Cotton Brute Restoration 7

This weekend, for the first time in almost 4 decades, the Cotton Brute once more took to the rails.

Old 97 Rail Days, commemorating the wreck of Southern Railroad mail train 97 on September 17, 1903, was held in Danville Virginia at the Pepsi Building on the Danville Science Center campus. The Danville Science Center also encompasses the still active passenger station along what is now the Norfolk Southern line, and has been commemorating the 1903 wreck for the past 20 years.

Part of that event for the past 20 years has been an NTRAK layout made up of modules from 4 of the ten clubs from the Eastern N Lines Partnership; North Raleigh Model Railroad Club, Richmond Area NTRAK, Lynchburg Area N Scalers, and New Jersey Southern N Scale. Lynchburg has since dropped out of the event because they have gone from being an NTRAK club to being a T-Trak club, but we had one member from there at the show.

The first time on the rails was a bit of a mixed bag. Everything seemed to work well (except that the volume, more than adequate in a quiet train room, was woefully inadequate in a noisy show environment) as the Brute traversed the track and then, with no explanation, it coasted to a stop and sat at idle. The horn and bell worked fine, the lights turned on in the proper direction, but the locomotive refused to budge. 

The problem was attributed to an issue with DCC decoders and Back EMF (BEMF) on coreless motors, like the one that powers the Brute. Back EMF measures the current load on the motor and adjusts the actual locomotive speed and engine sounds based on the throttle settings. The idea is to prevent the locomotive from slowing down or speeding up excessively when traversing grades. The difference in the current draw of coreless motors as opposed to traditional iron core motors is apparently significant enough that it throws the BEMF settings off.

The answer was to adjust the BEMF settings to basically nullify the function. Once that was done the Brute operated very well, with the only issues being it's refusal to negotiate tight curves (the locomotive is a little over 7 actual inches long) and the alarming tendency to bottom its fuel tank out on any connecting tracks that were bowed upwards. The layout was modified to accommodate the locomotive and after that it ran just fine.

Pictures and videos have been taken, but not by me. Unfortunately I appeared on the scene Sunday morning just a little late to witness the show, but I did get to see the video and I am pleased to have been a part of the results. Sadly, since I did not get any photos of the loco in operation, I have none that I can share with you. However, I am happy to say that forthcoming articles will have pictures and perhaps a video or two as well.

I was asked what I would charge for this job and I refused payment. I have gotten a lot more out of this project than I put into it, and I told the board if they felt it necessary to compensate me they could come up with a figure and credit me with a donation to the club in that amount.

So what did I get out of this project, you might ask? First, I got a chance to be a part of the history of the Cotton Brute, a locomotive I have read about in NTRAK (now NRail) publications but never thought I would get a chance to see in person. Second, I got a chance to expand my modeling skills. I am very proud of the way the reconstruction of those front steps went, for instance, and having done this gives me the confidence to attack similar tasks that need to be done on a couple of my own locomotives. Last but not least is the pure satisfaction of seeing this behemoth tow a cut of cars around knowing that I was the one that put it back on the job. 

And that is something that is worth way more than the time and small amount of money I spent on this project.

Cotton Brute Restoration 6

 It is done.

I was up early this morning because I worked Thursday night, so Friday I slept when I got home. I did take a bit of a nap last night, but about 1 AM I was wide awake. Perfect time, I thought, to finish the restoration of the Cotton Brute. 

As I mentioned in my last post, the decoder wiring had arrived and the truck wiring was changed but in the process I had lost a tower gear. Fortunately one of the other club members had a donor locomotive, so Thursday on my way to work I dropped by his place to get it. The donor was a U28C, not a U30CG, but the frames are similar and the trucks are identical so it had the gear I needed. The first thing I did when I started was rob a gear from the donor, drop it in place, and install the truck.

And with that done, it was time to proceed.

The channels that I had cut in the weights for the lighting were first deepened so that the decoder wiring would have plenty of room to fit under the shell. The decoder was put in place and the power and motor wiring was run. I cut another channel in the back of the motor weight so that the positive motor wire could be routed where it needed to go without any danger of fouling the driveshafts. I was able to permanently install all the weights after that because the rest of the wiring would run on top of them.

Next the lights, which had been carefully removed and stored away until it was time for them to be reinstalled, were fitted and wired. The purple and green function wires were rolled up and stuffed into a piece of heat shrink so that some other intrepid soul, someone not me, can put ditch lights in later on if desired. I did make a mistake at this step, though. Can anyone spot what is wrong with this picture?

