An Insider on Our Gearbox, Part One

Picture 1. ASCU FCS 

When the ASCU generation 2 was released, I found it rather interesting. I saw the possibility that a TM gearbox could be controlled by electric fire control system (FCS).

Yes, it was first electric FCS for a TM gearbox. The Electric FCS was already integrated in SYSTEMA AEG rifles made in Japan but  was quite expensive.

One day, I had an epiphany. It was the DC motor in an AEG TM gearbox system which resembles the gearbox for a servo motor in RC car. I thought I could use similar principles from a DC servo motor to make a true electric fire control system.

I started to design a new system. I believed that it would work properly the first time, but it was a big failure.

Picture 2. The 1st gearbox

As you can see in picture 2, I used as many legacy AEG parts I could. The gearbox worked perfectly as I had planned. However, the legacy parts were shot after conducting a stress test of about 10,000 rounds.

The 2nd gear and rack gear were not strong enough for the gearbox. The biggest problem was that the rack gear(Gear-rail) was not fit for heavy duty use, even though it was made out of nitride S45C(HRC 65). The hardness of the material was not a problem, but durability was. So, I decide to try to make new gears and a gear rail to be able to withstand the stress from the new gear box.

Picture 3. 2nd Gearbox prototypes. 

When I designed the 3 new gears  and the rack gear, I used two materials which were HRC 86-93 and nitride NAK80 (HRC 65-70).

Finally, the second prototype worked perfectly. I was happy because I was able to make a  gun I wanted, but it was only a tiny step forward. This gearbox was an achievement for my hobby life, but not a product for mass production.

First off, the mech-design was not suit for mass production. Even though the gearbox was made by Full-CNC-milling. Other parts? There are five internal moving parts which are very vital. As  shown in picture 4.

  1. Trigger bat : Hardened S45C steel (above HRC 65, Press cut)
  2. Trigger bar : Hardened S45C steel (above HRC 65, Press cut)
  3. Sear : A380 aluminum (Die-casting)
  4. Gear rail : Nitride NAK80 (HRC 70, Milled)
  5. Cylinder : Stainless steel 304 or S45C steel (Milled)

Picture 4. The Mech layer of EMD gearbox (Not actual mass product)

The design of gearbox is very simple. As you can see in picture 4, six elements makes 1 cycle. 1 cycle makes 1 shot in semi-auto. For full-auto, it repeats continuously when holding back the trigger.. And for various round-bursts, it is to repeat 2, 3, or desired amount, with holding back the trigger once. Holding back the trigger once means you don’t need to continuous pull the trigger for burst fire. Our computerized fire control system demonstrates these elements each cycle.

It has taken several years to finalize the mass product model. Why didn’t we  show the progress of our system? We didn't do want our product to be released early and then fail. However, we are now ready for mass production and proud to  show you our new products.

Thank you for reading.