Great Northern GE 44 ton Center Cab Electric restoration

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rkcarguy
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Re: Great Northern GE 44 ton Center Cab Electric restoration

Post by rkcarguy »

I don't want to use one of those brake straps. Have heard bad reviews of the friction material on those being gone in a couple days from some of the train mountain guys. For a parking brake it's probably ok. I already have brake shoe kits laser cut out for the rest of my rolling stock, but the locomotive will be getting disc brakes that are "always on" and the air cylinder will release the brakes. I can't chance having a 4-ton runaway with the grades I have on my property.

I thought of going with some drum brakes from a small motorcycle, but by the time I mess with all that it's as much work as disc brakes and discs simply work better.
Glenn Brooks
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Re: Great Northern GE 44 ton Center Cab Electric restoratio

Post by Glenn Brooks »

Wouldn’t put to much stock on the 1.5” scale experience at TM. The locos are all quite small, and designed to be well crafted models, with miniature brake parts; not small working commercial engines. So will have excessive wear when subject to commercial loads and continuous operation.

I do like your idea of small compact automotive disk brake systems. These small cars are typically the same weight and load capacity as 1/4 scale locos. I should think you would need to install them on all axles to be effective. Or at least one axle per truck.

Also, food for thought, the unlined friction shoe design on the Ottaways have worked in commercial service since the 1950’s. And the friction brake repairs we did last year on the 36” NG GE 44 toners on the Hawaiian Railway in Eva replaced simple brake shoe castings and brake liners that had been in heavy service since 1943. I think the key for miniature train brakes, is to size it for the appropriate level of service.

I plan ongoing with the traditional friction brake design and see what happens.

Glenn
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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
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Re: Great Northern GE 44 ton Center Cab Electric restoration

Post by Glenn Brooks »

Making some progress building out the first drive truck. Decided to go with all chain rather than drive the jack shaft with a gates cog belt. The gates belt gears are horribly expensive and the belt drive must be rigidly under tension to operate properly. So no room for slack as the axles move up and down with the suspension system. So all chain it is.

Machined and fabed two idler bracket and studs for the idler gears. (One set of parts for each truck). I bought the idler gears on line, only had to turn the studs and spaces, etc.
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After I decided to make all the parts for both trucks, it was easier and less time consuming to turn multiple parts, single point the treads, etc, all in one pass. So here are the last two idler studs turning down to size (5/8” OD). This is some high grade, hand me down shafting from another live steamer. Not sure what carbon content, but it’s been hanging around for years with very little rusting. Turns beautifully and leaves a superb finish. Iam thinking C1144 stress proof maybe.
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Then aligned the idlers with the drive axle sprocket, and welded in place.
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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 »

Yesterday, also welded the four base plate supports to the truck frame, and positioned the jack shaft and drive chain. Looks like everything aligns perfectly. More importantly, the chain tension appears to be within tolerances. I’ve been worried about to much slack in the chain between the idler pulley and drive sprockets. However, my multiple measurement attempts seem to have been successful in locating the idler studs in the correct position to tension the chain correctly. Woohoo, as my daughter would say.
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Next step- fab up the motor mount and mill some slots to adjust the jack shaft tension
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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NP317
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Re: Great Northern GE 44 ton Center Cab Electric restoration

Post by NP317 »

Nice progress, Glenn!
RussN
rkcarguy
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Re: Great Northern GE 44 ton Center Cab Electric restoration

Post by rkcarguy »

Looking good Glenn. #50 or #60 chain?
I'm trying to understand that big top plate, you have room for that to pivot inside the box cab body?
Glenn Brooks
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Re: Great Northern GE 44 ton Center Cab Electric restoration

Post by Glenn Brooks »

Ryan,

It’s #50 chain. Originally I thought it was #60 and ordered some, but nope. It’s #50.

Yes, the plate fits nicely inside the frame and body. Allows the truck to swivel around a 15’ radius. Also the body height is fairly tall, so plenty of vertical clearance. The one design limitation is the top plate is the only way to mount everything in (on) the existing truck, because of small diameter wheels, and the short truck design.

I think I could have mounted the motor directly on the axles if I had used 9” or 10” wheels. But that would have made it a complete redesign and new build- which probably would not have worked out.

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....
rkcarguy
Posts: 1730
Joined: Tue Aug 22, 2017 10:33 am
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Re: Great Northern GE 44 ton Center Cab Electric restoration

Post by rkcarguy »

Ah ok I see, motor diameter larger than wheel diameter, gotcha.
If you have problems with the industrial chain stretching, you can use motorcycle #530 chain on the #50 sprockets it has less stretch, can be bought in 0-ring and X-ring varieties, and has a considerably higher strength. In my years of "mechanical" play, I've seen a lot of premature wear because the chain stretches quickly, "point loads" 1-2 teeth on the sprockets, and quickly wears them as well. Your electric motor is going to make a ton of instant torque, so I'd suggest some RK or DID gold motorcycle chain.
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 restor

Post by Glenn Brooks »

Today, Working to build up the motor mount. Seems like the standard EV rebuild style is to fab up a 1/2” or 3/4” motor mounting plate to bolt to the front of the motor, and a lighter supporting plate to hold the rear. Then bolt or weld the mounts to the frame.