The speaker wires were tucked out of the way so the shell could be test fitted. It went on with no problems and fit down over the weights as it should, so that meant I had the wiring channels cut deep enough to clear. I then took the shell back off and set it aside so that I could install the speakers one at a time to see which one would work best.

Off to the track it went where I programmed the long address with the side number and selected the proper 5 chime Nathan horn. I tested the sound on both speakers and decided on the 50326 because it fit in the space better. During all this testing I checked the lights and discovered that I had wired them backwards. The rear light was on all the time, but the front light only came on when the loco was put in reverse. It ran the proper direction, so everything else was fine. Back to the workbench it went to get the speaker wired in permanently and correct the headlight wiring.

The wires were then taped down with Kapton tape so that they wouldn't shift as the shell was installed. You may notice the speaker wires are not covered with shrink wrap. I had put a piece of tape over the rear light wires to keep them in place but left the speaker wires free when I was swapping out the speakers for testing, so I opted to just put another piece of Kapton over the joints to insulate them rather than grind more away from the weight to allow for the size of the heat shrink. The joints are offset and well insulated, so there shouldn't be any problems with them.

Back to the track it went to verify the lighting, and then I ran it back and forth a few more times to check the motor operation and the prime mover sound. I don't have anything like the proper radius curves to run this loco, but the back and forth testing went well. I haven't programmed in a speed table, obviously, but I'm not overly worried about that. It's a show loco, so if it runs a bit fast that's OK.

The shell has been reinstalled for the last time, the loco was tested with the shell installed to verify everything is working like it should (the speaker is still nice and loud with the shell on), and then it was put on the scales. Even with the weight removed to fit the decoder and speaker it is heavy, weighing in at 22.4 ounces. That's 1 pound 6.4 ounces, only 1.6 ounces less than it weighed when it first came into my tender care. I'm pretty sure it could still pull more than 500 hopper cars, but I doubt it will be put to that test any time soon.

 And now it has been packaged back up and is ready for delivery to President Wallis so that it can make its debut in Danville next weekend. I have taken the weekend off for Danville so that I can watch it go, I'm looking forward to seeing it run for distance and not just up and down a 3 foot stretch of track. 

I will take some pictures and make my final report on the restoration after that.

Oops

 I've lost one of the tower gears for the Cotton Brute. 

I had removed the trucks to replace the wiring. I had used a rather stiff wire and wanted to replace it with the more flexible wire that came in since the last time I updated the blog. I put the new wire on, and when it was time to remount the trucks I only had one gear instead of two. Hours of frantic search proved to be fruitless, this gear has departed for the same place as Micro Trains coupler springs and 10mm sockets.

Fortunately one of the club members has a donor loco that I can scavenge parts off of. Furthermore, it appears as if Marklin, who now owns MiniTrix, actually still has gears for these locos. I have ordered some, but just in case they aren't the right ones, or don't arrive in time, I will be picking up the donor loco tomorrow. If I need to rob a gear from it I can replace it when the ones come in from Germany.

All I have left is to fit and wire the decoder and speaker, so hopefully it won't take me a great deal of time. Either way, I will finish Cotton Brute off this weekend in time for its debut in Danville.

Cotton Brute Restoration 5

 I have three more items to complete on the Cotton Brute and I have a maximum of 19 days to get them done. I want to have the locomotive ready to rock and roll for Old 97 Rail Days in Danville VA, which is happening on the weekend of September 23rd.

Those three items are: fabricating a new fuel tank end to replace one that has gotten lost over the years, hard wiring the trucks in such a way that the wires are not prone to breaking off, and installing DCC.

The trucks were picked to be first because the tank would be much easier to build if the slider pickup on the trucks were eliminated. I had previously tried to just solder a wire between the trucks and the contact pads on the frame, but the wires flexed so much at the solder joints that I feared they would break off eventually.

The trucks are an odd design. There are two geared axles (middle and outer) on each truck and one not geared (the inner wheelset). The dummy wheelset is made of a hideous gray plastic that looks nothing like steel, something that I resolved to take care of while I was there with a bit of steel colored paint. This will do for the outer face of the wheels, but unfortunately nothing can be done for the treads.

The two geared wheelsets have one wheel that is isolated from the axle. Power (actually ground since they are on the left side of the loco) is picked up on the non-isolated wheels and transferred through the axles to the metal body of the truck, which is then fastened both mechanically and electrically to the frame with a metal pin that also holds the truck and idler gear in place. 

