# Need advice on keyway for train wheel



## SE18 (Jan 28, 2017)

Hi all,

I've got three 2-foot gauge kiln cars, one of which I'm going to turn into a locomotive for my railway. I've dissassembled them to clean out the gunk in the bearings, as they've been sitting for a decade in a farmer's field rusting away.

The problem I see, in turning one of them into a locomotive is the way the wheels are fitted to the axles. They are lightly pressed over an upset axle that has some gouges to friction hold it. In fact, they're so lightly pressed that I pulled the wheels off by hand. It's a spindle axle, meaning the whole thing turns.

The idea is to belt or chain drive the axles. The torque produced would likely make the wheels slip on their axles.

The first idea that came to mind is to create a keyway in the axle and wheel and key them all in place. I have a tiny hobby mill and a 9" SBA lathe and 2 drill presses. The axle could easily (I think?) be milled for the keyway but the wheel would be harder. 

Perhaps the wheel could be mounted on the drill press and a broach could create the keyway by manually running it in and out (of course without any power to the DP). 

A second idea I have instead of a keyway would be to turn some collars to fit on the insides of the wheels. Holes for set screws to the axle and then to the wheel could be drilled and tapped.

the wheels are just shy of a foot in diameter. The diameter of the axle is 1 3/8" and the hole in the wheel is about 3.5" deep. 

Thanks for any ideas!


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## Bob Korves (Jan 28, 2017)

The nominal keyseat size for a 1-3/8" shaft is 3/8".  I don't know what your "tiny hobby mill" really is, but it may well not be enough to cut long key seats in steel.  As for the wheels, their key seats would need to be broached with a 3/8" keyway broach using a hydraulic press or other means.  You did not speak of what kind of motive power you have in mind, and how much total weight it will be pulling, on what types of grades, which might also change things.  You will also need adequate brakes...


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## SE18 (Jan 28, 2017)

Thanks; I've got a 20-T press I'll use then and shop for a 3/8" broach. It will likely be diesel power. A friend of mine who builds locomotives for a living will be supplying some sketches for me. The grades are unknown as I plan to retire in a couple years near Harrisonburg VA where my daughter lives and build a RR. I already stockpiled 2,500 feet of rail. It will be primarily an agricultural railway hauling crops and timber (for fun of course too). There's a short stretch of track in backyard and tracks in 2 car garage for workshop.


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## Tony Wells (Jan 28, 2017)

Ideally they would be splined to fit. Without a shaper it becomes more complicated, but you can do the job with a broach, as long as you are willing to machine an indexing slot in your broach bushing. You would not have to use as large a keyway, since the force would be distributed among the splines.  And of course, milling the male splines on the shaft becomes trivial. 
No larger than it is, a single keyway would transmit power sufficiently, but on power transmission components, splines are very common. I would consider this method superior in the event of any thin areas in the wheel hub, since as I said, the splines would be smaller (more shallow and not as wide) as a single drive key. It's more work, obviously, but an alternative that may have advantages.

Nice project. I have about 3 acres to play with.....maybe a retirement project. I am pretty sure I won't quit the shop when I do fully retire.


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## Reeltor (Jan 28, 2017)

Thank you for sharing your wealth of knowledge.  While I love RR's I would not consider building one; with that said the information on key-ways and splines will be squirreled  away for future use.


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## rgray (Jan 28, 2017)

I'm liking that tracked work table. Might be limited use around here for me in the winter, but then there are things that would be real handy to do outside in the winter also. Torch , plasma cutter and heavy grinding come to mind. Doing those in the snow would be piece of mind.
Very cool railroad!!


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## T Bredehoft (Jan 28, 2017)

Splined shafts and hubs are alright, but unless SE18 is going to replace either the shafts or the wheels, it's pretty hard to put splines in both and have an interference, a number of keyways would do the job, but that's a LOT of keyways.


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## chips&more (Jan 28, 2017)

If the size of the hole is the same as the shaft OD diameter, you cannot spline it, sorry, nada. One or the other would need to change size so the male and female spline would marriage. Keyway is about the only option. You are talking a lot of horsepower transmission. So a good robust fit would be in order…Dave


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## SE18 (Jan 29, 2017)

Thanks for your advice. If any of you are thinking of doing just a small shop railway, you can create track panels that are easy to move. They're steel ties. I use panels b/c I got a citation from our HOA telling me to remove the track in the driveway or else pay stiff fines etc etc (another reason I'm eventually moving). So I set the panels down when I need to push my workshop outside. I'm currently building a railcar dedicated to carrying a furnace for blacksmithing and it will also feature a crane. I'm also building a turntable that will go in the backyard soon.

