Anti-Reversal Latch Quick Question

[Spa]

Hi everyone,

I am simply requesting your knowledge on what you know on anti reversal latches. I myself have a fair bit of knowledge on the subject but I would like to further expand it with your help.

Some questions that do come to my mind is that, what would happen to an AEG's internals if a latch was not to exist? What would happen to internals if a AV latch has a very weak spring only making the latch go back to the bevel gear only slower then a normal spring? Would a pinion gear get damage?

This does not have to solely be focused on damage but also what it can do for an AEG. for example? would a quicker AV latch mean that there will be less damage to gears? The more latches on a bevel gear mean the faster an AEG can fire on semi auto?

Thank you for your support and input,

Spa

[m102404]

Neat question...I'm not sure if it's the most practical question, but interesting none the less. I'm sure that there are plenty of others out there that know a lot more than I do, but here are my thoughts on your questions/scenarios:

If the anti-reversal (AR) latch didn't exist, then the mechbox should still shoot. On semi, the the sector gear trips the cutoff lever and power to the motor is cut off. Typically, this is very close to where the piston is fully forward. If there was no AR latch, or if the bevel gear didn't have any catches, or if the bevel gear was in such a position that there wasn't a catch/notch "close" to the AR latch...the piston would spring forward to its fully extended position.

Same logic follows if the weapon was on full auto, but the amount/distance that the piston would return forward could be any amount from 90% cocked to already forward. The end result is that a second bb might be loaded and in position to fire, and thusly be propelled out the barrel by a less than normal amount of force.

Also, some tappet plates fins are triangular shaped (I think most are). But on the last CA Sportline mechbox that I worked on, the fin was very much a crescent shape (why? I'm not sure). If the gears were to unwind a significant amount, the nub on the sector gear could travel counter clockwise and negatively impact the fin, which could damage or bind the tappet/sector gear.

If the AR latch spring broke (I think this happened on one mechbox) I don't think that the latch would hit the pinion gear of the motor, but you'd have to check the individual clearance in your setup. The loose piece of spring could definitely jam up in the gears and cause a cascade of damage.

I've seen quite a range between "soft" and "stiff" AR latch springs. Some feel like they will barely keep the latch pressed against the bevel gear and others are a pain to keep pulled back while inserting the bevel gear. So far, all have worked and I have not noticed any functional differences.

I believe that the most significant impact of not having an AR latch present is the potential damage/stress the mechbox gears would impart to the motor. My understanding is such that the motors used in AEGs are meant to run in one direction only and that forcing them in reverse (i.e. as if when the gears were to unwind a significant amount) is not doing anything to maintain or prolong it's performance.

Note: The following *** paragraphs are more guessing than anything else and comments from more informed posts should be considered. I don't have enough spare parts to run some tests...but that would help to get some direct observations.

***More latches/notches on a bevel gear will "catch" the unwiding of the gears when power is cut off to the motor. Will the shot to shot semiauto fire speed be faster on a weapon with more notches on the bevel gear? My thoughts are, "not really", since power is cut off to the motor very soon (and consistently) after the cycle is complete. But I've not measured the time between trigger pulls on mechboxes with say only 2 notches and those with more.

***I do believe that more notches are beneficial in high ROF weapons when they are shot in Full auto, since the gears are arrested as quickly as possible after the power is cut off to the motor and there is less chance of a "double shot".

***I suppose that with very high ROF setups (i.e. extreme gear ratios, powerful motors and low powered springs) doubling on semi is possible...but it's beyond my experience.

[Spa]

Thank you for the valuable information m102404.

But to elaborate on motors, can they not move either way? for the fact that you can reverse the polarity and the motor can change directions? but would this be actually bad on the motor?

[dodger_me]

It dont know if its bad, but it defiantly reduces power

[Naglfar]

The sector will probably fuck up the tappet plate if it went backwards too far.

[m102404]

Originally Posted by Spa

......
But to elaborate on motors, can they not move either way? for the fact that you can reverse the polarity and the motor can change directions? but would this be actually bad on the motor?......

I'm not a tech head when it comes to electrical motors, but others on here are. I do know that if you attach the leads of the mechbox on reversed, you'll instantly blow your fuse (or heat up your motor if you're not running a fuse). Heating up your motor that way can't be good. ***I can only recall getting the wires reversed in while the AR latch was in place...so I can't say 100% that an AEG motor won't run in reverse. I'll try later if I remember, I'll have 3 rifles on the bench tonight.