Power is picked up on the isolated wheels by way of a slider contact on the backside of the wheel. This contact is a single piece that runs along the bottom of the truck (isolated from the truck frame by a fiber insulator) to the inner end where a finger sticks out to touch a contact pad on the bottom of the locomotive. This finger is the part that had to be eliminated.

The front truck was done first. A hole was drilled in the truck frame and a channel hollowed out to clear the solder joint. Said solder joint affixed a power wire to the contact at the bottom of the truck through a hole in the insulator. The wire fed up through the hole drilled in the truck frame to be attached to the locomotive.

Another hole was drilled in the locomotive frame (fortunately the original part of the U30CG frame, not the depleted uranium tank that joins the two ends) and the wire was fed up through it, leaving a loop between truck and frame to accommodate the truck swing. Once everything was in place a continuity check was done to ensure that the power wire was fully isolated from the frame and that the truck wheels were connected. 

After that the finger was removed and once again the entire circuit was checked for continuity where needed and insulation where not. Once this was successfully tested on the front truck, the rear truck was likewise modified. And with that done, it was time to fabricate the tank end.

The tank end was going to be a challenge because on the Minitrix U30CG that was the donor locomotive there is an air tank affixed to the end..sort of. The only parts of the tank that are actually present are the ends, there is no middle of the tank. This allows the trucks enough room to swing while appearing to be close enough to eliminate any unsightly gaps between the fuel tank and the truck end. This also served to disguise the slider contacts coming from the trucks, which have now been eliminated.

As I was looking through photos of the real-life U30CG however, I noticed that the air tanks were noticeably absent. Likewise, the U30C from whence the U30CG came also had no air tanks. In fact, the only place I found air tanks was on the Minitrix model. 

This, of course, made things somewhat easier. Since no air tank was required, I decided to extend the fuel tank end a bit to reach all the way to the end of the leading truck. The tank end was fabricated from sheet styrene and affixed to the leading end of the fuel tank, then painted Cotton Brute Grey. The existing rear tank (complete with fake air tank) was left alone.

With trucks and tanks out of the way, the next step was installing a DCC decoder. At first the plan was to install a simple Digitrax DZ126 decoder, for which there was plenty of room once the weight above the motor was removed. The idea was to get the locomotive chipped and then think about perhaps installing sound at a later date. But, it was reasoned, why do the work twice?

An ESU Loksound 5 Micro and two speakers were obtained and the decoder loaded with U50 sound files (fun fact, Jim Fitzgerald referred to the Cotton Brute as a U60CG). They were then delivered to me for installation.

At first I had thought that I could simply install the sound decoder above the motor in the same manner that the DZ126 installation was planned, but sadly it is just a bit too tall to fit between the motor and the shell. There is a lot of room under that shell but it is taken up by 11 ounces of cast lead weight. Some of that weight would therefore have to be sacrificed to fit the decoder and speaker.

I picked the locations to coincide with weights that could be completely removed and replaced with styrene shelves to hold the components, but when I weight the removed weights I found they totaled 4 ounces, a full quarter pound. The locomotive initially weighed in at 24 ounces (that's a pound and a half) so with the 4 ounces gone it would still be a hefty 20 ounces, but I really didn't want to cut a full sixth of the locomotives weight out. 

On the other hand, I didn't want to destroy the weights that had been so carefully cast by the locomotives creator, but after thinking about it for a while I decided that the locomotive was unlikely to be converted back to DC once the sound decoder was installed. So, the weights were marked and the cutting began.

I would like to note for the record that all lead weight cutting, filing and shaping was done while wearing a respirator mask, goggles and gloves and my hands were thoroughly washed after each evolution. Furthermore, during the cutting and filing processes a shop vac nozzle was duct taped to the vise to remove the dust. The shop vac that I used is the type that can be fitted with a bag, and one was fitted so that the lead dust could be properly disposed of. Always use caution when working around toxic substances like lead.

In all, a total of 1.3 ounces was removed from the two weights to clear enough room for the decoder and the speaker. A channel was also cut along the tops of the remaining weights for the decoder wires, probably another couple of tenths of an ounce. I will install the decoder and then test it with each of the speakers to determine which speaker sounds best. I had considered installing both speakers, one forward and one aft, but I decided I really didn't want to remove any more weight.

This is where the first major snag was encountered. While ensuring enough room had been made for both decoder and speaker I realized that the decoder doesn't have long enough wires to reach the speaker or rear lights. This is a long locomotive. So now I am on hold until the decoder wire I have ordered comes in.

Two out of three items taken care of means that it was still a pretty productive weekend.