M3 Help Needed!!

[Armortek]

I don't think that sound comes from the module boxes - it sounds like an electromagnetic whine from the motors.

It is hard to draw conclusions from the short video, but it looks like the sound happens before the right track moves either forwards or backwards - if that really is the case then that would point to something binding the motor before it breaks the bind and can rotate freely.

[Matthew Whiteley]

That sounds logical but It ran very smoothly on the bench test and with the tracks on off the ground.

I suppose I will have to take off the drive sprockets and the final drives to have a look in there as I have already taken the motors out a few times.

There must be a solution somewhere.

[Mark Heaps]

An electromagnetic whine is created by electric motors which are not turning. This could be caused by the motor or drivechain phsycally binding OR lack of current to overcome the initial inertia. Once it is is moving, does it slew to one side ? Can you hear any mechanical binding noise, grating, rubbing ?

[Matthew Whiteley]

Hi Mark,

Thanks again for helping. No, I don't hear any binding or grinding. Just the electronic noise. Once it gets going it moves ok. The batteries are brand new and the voltage looks good on the Box.

I have it set up on a two stick drive at the moment so any play to left or right is more than likely attributed to my inputs. The binding does present more on the left (port) side than the right.

It ran super clean and quiet when I tested it without ground contact.

I think my next step will be to take the drive sprocket off and the final drive to see if anything is binding.

I really appreciate the thought that you have given this, it feels great having community support. Armortek tanks are quite the investment and it will feel good once its working properly.

Matt

[Mark Heaps]

Hi Matthew,
As you have it set up for 2-stick steering at the moment, that could help. Just try each stick individually. Do you get the same level of whine on both sides or only on one side ?
Mark

[John Clarke]

I guess you have swapped over the main speed controller outputs to prove the problem is always on one particular motor drive unit.
Or the problem switches sides, that being an electrical problem.
Yes, you'll have reverse control, but it would prove it's either an electrical or mechanical fault,

[Matthew Whiteley]

It is definitely noise coming from the motors. I will take apart the lower glacis this weekend, remove the sprockets and final drives and have a look to see if anything is binding.
I tried driving the M3 with the upper deck on and the turret but that made the binding much worse.
I will post again after I do the necessary surgery lol.

Thanks again for all the support.

Matt

[Matthew Whiteley]

yes, both sides bind. I was wrong thinking it was just the one side.

[Mark Heaps]

Hi John,
actually it will not. It will just point us in the direction we need to go. If it is forward of the motion module it could be electrical or mechanical
That would be the next step in the fault-finding.
Mark

[Mark Heaps]

Before you start stripping the mechanical parts, we should establish whether it is a mechanical problem, which I doubt from what you have previously reported, or an electrical or electronic problem.
Disconnect the electronics and connect each motor in turn through a switch directly to the batteries. If whine when switched on then yes, mechanical. If no whine and vehicle moves okay then electrics / electronics.

[Adrian Harris]

The support desk from the electronics designers have said they would never make that noise, so it is as Kian said probably the motors.

Putting the tank on the tracks make a significant difference to the load on the motors compared to running it suspended.

I wouldn't recommend wiring the motors directly to a battery, as the initial surge will put a huge load on the drive train and the motor mounts.

Adrian.

[John Clarke]

Your right Mark, I meant checking the electronics. Still it is an easy test just to see if the fault swaps over.

I'm with Adrian with the direct battery connection test, unless you use a low voltage such as 6 volts dc which is how I checked Chieftain gearboxes and final drive.

If it is binding on both final drives now, strip down, clean out and a light touch of fine emery paper might clean off any burrs on both spur and final gear teeth. (don't go mad) Look out for witness marks.
If grease has been used in the final drive housing make sure it's not packed in too much, allowing some air space.

[Matthew Whiteley]

Hi guys,
I didn’t see the replies and went ahead and stripped it all down.
I added some grease inside the final drives where there was some evidence of rubbing.
The motors went back in nice and secure.

I made sure there was suitable space between the sprockets and final drive as there was a touch of rubbing there.

I tested it without tracks and the right motor sounded nice and powerful. The left motor sounded a bit quieter. Could be me.

I put the tracks on and it runs better but the motors still make the binding noise.

I’m beat after all that surgery so tomorrow I’ll re read your posts and try switching or testing the voltage if I can rustle up a voltmeter.

Again, thanks so much for all the interest and tech advice. I’m glad I’m not alone out here in the Colonies.

I’ll keep putting in the elbow grease, I would love the M3 to run smoothly.

Matt

[Matthew Whiteley]

Hi guys,

I couldn’t rest so I found my voltmeter and tested the connections to the motors. The right motor gets just over 18 volts at full throttle and the left motor gets just over 17 volts at full throttle. I tested the blue and yellow wires from the Motion pack that connect to the motors.

The Armortek box says it’s getting 25 volts from the batteries.

Are the volts too low or should that be enough to power the motors?

Thanks,
Matt

[Mark Heaps]

Too low for me. With an H-bridge MOSFET circuit driving the motors, I would expect a maximun of 2 volts drop between battery voltage & motor voltage at full PWM.
Do you have the ability to try out a different transmitter ? Could be a transmitter setting reducing the demand.
Mark