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Discussion Starter #1 (Edited)
I have a machine that needs an obsolete brass auger gear. I cannot find it anywhere on the internet.

The details are over here on this other thread...
http://www.snowblowerforum.com/forum/craftsman-snowblowers/87633-how-dismantle-536918200-5hp-22-a.html

So here's my question...

Is it feasible to switch to a totally different gearbox with a new matching impeller shaft if the gear ratio is approximately the same?

Here's my thinking....If the shafts are the same diameter and the same length, and if the auger gearbox has a similar gearing ratio (plus or minus 10%) then I naively expect that it should work fine.

The speed of the auger is determined by the gearing ratio which, in turn, is controlled by the number of teeth on the gear. Anything within 10% or so seems like a reasonable substitution.

Am I missing something?


Edit: A second question:
This gear seems to have the same general specs...

2 inch outer diameter
3/4 inch inner diameter
22 teeth

Could that "just work" or might I need to get a matching impeller shaft (I'm thinking the designed "slope" of the teeth may be different)

 

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AFAIK the auger and all the internals between the correct model machines interchange with the exception of the housing itself along with the auger shaft being different widths.

536.918100
536.918200
536.918202
536.918700

Those are the ones I've had and do interchange between the 20" and 22" units. I've taken the whole housing from one and swapped it to another a couple of times. There's also some that are painted black and gray that also look identical and also should swap but I don't have the model numbers for them but I think they all begin 536.918xxx.

I have an extra 20" housing you can have for parts if you can arrange your own shipping. I won't have time for a while to take it apart as it's very cold here lately. I do not know if the auger rakes are rusted on or not, I bought the machine for parts and used what I needed (I think I got that one for the axel and handlebars), saved a few pieces and scrapped out the rest.
If you can wait till it warms up some, I can see about disassembling the thing but as cold as it is, it will be a while before I can do it.

I typically watch for non-running machines I can use for parts. Most I've bought for about $25 or less, running or not. If you can find one for that kind of price, grab it. It's worth it just for a parts unit. Especially if it's got a working motor, those 2 shaft motors are difficult to find and worth keeping one on the shelf if you find one.
 

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If the good gear that you have has the same diameter, thickness, # of teeth, hole and keyway size as the stripped one, it should fit. Same number of teeth and diameter should give you the same ration as you had before.

The only possible issue, as you said, is the pitch of the gear teeth match the worm drive spiral on the impeller shaft. The actual cutting geometry, angle of the teeth, depth of cut have to match up with the worm on the impeller shaft.

If you are using the OLD gearcase, that should work with the new brass gear if its the same size. If you are going to use a different gearcase with the original impeller shaft, then there are more measurements to consider, bushings, any possible roll pins and their position etc.
 

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If you get a used gear, try to get the worm gear too. That way they can be installed as a set. Kind of like putting a new cam shaft into an engine and use old valve lifters, can cause extra wear.
 

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Discussion Starter #5 (Edited)
AFAIK the auger and all the internals between the correct model machines interchange with the exception of the housing itself along with the auger shaft being different widths.

536.918100
536.918200
536.918202
536.918700

Those are the ones I've had and do interchange between the 20" and 22" units. I've taken the whole housing from one and swapped it to another a couple of times. There's also some that are painted black and gray that also look identical and also should swap but I don't have the model numbers for them but I think they all begin 536.918xxx.

I have an extra 20" housing you can have for parts if you can arrange your own shipping. I won't have time for a while to take it apart as it's very cold here lately. I do not know if the auger rakes are rusted on or not, I bought the machine for parts and used what I needed (I think I got that one for the axel and handlebars), saved a few pieces and scrapped out the rest.
If you can wait till it warms up some, I can see about disassembling the thing but as cold as it is, it will be a while before I can do it.

I typically watch for non-running machines I can use for parts. Most I've bought for about $25 or less, running or not. If you can find one for that kind of price, grab it. It's worth it just for a parts unit. Especially if it's got a working motor, those 2 shaft motors are difficult to find and worth keeping one on the shelf if you find one.
Thanks for the offer to let me have parts. I can certainly wait for warmer weather.
It sounds as if you may have the worm gear I need if it's from either a model 100 or 200.
I would certainly buy that worm-gear if you have it.



