My gearbox locked up when I switched to a CQB spring

[KraftaN]

I recently tried to switch spring on my new "AT-NY06 Sword Carbine LITE Mosfet". I usually run a M120 but I decided to try a SP90 spring for some CQB gameplay. I successfully changed the spring with no hiccups and dry fired a few times on semi. Everything worked as intended until it shoot twice (on semi) and then locked up my gearbox.
 



I switched to my more powerful spring and managed to get it to work again by switching the gun to full auto and dry firing a few times (this might not have been the best way to fix it), and it has worked ever since.



Since I'm pretty new to Airsoft I'd appreciate if anyone has an idea why this happened and or how to prevent it in the future.
Thanks in advance!

 

[Terry_Rist]

Are you running an 11.1v battery? If so it is most likely that you have run into premature engagement (look it up for a better explanation) but basically with a weak spring and a big battery/fast motor and gears, the piston doesn't reset fast enough so the gears catch on the piston rack part way down. If this isn't the case then it could realistically be pretty much anything that locked up the gearbox. 

 

[ak2m4]

What brand was the M120?  Was it stock? 
What FPS / Joules were you getting with the M120? 
Were you running it as a DMR? as a M120 should push you way over the legal limit

As @Terry_Rist said most likely the motor is spinning the gears too fast for the sp90 spring to cope.  Moving to a 7.4v battery should fix the issue but seems like you've perhaps got some fps issues. 

Anyone remember if Arcturus short-stroke their gears on these cheaper end models?

 

[KraftaN]

Are you running an 11.1v battery?

Yes, I am indeed running a 11.1 lipo battery. I was thinking that this might be the issue but since I don't have any other batteries I've been unable to test if this is the case.

What brand was the M120?  Was it stock? 
What FPS / Joules were you getting with the M120? 
Were you running it as a DMR? as a M120 should push you way over the legal limit

Yes the m120 was stock, and I'm getting around 375ish fps with .25 bbs which is around 1.6 - 1.7 joules (and where I live most fields have a 1.7 joule limit for automatic guns). Since I live in Sweden the laws are very loose. It's technically legal to run up to a 10 joule airsoft gun and 3 joule if it's automatic. 

Moving to a 7.4v battery should fix the issue but seems like you've perhaps got some fps issues.

What makes you think I've perhaps got fps issues?

 

[ak2m4]

Ahhh you're in Sweden, sorry assumed you were in the UK.  Forget what I said about the fps issues.

 

[Rogerborg]

What makes you think I've perhaps got fps issues?

Just that we assumed from your excellent English that you were in the UK with our 2.5J / 1.3J auto limits.

Anyone remember if Arcturus short-stroke their gears on these cheaper end models?

We have very different ideas on what constitutes "cheaper end"

No idea, they do claim to have short stroked 13:1 gear in other models, and a decent neodymium motor in the AT-NY06 so on 11.1V it could very well have prematurely engaged.

Alternatively it was just one of those freak incidents where the spring ended up fully compressed and the motor stalled out and couldn't pull it further - although with that motor and 11.1V that doesn't seem likely.

 

[KraftaN]

Thanks lads for all the help! I'll probably go and buy a 7.4V liPo battery to hopefully counteract the issue. Many thanks!