GG1 in large scale?

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jscarmozza
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Re: GG1 in large scale?

Post by jscarmozza »

Thanks for the information and advice Big Dave, after reading your reply I watched a few u tube videos on the subject ...it's not for me. John
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makinsmoke
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Re: GG1 in large scale?

Post by makinsmoke »

Don't forget about JB Weld. It has several versions
with varying hardness and cure temps, as well
as one or more containing metal filler versus plastic.

I have been using it against sheetmetal then
plan on a skim coat of plastic filler if necessary.

It takes longer to cure, but in applications where
there is little bending and flexing I believe it to be
superior to Bondo if you are willing to work with it.

It will flow as it cures, so if you are able to set your
piece horizontal it will do a good job of filling.

Additional coats can be applied as necessary.

And, a magnet will stick to it!

Take care,
Brian
jscarmozza
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Re: GG1 in large scale?

Post by jscarmozza »

The chassis on the prototype GG-1 was cast and had reinforcing flanges in high stress areas, in order to duplicate the look on my fabricated chassis, I brazed on steel strips and ground them to match the prototype contours. To fill and smooth out the welds I used metal filled epoxy as Brian suggested; after grinding and sanding the chassis looks like it had been cast. Building this without plans has been difficult to say the least, lots of trial and error on everything; for example, I have four sets of marker lights, two fabricated, one machined, and one cast, I'm going with the cast set. Some time ago in another chaski discussion someone posted prototype plans, I printed them and they've been very helpful, without those plans I couldn't have made the trucks, whoever that was thank you. I did a trial fit up of half the articulated chassis and one truck to see if anything interfered, just about everything did, it took over a month to eliminate what I identified and I'm sure there is more. That being said, I appreciate the response to my questions, I wish I had known about chaski long ago. John

p.s. Brian, I'm going to use your method, thanks for replying.
jscarmozza
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Re: GG1 in large scale?

Post by jscarmozza »

I completed the brakes on the A-unit of my GG-1 chassis and the entire system is bound up tight. I made each part with a sliding fit, but I'm sure there are misalignments, particularly in the brake shoe hangers. Should there be a little 'jingle' in the hangers and linkage? Your thoughts and advice would be appreciated. John
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Pontiacguy1
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Re: GG1 in large scale?

Post by Pontiacguy1 »

Start by loosening all your bolts just a little bit and see if it will move then. If so, you're pinching everything together when you tighten it down, and you'll need to add some clearance in a few places.
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slsf1060
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Re: GG1 in large scale?

Post by slsf1060 »

jscarmozza wrote:I completed the brakes on the A-unit of my GG-1 chassis and the entire system is bound up tight. I made each part with a sliding fit, but I'm sure there are misalignments, particularly in the brake shoe hangers. Should there be a little 'jingle' in the hangers and linkage? Your thoughts and advice would be appreciated. John
It looks as if the GG1 is upside down in the picture. When you right the locomotive wouldn't the axle boxes sit further up in the frame and move wheels away from the brake shoes?

BTW - Nice work!
Darren McNeely

and the sons of Pullman Porters, and the sons of engineers,
ride their father's magic carpets made of steel.

www.swlsonline.org
jscarmozza
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Re: GG1 in large scale?

Post by jscarmozza »

Pontiacguy, I loosened the hanger bolts on the chassis connections, I didn't think they were as tight as they turned out to be. That freed the assembly a lot but it still didn't work. I then loosened all of the turn buckles and the rear shoes moved but the front shoes didn't. I hope there isn't anything wrong with my design! What isn't apparent in the photo are the three bell cranks that I relied on to change direction of the pull on the actuating rods. On the head end of the chassis under the truck is a push solenoid connected to a vertical bell crank that reverses the action and pulls on the rear brake actuating rods; at thr tail end of the chassis and rear brake actuators are two horizon bell cranks that reverse the action and pull on the front brake shoe actuators. This is somewhat true to the prototype, but it's a lot of motion and I hope I can adjust the turn buckles to get all of the shoes to operate. That being said, I think I'm going to replace all of the nuts with ny-lok nuts so that I can keep the joints free without concern that the nuts will back off, do you think nylon washers would help rather than the steel on steel that's at all the contact surfaces now?

Slsf1060, the chassis is upside down in the picture, the journals are in the extreme up position since I didn't install and connect the suspension. Your comment gave me an ut-oh moment, I didn't take the vertical travel into consideration when I started on the brakes! Everything turned out ok, the travel to the bottom extreme position is about 3/16" and there's no interference. The journals ride on coil and leaf springs and the suspension it rather stiff and stays close to the lower extreme position. I don't think the original builder intended to put as much detail into the chassis as I did. I tried to stay true to the prototype by adding leaf springs, walking beams and brakes.

Thanks for you comments and insights, John
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Re: GG1 in large scale?

Post by jscarmozza »

I put the project on the back burner for a few months, I was disappointed in the poor function of the brakes and the multiple interference points I discovered just about everywhere. After looking at the brake system for a long long time, the lights went on and I thought to myself 'how could you be that stupid'. When I made the brake hangers I made them in a way that automatically tightened the hanger when the hanger support was tightened, but if I left everything loose it caused the brake hanger supports to rack and bind as well as introduce more lost motion than the throw in the solenoid. Finally I realized I couldn't have a free shaft through the hanger support, so I soldered the hanger shaft to the supports so they can be made up tight and solid to the frame while the brake hanger on the other end of the shaft could be mounted freely using a ny-lock nut. I haven't reassembled it to try it but I think it will work.

