Great Northern GE 44 ton Center Cab Electric restoration

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Glenn Brooks
Posts: 2930
Joined: Mon Nov 10, 2014 1:39 pm
Location: Woodinville, Washington

Great Northern GE 44 ton Center Cab Electric restoration

Post by Glenn Brooks »

Finally got started restoring my old GNRR center cab yard goat. The loco has been out of service and laid up in dead storage going on 40 years or more. Needs a bit of attention.
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This is a home built 1/4 scale (12” gauge) version of a GE 44 toner, operated by the Great Northern Railway as a yard switcher in their Everett, Wa freight yard in the 1950’s and 60’s. This unit was home built by the original owner in 1968, following his retirement from the Northern Pacific RR after 40 years of service in steam and diesel. I have an old newspaper article that represents the loco is a model of one of two early day diesels he operated in the Everett yard, prior to retirement.

The GN only owned two such locos, road numbers #98, and #99, built 3/43 and 6/46. Renumbered #50 and #51 in photos below.

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This second loco (photo below) was still in service in 2010, displaying the orange and black “Empire Builder” livery of the 1960’s GN era. As my loco displayed vestiges of the same Empire building color scheme, Iam going to go out on a limb here and say this loco is the original prototype that my miniature engine is based on.
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My plan is to power the loco same as the prototype- outfit each truck with an electric traction motor and wire them in separate circuits, with one truck providing light duty service, and both trucks used for heavier loads.

Unlike the original 44 toners, this will be all electric. I’ll run both traction motors with one 48 volt battery pack. The motors originally came from a Clark forklift drive chain.

Last fall I rebuilt the trucks and journals, and cleaned up the body for this part of the restoration. Once I’ve get the electrical system sorted out, I plan to lower the height and widen the center cab, add 18” or 20” to the length of the cab, and add running boards, foot plates and proper front and rear platforms. And, sand blast and paint everything - to give the loco a much better looking profile and proper livery.

So far the biggest problems have been researching the proper components to build a dual 48volt system, and working out how to mount the traction motors and two-stage reduction gearing in both hood ends. I owe a big shout out to all the folks who responded to my previous threads about electric motive power and tractive effort.

So today started the actual build. Made a plywood and cardboard 1:1 mock up to locate the traction motor and locate the 6:1 (two stage) gear reduction. (See pics below.)

My plan is to mount each motor and chain drive on a 3/8” plate atop each truck. The plate will act as a bed to stabilize the traction motor and intermediate gear axle. Everything will be elevated above the bolster, but be bolted down to the truck frames with mounting brackets. The traction motor will sit inside each hood end, but be independent of the frame and body. In this way, the motor and drive chain will stay aligned and swivel with the truck.

Here is the existing truck, with the original chain driven gears mounted on each axle.
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Below, the Mock-up sits atop the truck. The round cardboard cylinder to the right in photo represents the actual size of the 7” OD traction motor. (Much lighter to work with than the actual motor (75#!). The round disk on the left represents a 7” (3:1) gear mounted on an intermediate shaft, running on pillow blocks. A secondary chain and gear will run down from the intermediate axle to the drive shaft, to provide a further 2:1 speed reduction.

A big design issue here is the traction bed (with the motor and gearing, etc) must mount above the bolster. And have room to swivel within the hood end, as the loco navigates curves and dips in the track. Hence the need for risers to elevate the machinery above the bolster...
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Couple of other oblique angle views of the design.
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Experimenting with a spring loaded intermediate drive axle. I need to somehow compensate for vertical changes in chain slack, caused by movement of the truck suspension and the drive wheel. Thinking a pivoting, spring suspended intermediate gear might be a solution.
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Below: Rear view- showing motor body first, secondary gear reduction placement in the background.
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Next step: fit truck and mock-up into the hood end. Then fab and mount two sets of the actual mounting brackets and motor mounts onto the drive beds for both trucks.


