Shaft to Gear Connection 3

[lucky-guesser]

I am working on a functioning prototype that is very similar to what the final result will be. You can see in the attached image, my gear laminates that would be braze welded together, are drilled through so that a small roll pin can fix them to the shaft during assembly. Some time later the caffeine kicked in and I realized what a nightmare this hole will be to drill. By that point I had already designed the entire rest of the assembly around this drive shaft, so my options are limited on what changes I can make. The task at hand is that I need a way to attach these gears (will likely be a single thicker gear in production) using some method that can be done during final assembly with hand tools. Using a key seems easy, except I have a bearing directly on either side of the gears so the key can only be cut as wide as the gear thickness, and I've never seen it done like that. 5/8 dia shaft, gears are roughly 1/4 thick total.

If a redesign is in order then it is what it is but after the latest department meeting everyone liked this design, minus the obvious flaw, so I am hesitant to change more than I have to.

 

[SnTMan]

lucky-guesser, you out there?

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[mfgenggear]

ya I hate it , bad as bad can get, any one ever see a gear box blow up. due to a component failure. i have, the entire box is destroyed. we have no idea of the fit form or function, so suggestions are mute. what are the torque, RPM, stress and strain values.
in addition this must be a sloppy low RPM thing because gears are never the exact same size, tooth thickness PD runout, tooth to tooth error you name it.

 

[mfgenggear]

also to add what is the risk management of this component. what types of rejection would be caused by this design. dollars amount of scrap, manufacturing issues, and line stops due to lack of parts. I would ask for help in the design, start over, while still on paper. now it's lost time, but you will thank me in in the future. if this design gets made what are the issues.

 

[lucky-guesser]

mfgenggear
"also to add what is the risk management of this component. what types of rejection would be caused by this design. dollars amount of scrap, manufacturing issues, and line stops due to lack of parts. I would ask for help in the design, start over, while still on paper. now it's lost time, but you will thank me in in the future. if this design gets made what are the issues."

As of this moment this is a one off prototype that only needs to work a few times. The final product will be low torque, relatively low RPM, and should it fail it would be a minor inconvenience to the consumer.

SnTMan
"lucky-guesser, you out there?"
I had laid out a few constraints and limiting factors that most people ignored in their suggestions so I quit paying attention to the thread for a while.

 

[mfgenggear]

if this design does continue due to cost, and time, assemble the two gear. as a detail. as suggested, rivet together line hone the hole, machine the od of shaft for close fit. shrink fit is an easy process, dip the shafts in liquid nitrogen, use all precautions by the manufacturer for safety, heat the gears to -50 Deg, of the tempering temperature , look at the calcs for thermal expansion, and shrink properties. then rework the gears after assy to shaft to make them exact. a slight machining to clean up. gear hone, or skiving. grinding is easier but more expensive.

 

[mfgenggear]

problem with brazing it's not always repeating, the clearance between parts has to be correct, to obtain capillary action. there might be lack of penetration, of the braze. so I believe this is vacuum brazing and not acetylene brazing. which can be more problematic in a production environment. because of not following procedures. and lack of NDT testing. brazing used and is common industry practice, but there are strict specifications, and procedures, with NDT testing to verify good braze penetration.

 

[MintJulep]

I had laid out a few constraints and limiting factors that most people ignored in their suggestions so I quit paying attention to the thread for a while.

Welcome to the internet!

Can you share your chosen solution and how it worked out?

 

[KevinK2]

I have been surprised to see a simple shrink fit to fix a gear to a shaft in a high torque application for an automotive transfer case. A very simple, legitimate solution already mentioned by others.

Shot or WEC peening the shaft for fatigue resistence could be considered:

https://www.mdpi.com/2075-4701/12/4/642