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Lower bevel gear and spindle

Posted: Mon Feb 11, 2019 2:22 am
by chas b
Hi all. I'm putting my MHR engine back together and have noticed something that I havn't seen before. One of the lower bevel gears turns freely on its spindle, the other is too tight to move. Now i've always assumed that these were one piece assemblies and I've never come across this before.
Has anyone got any opinion or experience of this? I'm thinking maybe I should use high-strength retainer to fit the gear to the shaft...

Regards
Chas.

Re: Lower bevel gear and spindle

Posted: Mon Feb 11, 2019 8:57 am
by wdietz186
The gears should turn on the spindles that support them. I am assuming the gears you are talking about are the distribution gears that are driven by the crank and in turn drive the tower shafts and the spindles go between the engine case and the support plate. The spindles should be free to turn inside the gears,look for dirt/grit between the gear and spindle.

Re: Lower bevel gear and spindle

Posted: Mon Feb 11, 2019 10:20 am
by ducadini
Let's take the spare-parts book of MHR on THE site :-D
TAV9 shows the complete bevel factory.
#25 is a press-fit on the primary part of #17 and that is a press-fit on #16.
There is a key to fix position of #17 to #25
It is possible to dismantle them withouth heavy equipment but it should be a tight fit.
Don't want those gears wobbling on the shaft and messing up shimming.
#16 runs in a bush in the cases and in a bearing in the outer support plate.
Shims in action.

Never found any loose parts in that area :shock:

ciao
ducadini

Re: Lower bevel gear and spindle

Posted: Mon Feb 11, 2019 3:03 pm
by chas b
Two different opinions! :) From my own experience I have never noticed this before and in fact the other gear/spindle is tight. It doesn't seem logical to have a gear spinning freely on the spindle, surely the bush and bearing should provide the required movement?

Re: Lower bevel gear and spindle

Posted: Tue Feb 12, 2019 5:55 am
by Gardner
You are thinking right, bearing on each end of shaft, gears locked to shaft, shaft and gears spin as one.

Re: Lower bevel gear and spindle

Posted: Tue Feb 12, 2019 9:44 am
by Craig in France
ducadini wrote:
Mon Feb 11, 2019 10:20 am
Let's take the spare-parts book of MHR on THE site :-D. TAV9 shows the complete bevel factory.<snip>
Yeah, agree: always best to refer to parts by their numbers rather than just a description ... :)

The parts in red are the ones that ducadini is talking about. Me, I thought you meant the 'lower bevel gears' as arrowed in green :? .

Should they be spinning on their shafts? No. Otherwise there'll be no drive to the half-shaft :doh: .

But maybe I've mis-understood ... :er:

Image

Re: Lower bevel gear and spindle

Posted: Tue Feb 12, 2019 10:47 am
by wdietz186
To clarify, Per Craigs parts diagram. The gear[25] and the driven side of the bevel assembly[17] are keyed together so they don't turn independently. That pair of gears, as per all I have had my hands on are a slip fit on the spindle[16]. Yes it is mounted into a ball bearing on the support plate and it does turn when the engine rotates but it floats a small amount when assembled correctly and is free to turn or not. My estimation of the setup is if it was meant to turn with the gear all the time it would have more than a bushing supporting the far end. I know the helical cut of the bevel gear loads the gear outward forcing it into the support plate when running so the spindle is just there to locate the gear.

Re: Lower bevel gear and spindle

Posted: Sun Feb 17, 2019 8:56 am
by andybaggies
One of the lower bevel gears turns freely on its spindle, the other is too tight to move. Has anyone got any opinion or experience of this?
I'd also like to know if there's a definitive answer to this because, yep, I have exactly the same thing on my Darmah. The front pot gears (easily) spin on their spindle and the rear ones don't move an inch. I've tried a few times to gently jar them apart with a rubber mallet but for fear of smacking them too hard it came to nothing. They do seem to be be quite firmly attached.
My estimation of the setup is if it was meant to turn with the gear all the time it would have more than a bushing supporting the far end
And perhaps the gears would also be keyed to the spindle.

Although I've been ignoring this, I must admit I'm of the opinion that they should spin freely on the spindle, and this thread is enough of a reminder for me to try and separate them. Lets see if a daily soaking of plus gas for a week or so will help things.

BTW thread
addresses the shimming of the lower rockers and may prove informative.

Re: Lower bevel gear and spindle

Posted: Sat Feb 23, 2019 9:11 am
by andybaggies
Hurrah :-D I managed to separate the gears from the spindle.

I didn't use plus gas but immersed the complete caboodle in paraffin for two days with the occasional rubber hammer biff as means of encouragement. It finally came loose when I applied a little more pressure by allow a hammer to fall on the spindle, not hitting & only from a height of an inch or so, just letting the weight gently fall and it came loose.

There doesn't look to be any signs of nipping/scoring/seizing up but there was a few dark, what looks like oil, deposits that I suspect are the most likely culprits. And I reckon a little clean up with T-cut and cotton buds should sort them out.

Whether the oil had gummed up when in use or in the time is was laid up I'll never know. One hopes the latter.

Hope this helps Chas.

Andy B