BTW, each of the workshop cars has four trailer male mounts and 4 trailer jacks to act as outriggers, to keep the cars from moving on the rails when working and the trailer jacks can also be used to level the work area. I had one of these 2,000 lb cars derail and the trailer jacks were used to slide rails under to re-rail.


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## easymike29 (Jan 29, 2017)

Maybe this?



Gene


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## Jason Annen (Jan 29, 2017)

On the real ones, there is no key or splines.  36" wheel, roughly 9" bore with 8 to 10 grand fit.  They push on with 150 to 200 tons.  We do them from time to time.  Some wheels are 40" and 42" on the newer ones.

Jason


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## Glenn Brooks (Feb 23, 2017)

+1  what Jason said.  Probably the easiest and most effective way is to turn new axles with a slightly larger diameter and press the existing wheels on with an interference fit.  Or You can put the new axles in the freezer to shrink them half a thou and heat up the wheels to red hot on the BBQ and slip them right on, if you get the axle tolerances within a thou or two. 

I've just done something similar with old,  double flanged turntable wheels - the old 1" roller bearings were rusted into a solid mass, so turned 2 1/2" shafting down to fit the wheel ID.  Then pressed the axle blanks into the core of the wheel, and am now furthe turning down the axle  ends to fit 1" OD flange bearings.  Here's a photo or two.

No reason you couldn't make new wheel sets the same way...




Glenn


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## Joncooey (Feb 23, 2017)

Just my 2 cents, if all else fails, another option is using a shear-pin.  Bore the axle and wheel hub and install a bolt or roll pin.  Crude but effective and easily made and serviced.


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## owl (Feb 23, 2017)

Old school way is with a file.  If you are only talking about 2 wheels, and your mill is capable of cutting the axles, I would guess that less than an hour of careful filing would complete the other part of the keyways on the wheels.


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## ewkearns (Feb 23, 2017)

I've cut many keyseats using a lathe and boring bar. Grind a HHS cutter to size, slot using the crossfeed for depth of cut and carriage handwheel to drive the cutter.


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## 12bolts (Feb 23, 2017)

You could press it on with a shrink fit and then use a scotch, (dutch) key to lock it

Cheers Phil


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## Bi11Hudson (Feb 24, 2017)

There are several approaches available. To me, without actually seeing the project, I would press the wheel back on and drill a small hole in the joint between the end of the axle and the hub of the wheel. Starting at 1/8 inch and working up to maybe 5/16'. The 5/16" could be offset in the future with a square key but a round key will stand up to a lot of force. When you figure out how to make a good cut on your mill, and a broach for the wkeel you can make a square key if you needed it. Maybe a light knurling on the axle to give a "force fit" if it was loose. Didn't sound like it was, but loose on one job is tight on another. Depends on the service...

A round key was often used by railroad people a hundred or more years past. It wasn't right, but it worked well enough to get the job done. If it were me, I would use a roller from an old bearing as a pin and leave a little sticking out to get to later if I needed it off. There are several ways to do this key-ing, this seems to be the simplest and quickest so you could get back to the right-of-way debate.

By the way, I have some 7-1/2" stuff that I'm working on now and again. The small scale stuff (H-O) now, that's where most of the work is these days as I age.

Lots of alternative ideas floating around here, perhaps you will find the optimum one to use. Good luck with the old equipment, that stuff is a bear. An additional thought that night pay off someday is the way I make wheels. Too small for your stuff, but ya never know. Take a disk brake rotor and cut off the disk, leaving just enough for a flange. The hub would have to be large enough to make a wheel, of course. May save your butt one day.  Bill Hudson NMRA 2125(Life)


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## 12bolts (Feb 24, 2017)

Otherwise known as a scotch key Bill


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## kwoodhands (Mar 1, 2017)

12bolts said:


> Otherwise known as a scotch key Bill



Bill, I've used Scotch keys for years to hold wheels in place. I did not know the method had a name til I read your post.
First time I used it was to hold locomotive wheels in place. Loctite was supposed to do the job but one wheel continually slipped. I was going to try to cut a keyway in the hub and axle. I set the parts up in the mill and first bored a 1/8" diameter hole  1"deep thru the hub and axle . It occured to me that a roll pin or any rod would work well to keep the wheel from turning. I then reamed the hole to .126 and pressed the rollpin in. Did not need Loctite as the rollpin went in tight. I then repeated this with the rest of the wheels.
mike


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## SE18 (Mar 2, 2017)

Thanks. The Scotch or Dutch Key sounds good. The filing might take a lot of work since there's 3.5" to file (unless just a partial keyway is made. Lathe and boring bar would work except the diameter of the wheel is several inches larger than the 9" swing of my SB9A lathe. Broach and press sounds good. I'll have to think about all the options.

That turntable wheel looks pretty cool btw


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