Securing a gear on a shaft without pressing it on

[matthewsx]

Come on! Hammering it on is so Mickey Mouse! And so is gluing it on.

Work out a way to secure it mechanically.

Modern adhesives are actually very good at this type of thing. The main bearings in my racing engines would typically be an interference fit with heating an aluminum case to receive the bearing. When these bearing races became oversize it caused all kinds of problems for what was essentially a lawnmower engine modified to run at 8500 rpm. The loctite bearing retaining compound solved the issue and allowed me to rebuild many engines that would have otherwise required a replacement case.

If you do some research you'll find out that many modern cars and other products have adhesive in places that used to be welded. The adhesive process is faster, cheaper, and more reliable, otherwise manufacturers wouldn't be doing it. The science has come a long way in the past few decades and it's used in many mission critical applications where only welding or mechanical fasteners were used in the past.

Cheers,

John

 

[Latinrascalrg1]

IMHO the best option would be a Heat/Freeze (Expanding/contracting) slip fit and I would recommend using a heat gun and a small can of "compressed air" keyboard cleaner for the freezing medium. The compressed air keyboard cleaner is filled with liquid nitrogen and if you spray the can when its upside down you will get a very very cold nitrogen spray that will FREEZE anything if sprayed long enough! So you quickly spray the shaft after you have the gear preheated and ready to slip on the shaft as soon as you spray it down with the compressed air can. The gear will easily slip onto the shaft but will quickly seize onto the shaft once the opposing temperatures mix so be sure to have things lined up or it may be a bit difficult to adjust once set.

 

[matthewsx]

As I understand it the biggest challenge here is that customers with different levels of skill and/or attention to detail need to perform whatever operation is needed. In this case using a retaining compound, especially if it can be pre-applied.

JMHO,

John

 

[ezduzit]

Modern adhesives are actually very good at this type of thing. The main bearings in my racing engines...

Two completely different applications: a bearing fit and a drive gear.

It would be naive to think that:

a) you could provide such a precisely machined bore that would produce a light press fit on every application out there, unless you had the actual mating part in hand.

b) similarly depend on an amateur DIY mechanic to successfully glue on a drive gear.

 

[matthewsx]

Well, I think the OP will need to test out the available options and make a determination as to what works best.

 

[alloy]

After listening to everyone here I think the adhesive is the way to go. Heating the gear to expand it would end up with someone under the car with a propane torch and highly flammable transmission fluid everywhere. To freeze the shaft to reduce its size would take a lot. Shaft is 1.410 and attached to a large clutch drum, sticking out of a transmission. I would trust people on here to have enough common sense to be safe, but literally speaking we are a select few.

There is another company doing mods like this, the difference is they use a new casting and I modify the existing one. They have you press the gear on. They say the shaft should be 1.410 and that's what my sample measures. But I can't rely on a mass produced part to be the exact same diameter all the time.

I realize I'm relying on people with questionable skills and attention to detail to clean a shaft, put a wire wheel in a drill, scuff up the shaft and apply the adhesive and slide the gear in place, but I don't believe I have a choice. If I go ahead with this. And I am going to do this.

I think what I'll do is machine the gear, prep the shaft, install the gear using the 609, let it cure and they stick it in my oven at 350 degrees and see if it holds.

Thanks everyone , I sincerely appreciate all your responses.