Large Scale Central

Re-motoring a Bachmann 4-wheel Trolley

Modeling Motive Power
#1

I have a couple of locos with the Bachmann 4-wheel trolley power brick under them. The latest is one of the toast-rack trolleys that I picked up from Star Hobby in non-running order. I used to rewind Mabuchi and MRC motors for slot cars, so taking motors apart is not a problem for me - so I figured I could probably find the problem and fix it.

Well, I found the problem - the brush gear on the motor wasn’t connecting with the commutator. However, despite the best efforts of my big gear/wheel puller, I couldn’t get the worm off to get the plastic end cap off and see whether there is a bigger problem. Then I lost one of the tiny, tiny brush springs, despite carefully placing it in a plastic container. Sigh.

Bachmann sells replacement trucks with side frames for $57-ish, plus shipping, so the cost to repair was going to be $65. Way too much for a trolley that cost me $50 and sells used for $80-100. So I went looking for a motor. The end cap has “Kader 881” moulded on it, and we all know who Kader is, so I suspected there might be other applications for it. A bit of googling and I found a note on an HO website asking if the new GBP50 had the Kader 881 same as the Spectrum locos. No idea what he was talking about, but a quick shuftie of the parts dept came up with a replacement HO GP50 motor that looked like mine. For $19.80.

So I ordered one and it arrived yesterday. Postage was another $7 btw so the total was $26.66.

Definitely the same physical type of motor.

There’s some differences around the brush gear so I will probably pull the old worm (careful application of the mini-blowtorch) and the new universal, and swap end caps. Part of the rationale is that I don’t know about the windings in the motor - HO motors are rated 0-12V and Bachmann Large Scale are rated 0-18V. I suspect they are the same motor, and I’ll put the meter on the windings when I get it open.

Stay tuned . . .

Bachmann Hand Car (Gandy Dancer) Motor
#2

Great stuff Pete… just as another member complained about needing replacement motors.

By some Internet research, I was able to find the make and manufacturer of the Aristo GP-40 motors, working backwards from markings on the motor itself…

Let us know…

Greg

#3

Pete Thornton said:

Stay tuned . . .

I will.

#4

This is music to my ears. i’ve got about six of these trolleys, most with bad gears, which I’ve replaced with 3D prints. But I can use a couple of motors. Getting rid of the universals and remounting the worms may be a problem for me too.

#5

should be able to use a puller and a torch, since brass will expand faster than steel.

Greg

#6

Greg Elmassian said:

should be able to use a puller and a torch, since brass will expand faster than steel.

Funny you should mention it. . .

Anyway, to back up a bit. Here’s my wheel/gear puller set to yank the worm off. [I think it was designed for Lionel wheels.]

The wet piece of kitchen towel is to act as a heat sink for the flame. I had already tried to pull it but with no success. Part of the issue is that the puller shaft is too big for the worm hole, so I had to use a small steel pin - which didn’t want to connect firmly with the end of the puller’s pin. So a short piece of tubing was found in the parts box.

With that in place, and the flame applied, there was a small click and the worm came free. No idea what was keeping it - as the shaft was clean I imagine it was some sort of loctite glue.

I had removed the brushes and springs earlier, surmising they were the problem as one was broken. Having got the worm off, it was easy to pry apart the metal tabs holding the end cap in place and pull it off. You can see the bottom brush holder tube is shiny, but the top one is clogged with something. It may have been over-heated and that’s melted plastic, or it may have been a molding issue which meant the trolley never did turn a wheel before I got it!

Anyway, I cleaned it off and poked a metal pin through and all seemed well. I then put the end cap back on my motor, deciding to use it instead of the new one, for 2 reasons: (1) the brush gear has some complicated bits of metal soldered to it for connection to the pickups and (2) I’m still unclear about the 12V versus 18V windings, so I thought it might be better to use the one I had. The commutator looked used, so maybe it had run before I got it and had overheated.

Here’s the endcap and brush holders from the outside. I’m using a flat-head punch to bend the tabs back on the motor case to hold the endcap in place, and supporting the motor on the vice. Note the brush holder - the metal bit, that you can’t really see as it is bent up towards you, is a round tab the is bent over the spring when you have inserted brush and spring in the hole. Not a very good mechanical solution, but the springs are quite light.

This is a brush spring out of the new motor - those screws are the usual B’mann for holding the bottom plate; about 1/4" long.

The springs are very easy to lose - I carefully saved one from the original exercise before I found this motor and now I cannot find it, and this one sprang out of my hand and is somewhere in my workshop along with the first one I lost. Fortunately I ended up with 2 springs so I could replace the brushes and springs…

And that was it. I dug out the old Atlas power pack and connected it to the motor and it runs. $26.60 for a pair of brush springs!

I will bash the worm back on the shaft and put it all together, and take it round to Jerry’s SC&M for track testing.
Oh, and I need to sell it - no room on the shelf for it. It so far cost me $76, so offers around there accepted.

#7

Be careful how you “bash” the worm gear back on. I was trying to heat a washer to friction fit over a steel sleeve on a motor and during the “bash” process, the motor got sloppy from the several hits/pressure becoming basically worthless.

