Nagano Mini-excavator

Could you just make one?

How about taking the pieces of the pinion to a machine shop and see if they can repair it for you? If not, maybe they can make you a new one? Art

Making an unavailable gear::

The cutter was shaped to fit an undamaged tooth space in the broken original.

That one is aluminum. How about Stressproof or 4140 Prehardened?

jsw

Better to break the pinion than the ring for one thing. Make two and have an available spare.

But neither Stressproof nor a machineable hardness of 4140 is going to make much of a pinion. Those things typically are loaded like crazy. If they're through-hardened (the weakest heat treatment for a highly loaded gear, but the most common), they're generally too hard to machine with ordinary tools and machines.

Is this a straight-tooth pinion, or a spiral or hypoid? If it's one of the latter, there aren't many shops that could make it, without a Gleason or Liebherr gear generator, which means a custom gear maker. Not cheap. Even if it's straight, it's not a heck of a lot easier. The teeth and the gullets are tapered from one end to the other.

I'm wondering if the size of the set is close enough to that of a truck ring and pinion that you could make that fit, or machine either one a bit to fit.

That would be a little complicated.

The pinion has two ground bearing surfaces plus a spline on one end and the gear on the other end. Being of Japanese manufacture, I assume both the gear and spline are metric. I am looking at reparing the existing pinion shaft, but want to explore finding a replacement first.

A previous owner had problems with this part, and a half asses repair he made to the gear teeth further complicates any repair. I am in the process of measuring the (30? inch) ring gear to calculate the size of the pinion.

John

Does this machine need to work hard to make money or can the operator afford to baby it?

jsw

Perhaps a last resort, but I just had a couple gears that need to be duplicated quoted by these folks.

One part was a non-standard (extended pitch) 8DP pinion on the end of a shaft, with two bearing seats and a locknut thread, made from 4150 with induction hardened teeth. The price was about $900 for two pieces, including an engineering charge to measure and document the original gears.

By no means cheap, but it didn't seem unreasonable to me.

I really don't know. I suspect the owner is willing to make some compromises as the machine is now essentially useless.

The owner suspects that the first repair failed after the operator tried to move some material sideways; pushing it with the bucket by rotating the cab/bucket arm assembly. This heavely loaded the rotator pinion and caused the repair to fail.

John