looks good to me. keep the heat treat down on the 4340 ... no more than 1/4 hard (something like 125ksi), maybe normalised (90ksi).
I was advised by the gear machine shop to avoid hardening the 4340 too much as well. 300/340BHN (I assume this is approx 32-27 Rockwell C?) is what they specified in a quote.
maybe shotpeen the relief cut ?
This is interesting, I never investigated this treatment. Is it costly?
currently there are two pieces ... the gear and the shaft, yes?
Two parts, yes, a gear and a stepped shaft.
how about shrink fitting them together ?
The gear comes keyed from the factory and fully hardened. We'd avoided machining it.
maybe put the relief cut in the shaft ??
What was the OEM shaft material?
Original shaft material was probably 4140 or 4340 but it would have been machined from the normalized stock and not received any heat treatment. Would a heat treatment have been appropriate for this?
Was the junction a very small radius or even a corner?
Junction was a fairly sharp corner, with a radius no more than that of the cutting tool.
If the gear had a larger diameter square and flat face and could be clamped hard against a similar feature on the shaft the fillet would not be (would not have been) subjected to bending. I'd still incorporate a proper radius
I think I understand what you're describing, it was a very tight space which didn't allow any extra vertical clearance.
Does the gearbox get precisely located in order to set the backlash between the pinion and the trunion?
Yes, it's adjusted with threaded screws and locked down with a firm clamp.
How is the perpendicularity of the reducer hollow-bore that the step shaft nests in?
Admittedly, not that great.
Is the baseplate grouted?
Yes.
What are you rotating? Is the rotation bi-directional?
4,000 lb load, 180deg back and forth in 10 seconds, every 90 seconds or so.
What is the radius in the step shaft fillet? Why is it so small? Can you chamfer the id of the spur gear and use a larger fillet radius?
It's sharp from the cutting tool. Small chamfer already on the ID of spur gear, we were avoiding any machining on the spur gear so that it would be a drop-in replacement for wear but that would certainly have helped our fatigue.
Was this arrangement used in order to avoid purchasing a rotary indexer?
Back and forth motion or budget may have negated the use of a rotary indexer.
Did you follow the trunion bearing manufacturer's recommendations for thickness/flatness of the surface that the trunion bearing mounts to?
As best as possible.
That big guard over the reducer looks like it limits the cooling of the reducer - what does it do? ....
A protective kickplate. Personnel frequent in the area.
-Kevin
