VexPro Drivetrain popping while driving

[Thad House]

We finally got to do alot of testing on our competition bot today, and we started hearing a popping from the drivetrain everytime it moves. We have a WCP SS gearbox, using belts to drive the outer wheels in a WCD style. We noticed it gets louder when we start putting the correct tension on the belts. It's not trying to run up the flanges on the pulleys, which was one of our thoughts. We are thinking the bearings might be popping under the constant load from the belt tension, but we pretty much have no idea what is causing it.

[SoftwareBug2.0]

Does it do this regardless of whether there is a load on the drivetrain? Does the noise go away if the robot is up on blocks?

[Akash Rastogi]

Post up pictures of your gearboxes.

[DampRobot]

Try running it on blocks, taking off the belts to see if the clicking stops, or rotating the wheels by hand to see if there's resistance anywhere.

[Thad House]

It does this on the ground or up on blocks. By hand it pops too but it doesnt feel like resistance, other then whats inherently in the gear reduction.

And I dont have any pictures of the gearboxes right now, but when we dont have the belts attached they don't do it. And they are standard WCP SS WCD versions. What in the transmission could cause a pop, unless something is snapping?

[DampRobot]

Originally Posted by sst.thad

It does this on the ground or up on blocks.

And I dont have any pictures of the gearboxes right now, but when we dont have the belts attached they don't do it. And they are standard WCP SS WCD versions. What in the transmission could cause a pop, unless something is snapping?

Sounds like it's in the belts then. Is the gearbox in the middle? Is there any significant resistance when you turn the gearboxes by hand?

[Thad House]

Originally Posted by DampRobot

Sounds like it's in the belts then. Is the gearbox in the middle? Is there any significant resistance when you turn the gearboxes by hand?

I edited my post after i saw yours. It does not happen when the belts are not attached, and its in the middle. But we still have no clue what would actually be popping on the belts, because we are looking and they are not riding up the pulleys. Maybe when the tension is added to the center, it does something odd to that center axle. The pop reverberates through the entire side, so its hard to tell exactly where it is coming from. And there is no significant resistance other then the gear reduction. the popping doesnt feel like a skip if you hold the wheel. its barely noticeable.

[DampRobot]

We've noticed similar popping too, but never thought much of it. If it doesn't change the resistance in the drivetrain, I wouldn't worry about it too much. From what we be seen on our bot, I'd guess that it was coming from the bearings, but I really couldn't tell you for sure.

[AllenGregoryIV]

We noticed a similar problem on our drive train today. After some investigation we believe it's the bearings moving in their seat. We have a custom chassis and a few of the bearing holes were deburred after powder coating a little too vigorously. I don't have enough experience to know if it will cause problems later on since it's the first time I have had this problem. The bearings aren'ts spinning in the holes they are just able to move a little, we'll be making our spacers a bit tighter to keep the flange fully seated.

[magnets]

Originally Posted by AllenGregoryIV

We noticed a similar problem on our drive train today. After some investigation we believe it's the bearings moving in their seat. We have a custom chassis and a few of the bearing holes were deburred after powder coating a little too vigorously. I don't have enough experience to know if it will cause problems later on since it's the first time I have had this problem. The bearings aren'ts spinning in the holes they are just able to move a little, we'll be making our spacers a bit tighter to keep the flange fully seated.

Use green loctite. They make some for use with bearings that are up to 0.02 (I think?) too small.

[wireties]

After putting 5+ hours of run-time on the robot our drivetrain is popping in a similar manner. The noise never happens unless the robot is under a load. It does not even happen when driving straight - only when turning or reversing direction suddenly.

So replace the belts or check the bearings? Both I reckon...