Glenn
Moderator - Grand Scale Forum

Motive power : 1902 A.S.Campbell 4-4-0 American - 12 5/8" gauge, 1955 Ottaway 4-4-0 American 12" gauge

Ahaha, Retirement: the good life - drifting endlessly on a Sea of projects....
Glenn Brooks
Posts: 2930
Joined: Mon Nov 10, 2014 1:39 pm
Location: Woodinville, Washington

Re: Great Northern GE 44 ton Center Cab Electric restoration

Post by Glenn Brooks »

Couple of minor tweaks to the traction bed, and risers, and looks like it’s good to go. Wacking away unneeded bits of plywood with a jigsaw and hole saw certainly speeds up the design process by orders of magnitude.
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Rounded the corners and moved the vertical riser posts inboard a little bit to enable a wider turning radius. Time to fab up all the bracket bits and pieces.
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Here the base of the intermediate gear bracket will have a slot cut in it to accommodate the chain passage to the drive axle. Also bolt down slots to enable tension on the chain.


Below, inside the hood end; looking down on the traction plate.
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rounding the edges of the traction plate ensure plenty of clearance (and turning radius) inside each hood end. The actual traction plate and the intermediate gear bracket will need to be bolted in place after the truck is installed under the bolster.
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Fortunately 12 inch gauge railroading gives you plenty of room to work!
Moderator - Grand Scale Forum

Motive power : 1902 A.S.Campbell 4-4-0 American - 12 5/8" gauge, 1955 Ottaway 4-4-0 American 12" gauge

Ahaha, Retirement: the good life - drifting endlessly on a Sea of projects....
Pontiacguy1
Posts: 1566
Joined: Thu Apr 26, 2012 10:15 am
Location: Tennessee, USA

Re: Great Northern GE 44 ton Center Cab Electric restoration

Post by Pontiacguy1 »

Just a bit of personal experience that I want to share with you... But I don't think you're going to be happy with what happens to your locomotive if you have a chain that goes around an axle and has a near-vertical pulling force on it. I had a small locomotive I built that was like that, and when trying to start a very heavy load, it would try to lift that axle up off the ground, and then as it was pulling forward, it would bounce that axle just a bit and would then lose traction. you had to be extremely careful starting a big load on a grade, or the locomotive would bounce up and down slightly and lose its footing. When it was in a hard-pull while starting a load, you could actually see the entire locomotive squat down slightly as the force from the chain lifted most of the weight off that one axle. I re-designed it with two idler gears that made the vertical chain turn 90 degrees right before it went to that axle. Solved the bouncing and axle lifting problem, and the locomotive was a much better and easier locomotive to start a train with or run at low speeds. No more squatting down when in a hard pull. Once you got up any real speed, the vertical chains didn't seem to matter as much because you weren't in such a hard pull. That's just my own experience with it, so do with that what you will.
Glenn Brooks
Posts: 2930
Joined: Mon Nov 10, 2014 1:39 pm
Location: Woodinville, Washington

Re: Great Northern GE 44 ton Center Cab Electric restoration

Post by Glenn Brooks »

Pontiacguy, Good catch. very happy you mentioned that. I’ll go see if I can reverse the position of the motor and the chain drive.

Any idea what the ideal angle of pulls is against the axle? And does a serpentine belt versus chain make any difference, with angle of pull?

Also, did you incur any additional penalty with extra friction or resistance with the idler gears?

Thanks
Glenn
Moderator - Grand Scale Forum

Motive power : 1902 A.S.Campbell 4-4-0 American - 12 5/8" gauge, 1955 Ottaway 4-4-0 American 12" gauge

Ahaha, Retirement: the good life - drifting endlessly on a Sea of projects....
Pontiacguy1
Posts: 1566
Joined: Thu Apr 26, 2012 10:15 am
Location: Tennessee, USA

Re: Great Northern GE 44 ton Center Cab Electric restoration

Post by Pontiacguy1 »

I just ordered some plain bushing idler sprockets (because they were smaller in diameter), then bored them out to accept two radial ball bearings. Ideally, you want there to be very little to no angle, so that the force is always front and back, and the chain doesn't tend to get a whole lot looser or tighter with vertical travel. I think i fixed it so that the chain basically looked like the Lexus L, coming down at about 30-35 degrees off of 90, and then making the turn to go straight back to the axle.

