Another broken truck

[MeanTT]

Do we have any suspicion that perhaps the issue is the gear lash or incorrect shimming? Perhaps the gears are binding or getting extremely hot (I know, a very unlikely event and higher temperatures should increase ductile responses to shock)?

The pictures with these broken pinions look catastrophic, and I can't see how it could happen unless the type of metal used is something akin to a cast iron (2.1 percent carbon with a lot of slag). I know that sudden impacts through a metal can cause ductile metals to respond in more of a brittle fashion because the particles don't have a chance to "absorb" the shock. However, any steel gears should certainly survive the lower power that this rigs transfers, and if not, an alloy with more manganese or less carbon should certainly help. We aren't talking about a 20 pound rig or 6S 1/8th scale power here.

Open question to Vaterra, is it possible the wrong alloy was used as compared to what was ordered in the purchase order? That would explain a lot of these failures, and I could certainly see a Chinese manufacturer either (i) making a mistake, or more likely, (ii) hoping that you never found out that the alloy is a cheaper variant than what was ordered. Those specifics should all be in the PO anyhow.

[redxz]

I think it would be helpful if over in the Pinion Gear thread people reported their kit number with failed gears.
We maybe could see a trend.

[mgputer]

Originally Posted by MeanTT

Do we have any suspicion that perhaps the issue is the gear lash or incorrect shimming? Perhaps the gears are binding or getting extremely hot (I know, a very unlikely event and higher temperatures should increase ductile responses to shock)?

The pictures with these broken pinions look catastrophic, and I can't see how it could happen unless the type of metal used is something akin to a cast iron (2.1 percent carbon with a lot of slag). I know that sudden impacts through a metal can cause ductile metals to respond in more of a brittle fashion because the particles don't have a chance to "absorb" the shock. However, any steel gears should certainly survive the lower power that this rigs transfers, and if not, an alloy with more manganese or less carbon should certainly help. We aren't talking about a 20 pound rig or 6S 1/8th scale power here.

Open question to Vaterra, is it possible the wrong allow was used as compared to what was ordered in the purchase order? That would explain a lot of these failures, and I could certainly see a Chinese manufacturer either (i) making a mistake, or more likely, (ii) hoping that you never found out that the alloy is a cheaper variant than what was ordered. Those specifics should all be in the PO anyhow.

These gears aren't machined or cast. They use a machine with molds and compress medal powder into them. They then heat them in a furnace which binds the particles.

A bad heat treating process or improper settings on the amount of pressure used on the molds can cause the parts to be weak.

So it appears the issue is probably a bad batch or 2 from Vaterra's supplier or every person in here would be complaining.

my 2 cents

[BJoe]

X2 mgputer