This means cutting a donut hole out the center of the plate for the knob that holds the bearing in the center of motor end plate, then accurately locating 4 holes around the edge, to accept the mounting bolts.

Once the plates are finished, I’ll fit and weld them to 1/4” 3”x3” angle iron and bolt the whole assembly, with motor, to the big truck mounting plate.

To start with, I used a plasma torch to rough out the center hole, and shape the curved top radius. Then ground off some of the heat affected zone with my handy little 4” disk grinder. Finally, after a lot of fiddling with centering and aligning the plate on my rotating table, milled the center diameter with a 1/3rd degree taper (.013” slope offset) and finished off the top edge of the plate.

Very happy, that the plate fits snug around the motor end plate casting - good to a couple of thou! Not bad for architecting my design with permanent marker on the left over plywood mockups, and sketching the mounting plate design on graph paper.

I was able to hold accuracy to around .003” by punching my key center and tangent points on the plate, and locating these points with a nice little laser pointer I bought a year or two ago. I can split a center point divot with the laser, so I feel confident I can find centers to within a thou or less, if need be. Very handy little gadget.

The last step, is to locate and drill four mounting holes on the plate to coincide with the existing holes in the motor end cap. Decided to make up a set of four transfer punches to mark the hole locations. These are precisely the same length. I inserted into the existing motor casting, fit the mounting plate up against the tips of the punches, and turned the plate a quarter turn. This method left a scratch mark on the blue layout die on the backside of the plate for three of the four punches. The end of each scratch mark should indicate the center of each hole.

So now I’ll drill the three holes, run bolts in to tighten down a bit, then sort of lever the plate to locate the fourth.

I suppose the proper Engineering Method would have been to triangulate and precision measure the bolt circle. But Iam not much good with 3 dimensional geometry.

I do plan on mounting the plate on the Rotab and confirming the bolt circle before I drill out the holes. Good double check...

Then, repeat, and make three more plates (2 motors = 4 plates total) using this one as a template.
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 »

Bit by bit, just now finishing up fabricating the motor mounts. The mount (pics below) will bolt to the business end of each motor, and take most of the torque. The rear mounts will stabilize the tail end of motor. Haven’t decided yet if I want to drill and tap bolts into the rear end cap, make some kind of end clamp, or just support the rear end of the motor with the ID of the plate. Leaning towards some kind of screw tensioning clamp, welded to the rear mounting plate. Don’t think I will do through bolts, as forklifts do not require this level of rear support with these motors. As they are entirely dependent on the front motor mounting plate bolted to the front of the motor.

Certainly open to suggestions or new ideas!

On the front end, I initially located and drilled mounting holes to bolt the plate directly into the existing bolt holes around the rim of the motor end cap- using the smallish 1/4” bolts that affix the end cap to the round motor housing. Then made up the dogs shown below. I like these a lot better. They will be welded to the mounting plate to form a permanent fixture to hold the motor in place. They mate up with the actual 3/8” bolt holes pattern that originally held the motor to the forklift frame. Proven and stout! So Iam going to weld in place and call it good.

Used 3x3 angle iron for the feet, 1/2” plate for the engine bracket, and 3/4” x 3” flat bar for the dogs - with all the excess steel whittled away on the mill.

Here are the two motor mounts and feet, waiting for the welder to show up.
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Layup and milling the mounting dogs.
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As it turned out, this workholding didn’t do so well. The end mill pulled the work up into the quill a bit, producing a poor fit over the plate and mounting casting of the motor. So re worked each piece to correct height by holding each dog in the large Machinist vise, with a clamp on the end to make everything rigid.
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Finally, all the bits and pieces bolted together so the welding crew can come in and fire up Mr. Sparky to melt some rod.

Using the Rotab, ended up milling a slip fit, less than .003” clearance, between the plate ID and the motor casting. So the bolts don’t have to take all the engine torque.
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Happy as a clam how this turned out. Worth the extra time and effort to make this fit, so far...

Glenn
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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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NP317
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Re: Great Northern GE 44 ton Center Cab Electric restoration

Post by NP317 »

Looking good, Glenn.
If those are brushed motors, be sure to service the brushes and commutators before putting them in service.
I learned those lessons maintaining the huge 600 V. traction motors on the Seattle Center Monorails!
RussN
Glenn Brooks
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Re: Great Northern GE 44 ton Center Cab Electric restoratio

Post by Glenn Brooks »

Thanks Russ, I stripped down one motor early on and cleaned up the commentator. It has newish brushes already. Wouldn’t hurt to do the same with the other one- actually it did hurt. The dissemble and re assemble was very painful. Not much room to slide the brushes out of the way. But it spins like a top...

Here’s the final assembly of the first truck. Decided to secure the rear engine mount by drilling a six hole bolt pattern to match the pattern in the end cap. The photo below shows only 3 bolts temporarily holding everything together. After painting and final assembly, the rear mount will have 6 grade 8 hex bolts through the mounting bracket and the motor end plate. Very stout. “Skookum” as they say down on the waterfront.

Chain and gears align nicely. Everything fits except for one small exception. One of the countersunk screws in the big mounting plate, stands a bit proud of the surface- interfering with the rear mounting bracket. I elected to put a 3/4” flat bar riser under the engine mounts- to lift the mount over the top of the offending nub. Milled out a slot on the side of the riser to accommodate the fitting. Good to go!

Glenn
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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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