Thanks also for the model comparisons.
This may be more detail than anyone's brain can handle (mine included) but I just looked up the parts for all four models and discovered that....

The 100 and 200 models are identical to each other except for the axle. Presumably the difference is simply 20" versus 22".
However, all the gearbox parts are identical (but unavailable). My model is one of these.. it's the 200.

The 202 and 700 models are identical to each other in all respects.
Gearbox parts are available for these however the parts numbers are not the same as the two previous models.

It turns out that the bearings and seals are identical for all four models which means that the shaft diameters must also be identical
for all four otherwise the seals and bearings wouldn't work.

As a table, the whole thing looks like this (as an image because cut-n-paste does not work for tables)

The worm-gear part I need is colored RED 50223
The worm-gear part I found earlier is colored BLUE 51405MA

I'm worried that the gear I found on the internet may or may not be an exact match even though the inner diameter (0.75"), outer diameter(2") and tooth count (22) are the same.
I say this because the input shafts have different part numbers and therefore the geometry of the spirals could possibly be different... maybe... I don't have the specs to be certain.

EDIT: If I start searching for any other models that take the same worm gear that was on the internet (which may not be what I need)..
the information explodes exponentially. It's probably not worth going down that route because all the part numbers change yet again.
One such model would be the 536886260.
 

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Discussion Starter #6 (Edited)
If the good gear that you have has the same diameter, thickness, # of teeth, hole and keyway size as the stripped one, it should fit. Same number of teeth and diameter should give you the same ration as you had before.

The only possible issue, as you said, is the pitch of the gear teeth match the worm drive spiral on the impeller shaft. The actual cutting geometry, angle of the teeth, depth of cut have to match up with the worm on the impeller shaft.

If you are using the OLD gearcase, that should work with the new brass gear if its the same size. If you are going to use a different gearcase with the original impeller shaft, then there are more measurements to consider, bushings, any possible roll pins and their position etc.
Yes... it's that small doubt about the cutting geometry that worries me.

If the worm gear was an exact match, I would have expected it to show up as a replacement part number somewhere.. but it doesn't.

One option I thought about was maybe getting the worm gear and the input shaft (aka impeller shaft) as a matched pair.
That might work if those parts fit into my gearbox.
But the cost for doing that is way more than the blower is worth.

My best bet right now is to wait to see what HCBPH finds in his parts bin when the weather warms up. Sounds like he probably has the piece I need.
It bugs me to give in on a machine just for the sake of one bronze gear... It's a bit OCD... just don't know when to quit.
 

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Hopefully it will warm up some in a week or two. I need to move the car if I need to use the hydraulic press and that doesn't handle slick anything well. Regardless you can have what I find, all I ask is postage.

Too bad you aren't around here, here's another 5hp 22" for $25: Craftsman 5hp 2 stage snowblower

Not pretty but doesn't have to be in order to be a parts machine.
I remembered the black and gray ones that are the same, IIRC they all start off 536.882xxx and parts from those interchange with the red and white 536.918xxx ones. Get a 5 hp of either, so far I think only something like the handlebars are different.
 

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Discussion Starter #8
Hopefully it will warm up some in a week or two. I need to move the car if I need to use the hydraulic press and that doesn't handle slick anything well. Regardless you can have what I find, all I ask is postage.

Too bad you aren't around here, here's another 5hp 22" for $25: Craftsman 5hp 2 stage snowblower

Not pretty but doesn't have to be in order to be a parts machine.
I remembered the black and gray ones that are the same, IIRC they all start off 536.882xxx and parts from those interchange with the red and white 536.918xxx ones. Get a 5 hp of either, so far I think only something like the handlebars are different.
Yep.. that's the parts machine I need... It's got the twin shaft engine too.. that would be useful for a Craftsman TRAC machine I have that was repowered with a Clone. I haven't figured out how to flip the transmission... so reverse gear is forwards and forwards is reverse.

I am so psychologically invested in getting these little machines working, maybe I should just move to Minneapolis and be done with it ;-)
 
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