All I noticed is that it was a lot easier to start a load on a grade. Otherwise, it seemed the same. I don't think two extra idler sprockets, on ball bearings, and about an extra foot or so of chain will be noticeable.
rkcarguy
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Joined: Tue Aug 22, 2017 10:33 am
Location: Wa State

Re: Great Northern GE 44 ton Center Cab Electric restoration

Post by rkcarguy »

Glenn, some food for thought.
If you are going to use a spherical bearing type action on the bolster with the bearings on standoffs taking the load, the truck is going to pivot fore'/aft to any track condition and stay flat with relatively even weight distribution regardless of the torque of the motor pulling up on the axle. A tensioner is only needed to keep the chain tight as the axles move under the springs. If you are using a standard flat bolster (which it appears in the pics above), you may have issues as pontiacguy1 suggests.
Glenn Brooks
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Joined: Mon Nov 10, 2014 1:39 pm
Location: Woodinville, Washington

Re: Great Northern GE 44 ton Center Cab Electric restoration

Post by Glenn Brooks »

Ryan, I think what Pontiac guy has experienced, is highly likely to happen with my first design- the chain drive is basically centered, 90* over the journal. The vertical chain load with large torque at start up, likely will be enough to lift the drive wheel up off the rail, reducing traction. Potentially enuf to disrupt the initial start up. As is, Although the truck remains stable, the axle can easily move upwards 1/2” or more with a little bit of force.

I looked at it this afternoon, and It’s a simple fix to just switch positions to the opposite ends of the mounting plate. This will impart a better angle of pull between the drive pulley chain and drive wheel. This will require an idler pulley for the chain to clear the bolster, then angle upwards to the drive pulley. But, it’s a small change.

Iam still concerned a bit about running in reverse, as reverse torque loads come to play on the chain drive. But worst case, I’ll just call one end the front, and treat it like a traditional go forward, front end design.

Glenn
Moderator - Grand Scale Forum

Motive power : 1902 A.S.Campbell 4-4-0 American - 12 5/8" gauge, 1955 Ottaway 4-4-0 American 12" gauge

Ahaha, Retirement: the good life - drifting endlessly on a Sea of projects....
Pontiacguy1
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Joined: Thu Apr 26, 2012 10:15 am
Location: Tennessee, USA

Re: Great Northern GE 44 ton Center Cab Electric restoration

Post by Pontiacguy1 »

No matter if you have that spherical bearing for your bolster, it will still likely do this anyway. What was happening was it was compressing the spring over that axle. The weight on all of the drive wheels was the exact same, because the weight transferred from the one axle to the others as the chain pulled it up. This could cause other problems too, since during a hard pull you'd have one axle with a lot less of the locomotive's weight on it. When it compressed that spring like that under a hard pull, then it would start loading/unloading and make the whole thing break loose. It could be several things that would cause it to do that: Uneven track or a rail joint, going through a switch, surging or non smooth power transmission through the chain, trailing load shifting suddenly, etc...

What I'm trying to say is don't have your drive chains trying to compress your suspension springs when you are under a load. Have it routed so that the power transmission chain pulls front and back, and doesn't affect the load on any of your axles, whether under power or not.
rkcarguy
Posts: 1730
Joined: Tue Aug 22, 2017 10:33 am
Location: Wa State

Re: Great Northern GE 44 ton Center Cab Electric restoration

Post by rkcarguy »

Here's my setup. I'm planning on having an idler/tensioner placed on the backside of the chain going from the hydraulic motor to the axle. So it won't be a perfect 90* "L", but will be a lot better than a vertical pull on the one axle. Think this will be ok?
The bracket assembly is going to be purely bolted in, so I can change things around or change the drive type all together later if I need to.
I really want to avoid having the motors down in the trucks, as it's going to get really tight in there with the disc brakes and I don't want my motors down in the weeds, snow, or wet weather as I plan on putting my RR to work in any weather.
S12truckhyd.jpg
Pontiacguy1
Posts: 1566
Joined: Thu Apr 26, 2012 10:15 am
Location: Tennessee, USA