Some MOSFET units have Active Braking, where a very short reverse pulse is sent to the motor after the shooting cycle is complete. It's not long enough to reverse the direction of the motor, but it is strong enough to "freeze" any overspin. www.extreme-fire.com has a video of this (or at least they used to).

[swatt13]

i always thought that the av latch prevented the spring from decompressing and as we all said counterspinning the gears. which the knob on the sctor gear would jam or dmage the tappet plate, but most importantly if you fired, paused and whilst you pause the gears would beging to counter, you pulled the trigger again, you could have a scenerio where your whole mechbox is moveing one way and your pinion is spinning the other. you would instantly strip the pinion gear or even damage the shaft of the motor.

[Spa]

Yeah swatt13 I believe you are correct on stripping the pinion gear if that would occur.

m102404, the fuse blows because the AR prevents the pinion gear from going in the other direction. so this will create a very very large load on the motor because it simply cannot move at all therefore increasing heat and blowing the fuse.

None the less, all good info from everyone!

[Flatlander]

I worked on a buddy's gun who had a modify AR latch installed (the one for the gearset) and it doesn't work on regular gears - ie. would not catch the latches on the bevel gear. After maybe a couple hundred rounds through the gun, his brand new modify piston (garbage IMO anyways) had the first tooth (from the back) folded/broken to the front of the piston and significant wear on most of the other teath on the 'wrong' side - caused by the piston moving forward while the sector was still engaged. So the AR latch is very important little piece.

On the motors topic, yes they will spin the other direction if the leads are reversed (outside of the grip/mechbox). I found on the motor I did it to that it was VERY slow compared to the proper direction. I don't believe this is bad for the motor, just inefficient. If you look at systemas new new Revolution mechboxes they have 4 gears in the mechbox - the extra gear causes the sector gear to reverse direction on a 'normal motor'. This is why Systema made a custom motor which is built to run in the opposite direction, so motor choices for the Revolution will be slim it seems.

[m102404]

Originally Posted by Flatlander

...
On the motors topic, yes they will spin the other direction if the leads are reversed (outside of the grip/mechbox). I found on the motor I did it to that it was VERY slow compared to the proper direction. I don't believe this is bad for the motor, just inefficient. ...

Thanks for posting your direct observations...now I don't have to risk my own gear just to find out what's what!

I've blown through plenty of gears and pistons just trying stuff out. Costly, but neat.

The original question may not be very practical...but I'm glad to see that there are those who will put some thought into it and share with others.

[Flatlander]

Haha, I got kinda carried away reading the other posts I forgot to answer your specific questions...

Originally Posted by Spa

Hi everyone,
Some questions that do come to my mind is that, what would happen to an AEG's internals if a latch was not to exist? What would happen to internals if a AV latch has a very weak spring only making the latch go back to the bevel gear only slower then a normal spring? Would a pinion gear get damage?

No latch - if the piston is partially in its cycle when the motor shut off the spring will push the piston forward, causing the gear train to run in reverse. Bad for piston as I've found out in one case. Gears should be okay (as they're meant to run in both directions). However, should you pull the trigger WHILE the system is running in reverse, I would expect bad things to happen to your pinion and/or bevel gears.

Weak spring vs strong spring - shouldn't make no difference unless the spring is even to weak to push the latch up against the bevel gear. In either case, the latch is always in contact with the bevel gear while the system spins so the latch doesn't 'return faster' because it's always there! It's how many notches on the bevel and how far the notch is away that will determine when the latch engages.

Originally Posted by Spa

This does not have to solely be focused on damage but also what it can do for an AEG. for example? would a quicker AV latch mean that there will be less damage to gears? The more latches on a bevel gear mean the faster an AEG can fire on semi auto?

See above for the first part...

I don't think you'll find more latches will give faster semi auto response as the piston always returns to the forward most position in semi. The only case I could see this actually working is with overspin - the gears spin after the cutoff level is engaged and actually pull back the piston a tiny bit back and the latch engages before it can return. I think the difference wouldn't be very noticable and that little bit of overspin isn't good for the piston should the latch not engage in time to stop it from reversing direction.