoff lever. On the opposite side is a small round nub that protrudes from the gear. This nub engages the tappet plate and pulls it back during its revolution. As the nub reaches the bottom of the gear during its revolution, it releases the tappet plate, allowing the tappet plate to slide forward.

Front

th_Sectorgearfront.jpg

Back

th_Sectorgearback.jpg

 

 

It should be noted that there is also a gear attached to the motor shaft. This gear is called the pinion gear. If the motor height is not properly adjusted, this gear can experience a lot of wear and need to be replaced. This gear is either pressure fitted to the motor shaft, or affixed via a small set screw. If it is pressure fitted, you will most likely need a special tool to remove and reattach the pinion gear.

 

Anti-Reversal Latch

For a lack of better words, the anti-reversal (also referred to as the ARL) latch is an annoying little _____! (Insert any negative word here. Cusses work great) This piece sits in a small hole in the gearbox. Attached to it is a small spring which provides the force that pushes it against the bevel gear. The purpose of the ARL it to prevent the gears from revolving backwards should the piston become semi compressed during operation. Although important, this piece can be difficult to keep in place when trying to close the gearbox. Many people place a small magnet under the gearbox at the hole to keep it in place while closing the gearbox.

th_antireversallatch.jpg

 

Motor

Without getting too much into the motor, it is what provides the force to power the gun. When you pull the trigger, a circuit from the battery to the motor is completed, and the motor spins. The shaft with the pinion gear attached rotates, and the rotational motion is transferred to the gears. AEG motors come in 3 basic forms: Stock, High Speed, and High Torque. Stock motors generally have a nice balance of torque and speed. They can generally pull up to a m120 spring and have a rounds/sec of 10-20 RPS (with the stock flat ratio gears). High speed motors spin faster and can increase your guns rate of fire, however these motors cannot pull as powerful springs. High torque motors can pull more powerful springs, but give of some of their speed. Torque motors also have quicker trigger response. (Trigger response is the delay from when you pull the trigger to when the bb actually starts traveling down the barrel) Different company motors have different performances.

th_motor.jpg

 

 

Cutoff Lever

The cutoff lever helps regulate the fire mode, and make the gun fire in semi when you want it to fire in semi, and full auto when you want it to shoot in full auto. The cutoff lever is affixed to the left side of the gearbox, just behind the trigger assembly. It is connected to the selector plate via a small spring that moves it into the correct position when you select your fire mode. When the gun is set in semi, the cam on the back of the sector gear pushes the cutoff lever forward at the end of its cycle, causing it to interrupt the circuit and forces the user to pull the trigger again in order to fire another shot. When the gun is set in full automatic, the cutoff lever is moved so that it does not interact with the cam on the sector gear, thus allowing for a continuous circuit and will fire for as long as you hold the trigger.

 

IIc. Electrical

Trigger contacts/assembly

The trigger contacts/assembly can be considered the “switch” in this circuit. When the trigger is pulled, it moves a small metal plate between two other metal plates, and completes the circuit. So long as the trigger is pulled, current is flowing through the contacts; however if the gun is in semi auto, the cutoff lever will be moved and cutoff the flow of current, thus interrupting the circuit.

 

Selector Plate

The selector plate is a small plastic piece located on the outside of the gearbox. It is engaged by the fire selector on the outside of the gun. By moving the fire selector, the selector plate is moved. When the selector plate is moved, it pushes on the contacts inside of the gearbox, and also moves the cutoff lever to engage the semi auto action.

 

Wires

The wires connect all the electrical components together. They connect the battery to the trigger assembly, the trigger assembly to the motor, and the motor back to the battery. When the circuit is completed, (via pulling the trigger) current flows from the battery to the motor, causing the motor to spin. Current is also sent through the trigger contacts because it is part of the circuit. For wire selection, check out Golgo 13’s AEG Electrical Guide.

http://www.airsoftforum.com/board/Aeg-Electrical-Guide-t104376.html

 

Fuse

The fuse is a small glass tube located somewhere on the wire between the battery and the motor. It is generally encases in a small plastic case to protect it and located in an area that is easy to access. Inside the glass tube is a small strip of metal that allows the current to flow through. The current protects the electric system from current spikes. If the motor is trying to draw too much current (due to a problem like a gearbox lockup/jam) or the battery outputs a spike in current, the fuse melts and breaks apart. When it breaks apart, the circuit is no longer complete and current stops flowing. A blown fuse is a very common reason for a gun not to fire, and it is a good idea to check it before opening the gearbox. Even if you are not comfortable opening up your gearbox, the fuse is very easy to replace and replacement fuses can be found at your local hardware store. Most guns come with a 20amp fuse (TM’s come with 15amp) but it is generally ok to replace the fuse with a 30amp or 35amp fuse.

 

Connectors

The connectors do exactly as it sounds like. They are attached to the wire ends that connect to the motor, and again to the battery. The motor connector is generally a Tamyia connector. These connectors wear out rather quickly, and may need to be replaced. They can be replaced with another set of Tamyia connectors; however a better choice would be Deans connectors. They last longer and have less electrical resistance. The motor connectors are generally L shaped and fit over/around a small thin piece of metal protruding from the back of the motor.

Tamyia

 

th_tamyiaconnector.jpg

III. How It All Works

This animation http://www.mechbox.com/data/how-the-mechbox-works.html

(Mechbox.com) of how the gearbox works is one of my favorite. Obviously everything happens much faster, however this slows it down so that you can see all the things that are going on.

 

When you pull the trigger, a circuit is completed and current flows from the battery to the motor. The motor spins, spinning the gears. The sector gear spins and grabs the piston and starts to pull it back. At the same time, the nub on the sector gear grabs the tappet plate and pulls it back, allowing for a bb to be pushed up into the hop up chamber. As the nub reaches the bottom of the gear, the tappet plate slides off, and is pulled forward by the small spring attached to it. The nozzle attached to the tappet plate pushes the bb into the hop up chamber. As the sector gear completes its rotation, the piston is released and pushed forward by the spring. As the piston assembly moves forward, air flows through the holes in the piston head and expand the O-ring so that is seals against the cylinder wall. The air is compressed and forced through the cylinder head and nozzle to the bb. As the bb starts moving forward, the hop up bucking/rubber grabs the top of the bb, imparting a backwards spin on it. The bb leaves the barrel and travels towards the target, hopefully resulting in a hit.

 

And with that concludes this guide. More pictures will be posted soon. If you have any information that you would like to add to this, please PM me, and I will see what I can do to work it into the guide.

 

Works Cited

21st Centry Airsoft/ArniesAirsoft. Cylinder Hole Location vs Barrel Length Guide Chart. 1 December 2004. 7 March 2010 <http://www.arniesairsoft.co.uk/?filnavn=/articles/21c/cylinderandbarrels.htm>.

 

Mechbox.com. How the mechbox works. 13 March 2010 <http://www.mechbox.com/data/how-the-mechbox-works.html>.

 

Credit goes to Golgo13 for his electical guide, and M4aRmY, D0096F, hsimoorb, OpSic66, and Hydralover for their respective gearbox disassembly guides.

 

Credit goes to SHWELL, and a huge thank you for the pictures.

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That was a good read and a good reminder of things. Here are a couple pics to help illustrate what internals look like and how they work.

 

ICS Gearbox (Old pic)

ICSAEG.jpg

 

AEG.gif

 

~Joker out....

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There are several pics that did not make it in the transfer that are supposed to be in there, I will add them in when I get around to it.

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Really good read.

 

Those mockups of internals and the animated GIF were very helpful as well.

 

Please check the dates of posts to avoid necroposting. - Endgame

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