#8

Todd Brody said:

Be careful how you “bash” the worm gear back on. I was trying to heat a washer to friction fit over a steel sleeve on a motor and during the “bash” process, the motor got sloppy from the several hits/pressure becoming basically worthless.

Funny you should mention that . . . As the worms don’t fit completely over the motor shaft, I had the same problem as trying to remove them. I found a small screw that fit in the worm that I had not removed, and that allowed me to tap the worm directly onto the shaft which was supported by the little screw. No heat (or glue) involved. It seems to be pretty secure - time will tell.

#9

After a dental surgery visit I did not feel like doing much, so that was a good excuse for a trip to the workshop!

Once you get the worms back on you can wiggle the motor back into place. The metal tabs have to fit over the slots at the side, and the wires go forward and through a slot (you should probably remember how you removed them! I could have benefited from taking a photo.)

Here’s the flip side. I had to replace one wire, carefully unsoldering it from the motor so the tabs didn’t come off too. The two short wires were trying to break after all the fiddling around. These metal strips provide power to the car lights.

And finally, having got it more-or-less ready to screw together, I noticed the wheel back-to-back wasn’t too inspired. One was correct (1.56", close enough for a thick flange) but the other was about 1.4". So I put the wheelset on the top of the vice and tapped where the axle is with the punch. By the time it was done, I had punched a hole in the plastic disk hiding the metal wheel. And now, as I wasn’t using a drill press, one wheel wobbles. Maybe it did before?

The black wheel insert seems that it will come out with slight persuasion.

#10

The final piece of this, after reflection, is that I think I will swap the whole motor next time. I don’t think the motor windings will be an issue for 12V versus 18V.

The stuff soldered to the brush holder gave me pause:

Any time there are 2 different items soldered to a tag, it is difficult to unsolder and resolder them, as you have to hold all 3 items stationary (tag, wire, contact strip.) To do that and wield a soldering iron almost needs you to make a jig to keep it all together. The wire (to the contacts on top which drive the lights in the trolley) are not robust - I replaced one as I figured it was down to a few strands still unbroken. But it can still be done with judicious use of clamps, etc.
Another good pic before the tabs got bent!

#11

Well, if nothing else, the affair was an informative exercise in the exploration of possibilities.

#12

https://estore.bachmanntrains.com/index.php?main_page=product_info&cPath=68_202&products_id=1491&zenid=8lg95qdr3kdib1g7iduhur2aq1

Or search the eStore for Part No H61206

#13

It looks like getting the universals off the new motors doesn’t look to difficult – cutting disk should do it. Sweating off the worms not so easy. Maybe I should 3D print the worms? I’ll see how difficult designing a worm is.

#14

Dick Friedman said:

It looks like getting the universals off the new motors doesn’t look to difficult – cutting disk should do it. Sweating off the worms not so easy. Maybe I should 3D print the worms? I’ll see how difficult designing a worm is.

Dick, the gear puller is a pretty useful tool. Here’s the one I use: https://www.zoro.com/proto-jaw-puller-j4041/i/G7515286/feature-product?gclid=Cj0KCQjw9ZDeBRD9ARIsAMbAmoaaKC6W-Uk-aYBpAkaZth11kdPcKensny22VPngxvPf9ukNKBHEMpMaAr_NEALw_wcB

Ace Hardware has this gear puller for $7.99.

You could warm the brass gear with a soldering iron, but I find a miniature blowtorch useful for all sorts of things besides freeing stuck gears!

#15

Open flame in my workshop is a health hazard.BTW, I forgot my Bachmann password, as I very seldom use it. After two days, I still haven’t gotten an email from them about getting a new password. Tomorrow I will call them, and Ozark Minatures (but that’s a whole 'nuther problem)!

#16

Well, here’s the evidence that the reworked motor actually works.

#17

Thanks Pete!! This gives new hope for my trolleys…

#18

USA Train motor block is $49.95 at Charles RO and I have used these many times in the trolley. Wheel base is a little bit longer but that does not bother me nor the people I helped. To date never had to fix the USA blocks I installed.

#19

Dan Pierce said:

USA Train motor block is $49.95 at Charles RO and I have used these many times in the trolley. Wheel base is a little bit longer but that does not bother me nor the people I helped. To date never had to fix the USA blocks I installed.

…

Dan P. You have the right idea…

I did a Aritical on ( http://www.largescalecentral.com/forums/topic/25690/sf-amp-bhc-r-r-bachmann-trolley-upgrade ) here years ago and changed out two.trolleys and now will last a long time. Bachmann first came out with p/u. slider on there motor blocks. Later on Bachmann motor block had none. So ya… Wilt a little modification, the USA fits the bill for us Now slower speeds with lots of power for any hill and the extra electrical track pickup.

Here is short video like your Dan… Mine now run lot slower and more real after these test.

https://www.youtube.com/watch?v=eNXqjcd2gJo

#20

Thanks Noel. I will order one even if I don’t need it at the moment. If no one has one i once used one once from Northwest Short Lines but they would probably be a lot higher in price.