I also cut out the frame cross supports and replaced them with thinner members. I had been grinding and milling the original 5/8" thick cross members every step of the way in order to get things to fit and something always rubbed or bound up, finally I had enough and I replaced the 5/8" members with 3/16" thick ones and the problem was solved. Sometimes I wonder why I didn't replace them sooner, but I guess I thought each time I hacked at them the problem was solved, anyway it's done right now.

I want to get the A and B chassis units done and joined so it can be fitted to the body frame and the body work can be started. I was planning on using rivets to fasten the sheet metal body to the 3/16" body frame, I made a mock up and it turned out nicely, I hope it works as well on the body with all the curves. The pilots and pantographs look to be a little tricky, I have some plans and lots of photos so I hope to get them right when the time comes.

Lots of mistakes and redoes, I'll post some pictures as I make progress with the project. John
jscarmozza
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Re: GG1 in large scale?

Post by jscarmozza »

I just completed a test run of the 'A' chassis unit on my 50 ft diameter test track, it appears that I got most of the bugs out of it. I was gratified to see that the equalized suspension actually worked, and that the rocker swing link in the truck also worked. I took part in a discussion about swing links in a different post, my design isn't the best but it seemed to function ok. I think the addition of the lateral springs on each side of the pivot plate helped to stabilize the rockers and bring them back to center when exiting a curve. I thought the springs may have been too strong, but once the unit left the short section of straight track and entered the curve, the rockers healed over and the spring just about fully compressed. I attached the pilot for the first time and there may be a clearance issue between it and the truck on a tighter curve. It was ok on the 25 ft radius, there was about 1/16" clearance, but that may be a problem on tighter turns and switches.
My biggest disappointment is the brakes, after a lot of reworking and refitting, they still don't work, and I don' think they ever will. Poor design on my part. I didn't appreciate the function of equalized linkage and made my linkage straight and square; hence, the lost motion in the various components used up all of the travel. And, the bell crank that I used to reverse the direction of pull so that I could apply the opposed shoes didn't really function. If anyone has drawings of a brake system for two opposing shoes on each wheel I'd really like to see them. The brakes on the 'A' unit involved many hours of work over the past year, and I'm afraid it was all for nothing (should have asked for help).
I'm going to proceed with the remaining work on the 'A' unit and get going on the 'B' unit bypassing the brakes for the time being so that I can get the chassis assembled and fit and finish the body. Any help on the brakes will be appreciated. John
ccvstmr
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Re: GG1 in large scale?

Post by ccvstmr »

John,

Don't know what you were doing with the brake system you devised...but I helped a friend complete a 1.5" scale GG-1 several years ago. The loco was started by a long deceased club member. My friend purchased the loco (what there was) from the family and went forward. Eventually, the loco was sold.

Brakes were a concern with the electric drive. Regenerative braking can only do so much...and it's not intended to bring a loco (let along a train) to a complete stop. I was asked to come up with something. I chose a rather simplistic approach. Why reinvent the wheel? I've built a number of Tom Bee trucks with his brake system. I've used that concept to equip trucks from other manufacturers. There was no reason why it couldn't work in the GG-1 application.

Rather than apply 2 sets of brake shoes for each driver...we opted to install pairs of brakes shoes between the #1 and #2 axle...the #2 and #3 axle...the #4 and #5 and between the #5 and #6. These were basically opposed piston cylinders so braking effort was equalized. Retraction springs were installed to pull the brake beams/rods back when the air was released (for a straight air brake system). Here's a few photos...

The 1st photo shoes the pair of brake beams. Brake shoes were cast in resin with a piece of timing belt used as a brake pad imbedded in the casting (could be easily changed by gluing in a replacement). Brake cylinders were alum tubing. Brake pistons were made of black nylon with "U" cups used for the seals. Brake hangers were made from 1/8 x 1/2 hot rolled steel...slightly bent, but made to fit in a slot on the back of the brake shoe to hold the shoe in alignment (somewhat) with the wheel tread. Pneumatic tubing was cut at time of installation.
xIMG_0260.JPG
The next photo shows the brake shoes in relation to the driving wheels.
xIMG_2163.jpg
xIMG_2163.jpg (24.16 KiB) Viewed 13869 times
In the last photo...this is a bottom view of the drivers. Aluminum channels were attached to the frame cross braces...a cotter pin inserted thru the channel and top of the brake hanger supported the beams and shoes.
xIMG_2164.JPG
Hope this helps illustrate one possible working brake system for GG-1's and gives you an idea how you can move forward. Carl B.
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jscarmozza
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Re: GG1 in large scale?

Post by jscarmozza »

Carl, I'm having trouble posting pictures today, if you look back a few pages you'll see a photo of the brake rigging that I used. All mechanical linkage activated with an electric solenoid. I was trying to stay true as I could to the prototype with the various details on the chassis, but I discovered that since painting the chassis flat black, you can't see any of the parts that I worked so hard on making! That being said, I think I'm going to sacrifice form for function with the brakes. My project is 1" scale, I don't think I could fit your configuration into my model, but I may be able to use your idea in a different configuration between the brakes on each wheel where I have 6" to work with as opposed to the brakes between wheels where I have less than 1" between hanger centers.
Thank you for taking the time to respond to my request for brake system options, I like your idea. I'm going to start researching how to use it in my project. I have a little 12 volt tire pump that has been in the trunks of the last 4 cars that I've owned and never used, that may be my source of air! I'll post from time to time on my progress. Thanks again, John
jscarmozza
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Re: GG1 in large scale?

Post by jscarmozza »

The tire pump idea didn't work very well, but I did find a source of mini air compressors and components at viair.com. I'm converting the mechanical brake system to a pneumatic system. I made a couple of prototype cylinders and they worked amazingly well. John
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