Re: Great Northern GE 44 ton Center Cab Electric restoration

Post by Pontiacguy1 »

I've seen some that pulled at a 45 degree angle, and it didn't have that tendency nearly as bad, although it was still there somewhat. Think of it like this, because sometimes you can't do things exactly the way you want to: The closer to horizontal your pull/pressure on your axle is from your drive chain, the better off you are. If it can't be 100% straight, try to make it as close as you can. Having a drive chain that is pulling 20 degrees off of horizontal will be better than having one that is 45 degrees. the one that I had pulled at about 75 degrees, so not far from vertical, and it was terrible in a hard, slow pull like when you would have to start a big load, especially on a grade. A couple of plates and a couple of idler sprockets put in there, and it was sooooo much better. If your axle is rigid in the frame, ie, it doesn't have any suspension, then you can easily pull straight vertical and not have any problems.
rkcarguy
Posts: 1730
Joined: Tue Aug 22, 2017 10:33 am
Location: Wa State

Re: Great Northern GE 44 ton Center Cab Electric restoration

Post by rkcarguy »

Makes sense. I will give what I have planned a try, maybe insert some solid polymer "springs" inside the rear coil springs. The sprocket on the main driven axle is a 30T and it's rather big, unfortunately adding a tensioner won't change the chain angle very much. If it ends up hopping and having problems then, I will relocate the hydraulic motors. (Sorry for thread hijack Glenn).
Glenn Brooks
Posts: 2930
Joined: Mon Nov 10, 2014 1:39 pm
Location: Woodinville, Washington

Re: Great Northern GE 44 ton Center Cab Electric restoration

Post by Glenn Brooks »

Ryan, No problem. Whole point of these threads is to document best practices. There are always several ways to solve a problem - it’s good to know the various approaches.

I like your approach of anchoring your jack shaft/ spur gear on the vertical plate attached to your end frame. Particularly if one needs to suspend or float the other end to counter flex in the chain caused by the suspension. Thinking about adopting it to my build and plywood mock up.

one possible design issue: BDD has previously recommended setting the driven pulley’s out next to the drive wheel, not in the center of the axle. Apparently applied torque works better at the end of the axle, next to the drive wheel.

Iam looking at that same issue right now- as my drive pulley is more or less centered between the wheels.

Also debating about pre loading the drive pulley assembly with springs, as you mention. It might be good to accommodate chain slack by springing the drive gear like an idler. As you show, thinking of pivoting the rear side of the pulley assembly, and floating the other end on a spring- thru bolted to truck frame to preload the whole assembly. Hopefully some one will comment how important this may be.

Pontiacguy, Here is my updated “Plan B”. I’ve taken your comments to heart and come up with this possible method to mitigate axle movement. What do you think?

When moving the drive gear off nadir, I couldn’t get chain clearance because of the bolster and the body frame member.

So positioned the drive gear in the center of the truck, to drive both axles, not just one. This creates equal legs on all three sides.

Seems perfect!

- lower leg of the chain/belt will pull horizontally. So should mitigate axle rise.
- provides equal torque in either forward or reverse. Pretty important for a center cab, double ended switcher!
- no clearance problems, or chain slack angle problems with the vertical mounting position.
- room to add a larger diameter drive sprocket! I can add up to a 10” pulley if needed! 10:1 gear reduction with super low rpm and high torque!
- perfect center to center distance for standard Gates cog belt and pulley system.

Thinking of calling this, my Elegante’ design.

Here’s a sketch and basic positioning on my mock up.
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And couple of photos - blue masking tape represents the chain line...
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Real happy, so far!

Glenn
Moderator - Grand Scale Forum

Motive power : 1902 A.S.Campbell 4-4-0 American - 12 5/8" gauge, 1955 Ottaway 4-4-0 American 12" gauge

Ahaha, Retirement: the good life - drifting endlessly on a Sea of projects....
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