Keyang Accident

[Chaos204]

OK so we had an accident today and i am trying to assess the damages. we have both keyang motors driving an arm with a lot of torque. we are using gas springs to levy the load on the motors, but as we were installing today the arm fell. the arm nearly crushed the electronics, but a chair broke the arm's fall. (Nobody got hurt, they just wet their pants)

As it fell i heard clicking. Not knowing too much about the keyang it scares me. It seems to work OK. I cannot turn the gear with my hand with no power and with power it spins. when the motor is moving a load i hear the same clicking when it stalls.

Any Idea whether it is broken?

[EricH]

Originally Posted by Chaos204

OK so we had an accident today and i am trying to assess the damages. we have both keyang motors driving an arm with a lot of torque. we are using gas springs to levy the load on the motors, but as we were installing today the arm fell. the arm nearly crushed the electronics, but a chair broke the arm's fall. (Nobody got hurt, they just wet their pants)

As it fell i heard clicking. Not knowing too much about the keyang it scares me. It seems to work OK. I cannot turn the gear with my hand with no power and with power it spins. when the motor is moving a load i hear the same clicking when it stalls.

Any Idea whether it is broken?

Is the clicking coming from the motor or the breaker panels?

[kevin.li.rit]

Were the Keyangs being back driven as the arm fell?

[Chaos204]

Wow, had not thought of it coming form the breaker could it possibly be reseting in such a fast interval. If i was describing it i would say it was the motor, it sounded like a clutch or something. Does it have something protecting it form breaking itself like a clutch? It reminded me of a toy i used to have called Rrokenbok when you pushed past the motor with your hand it makes a clicking noise similar to this sound.

Originally Posted by Coffeeism

Were the Keyangs being back driven as the arm fell?

hard to tell it all happened so fast. I think we started to lower it slowly but th guy steadying the arm got surprised and drooped it. I assume when it fell the operator stopped pulling the joy stick.

[Cptn Patches537]

What is connecting the motor to the arm? You may be so preoccupied and worried that your belt might be skipping without you noticing it... I know this is unlikely but we used a belt last year with dual keyangs and it worked very nicely. we just had to design some improv tensioners to keep the belt from skipping.

[Richard McClellan]

I believe the worm gear inside the keyang motor is metal and the spur gear is nylon. We stripped two or three of the teeth on the nylon spur gear last year during some demos after our robot had been through one regional and championship. We ended up having to get a replacement from another team (special thanks to 499!) so that we would still have a working arm for future demos.

If you guys have the same problem we did, and that's what it sounds like, your arm would still work because one motor can support your arm when the spur gear in the other motor has its stripped teeth next to the worm gear. But, you might want to try and replace it just so that you always have both motors supporting the load. Hopefully a team in your area has a spare they're not using!

[Chaos204]

Any thoughts on how i might test to see if it is broken?

[MrForbes]

Two clues: 1. You heard clicking when the arm fell (I assume the motor was trying to hold up the weight of the arm). 2. You hear the same clicking when you run the arm motor to "stall".

It sounds to me like you have partly damaged the spur gear teeth inside the motor, and it can take only part of the load it is designed for, then starts to slip, the clicking sound is the gears skipping teeth as the worm gear turns and the spur gear just stays still.

Sounds like you need a new motor, and probably a few spares as well, or figure out how to make sure the load on the motor is never high enough to damage it again (which is hard to do!)

[JesseK]

Unfortunately neither the Keyang nor the Van Door motor seem to have the torque we've come to expect. Even the RS-540 with the right gearbox has more torque and is less susceptible to breaking.

You definitely are stripping a gear when it's under load. Either a tooth is cracked or breaking, or the plastic gears are flexing/grinding and are about to break.

[Stillen]

sounds like you may have broken part of the worm gear, I just tore one of ours apart, because like you we had/are having problems with the keyang motors. Inside there are only these tiny nylon worm gears, they are very susceptable to binding or crushing.... We stalled one of ours, drew almost 22 amps, now it is junk........ :-(