Arm stalling

Ok our issue is are arm keeps stalling it is a 5 bar design using 4 motors. It works for a few times then freezes. If we turn off the cortex it works a few times again then freezes. We think it must be a coding issue but are lost as to why it works a few times then not others. Here is our code can anyone help please.
if(vexRT[btn6U] ==1)
else if9vexRT[btn6D] ==1)

What’s a 5-bar?

Could you post a quick picture of the gearing on the robot.

Also I would guess that maybe you need to invert some of the motors.


if(vexRT[btn6U] ==1) { motor[rightarmT]=127; //motor[rightarmB]=127; //motor[leftarmT]=127; //motor[leftarmB]=127; } else if9vexRT[btn6D] ==1) { motor[rightarmT]=-127; //motor[rightarmB]=-127; //motor[leftarmT]=-127; //motor[leftarmB]=-127; } else { motor[rightarmT]=0; //motor[rightarmB]=0; //motor[leftarmT]=0; //motor[leftarmB]=0; }

Test each motor 1 by 1 to insure that they all individually try to lift the arm.

We are not using gears.

also code is actually else if(vexRT[btn6D]==1) typed it in thread wrong

I found your problem…

So your saying because we aren’t using gears thats why it works several times and then stops working?

Okay we really need to see a picture of your lift now.

Here is a photo of bot

Aaaaaaand there’s your problem. You need a gear ratio of AT LEAST 5:1. I recommend 7:1.

Ok but it works about 7 times then stalls and after a few minutes works again. How does having gears change that problem??

Seconded. You could throw some rubber bands on, too, if you don’t want to hang.

Also, how many motors are on your drive? It’s 4, right? And you chained the front wheel to move?

Adding gears will slow your arm down and multiply your torque so it doesn’t stall.

Okay so thats the problem. Gears allow more strength in an arm in exchange for speed. I would recommend a ratio were you power a 12 tooth gear and the arm is connected to either a 60 tooth or 84 tooth gear depending on if you want to hang. I am on my phone so linking is hard but there are nice explanations of “gear ratios” on line.
In all likelyhood it will lift faster because of the load on the motor.

wow I got ninjad bad
Lectures slow me down

We have only 2 motors driving the wheels, no problem. We have 2 motors on the intake 1 left and 1 right. We have 4 motors on the arm 2 right and 2 left. All motors are 393.

Put two more motors on your drive. There is no way your drive will survive a match. And put gears on your arm.

Thanks everyone for your help:)


Here is a picture of a lift geared 5:1 with 4 motors. It will lift countless times and even hang (but weighs less than 12 pounds) 5:1 will solve your stalling problems. If you do not have the heavy duty gears you can do 7:1 with the 84 tooth gears in a standard gear set.

are those geared for speed internally as well? :smiley:

but yeah, do as everyone above suggested and you’ll be fine

You should use bearings too. Right now you have a ton of friction.