| mcguyver |
January 2nd, 2009 13:19 |
For those who are unfamiliar with the PTW and trying to get a handle on the technology, Systema has been using polyurethane nozzle o-rings in all their cylinders manufactured after summer of 2007. It is certain that this will be extended to the Revolution.
Prior to the use of polyurethane, they used to use Viton, and you could expect to have to change the o-ring after 10,000 rounds or less. This was simple enough to do to a PTW cylinder (about a 5 minute job), but would be hell to have to tear down a gun and gearbox for it.
Almost all of my cylinders have been re-built with the polyurethane nozzle o-ring, and I have never had to replace one since. Prior to that, the cylinders I used had gone through at least 2 re-builds each, and I kept some o-rings in my field repair kit.
My most used cylinder is the M130, and I have at least 20,000 rounds (likely more) on it without having to touch that o-ring.
Now, onto the electronics.
The Gen 3 electronics set (made from 2005-2007) was fine, but the Achille's heel was the EL-003 board (switch devices). They were sensitve to low voltage (especially while running under load), and would have a tendancy to blow up. They were rated for 30A through the board (as evidenced by the fuse), and under certain instances, you could blow up the board without blowing the fuse. The 2008 electronics set looked to improve this. The slimmed down from 8 devices to 2, and went with a larger FET case size and capacity. By doing this, they reduced the traces on the board, and increased it's capacity. The also removed much of the FET control circuits from the EL-003 and moved them to the EL-001 (main board), but needed to add 1 extra control wire (4-conductor ribbon now instead of the old 3) to do it. The also heatsinked the FETs to give them more capacity and endurance under load, and have done so with the Revolution by attaching the FETs to the gearbox shell.
The 2008 electronics also have some other tricks up their sleeves. They now will lock out the gun if the battery voltage is too low, and they monitor rotation direction of the sector gear. If you install your motor with reverse polarity, your sector gear will spin no more that 2 cycles in reverse and the gun will lock out function until this is remedied. With a preassembled gearbox though, I doubt this will be of much benefit as the sector gear will be blocked from reverse travel by the piston rack. But the other feature of current draw will help that situation. If the EL-003 tries to pass excessive current (like in a locked motor or motor fault), it will shut down the gun. In a PTW, you can see the fault on an LED which will flash on the EL-001 (main) board, and you know the gun needs attention. In a Revolution buried inside the body of a Classic Army M4, you wouldn't see that LED, but function may be stopped regardless.
I would advise that considering the location of the EL-001 (main) board within the gearbox itself (not in an external compartment like in the PTW), that greasing the gerabox be a matter of absolute minimum. I have no idea yet how excessive grease deposits would affect the EL-001 (main) board, I'm sure Systema has looked at it, but there should be no need to re-grease the gear train, ever. The PTW gear train doesn't require it, so I see no need to do it with the Revolution either.
There is no official word I have seen stating that the Revolution electronic do 100% of the functions that a PTW does, but it would seem logical that they used the same controls and circuitry for both. When it is in used and compared directly to the PTW then we'll know for sure.
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