sidetrack
Foreman
Joined: 02 Apr 2006
Posts: 30
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| Improved KMT Drive |
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For many years I never bothered with older brass locos until I decided to do the Santa Fe GP50 PH II . One of the reasons was the poor or no performance of the gear drives or lack there of.
However, after doing the GP50 project, I decided to take a closer look at the mechanism and thus the research began.
The motor in the unit is a Canon CN22 to which I added a pair of OMI flywheels and shortened the the length of the shaft and changed the coupling.
The next problem I encountered was the gearing on the trucks and the drive shaft in the gearbox itself. I looked what NWSL had to offer and it wasn't what I wanted. After doing more digging I came across Hobbytown of Boston, under Bear Locomotive.com.
This is a REAL conversion and I will say that the modeler who is willing and has the tools can make this imrovement to ANY 4 wheel KMT drive and possibly the 6 wheel version.
This conversion is for TOWER DRIVE 4 AXEL DIESEL LOCOMOTIVES
Items needed from Bear Locomotive for 1 truck:
2 Helical Gears
12 #2017 flat steel washers
2 #4297N wheel sets no bearings Nickel plate
Items needed from NWSL
The Puller or The Puller II
Professional Press tool set #4539-4
Other Items
vice or press
tweezers
mini pliars
mini files
small saw
brass tubing, hollow, 7/64th to fit around Bear locomotive wheel axel as sleeve and making sure it fits in the wheel well , not tightly.
1 diesel locomotive wth the KMT drive
Alot of Patience 
Step 1
Remove one of the truck from the locomotive and inspect to make sure that the gearbox and tower have no cracks. Remove bottom cover plate. Remove the sideframes and set aside. Inspect the 2 gears on the tower and the one on the drive shaft. If they are cracked or worn, replace with NWSL gears. Remove the trucks. Remove the bronze bushings and washer and set aside as we will reuse them. With the gear puller, carefully remove the 2 worm gears on the shaft. If the delrin tooth gear is worn or cracked , replace. Please note that the helical gear is shorter than the steel worm. Next, take one of the helical gears and slip over the shaft . Then take the two bronze bushing , that we set aside and press the helical gear on but not too far.There is a knwarl on the shaft .DO NOT go past that. Remove the bronze bushings and do the same to the other side. You will then need to put a bronze bushing on each end and set the shaft in the bottom of the gearbox. You will need to make sure that the helical gear is centered where the wheel well is. If you have it centerd, then remove the bearing and slip on 6 steel washers on each end followed by the bronze bearing. Reinstall the gear tower , makiing sure they are straight and the gears should turn by hand very easly. You can screw the bottom back on if you want but it is not necessay at this point.
Step 2
Get the 2 Bear Locomotive wheel sets. You will notice that one side is insulated and both sides have brass washers.
Get the brass tubing.
We are not going to use the brass washer on the insulated side. Remove that side and measure the distance from the end of the helical gear to where the wheel wil be pressed back on. Don't make your piece tool tight. Make sure you have a clean cut and remove any burrs. Make sure the sleeeve is not out of round! Install on and see if it turns freely on the shaft. Next, press the insulated wheel back on. remove the other side. Measure the distance but , we want to use the bronze flat washer and make this sleeve snug. This is bit of a hassle but necessary, not unless I find a better solution.
Step 3
Before installing the wheels into the bottom box, make sure the wells are clear of any debris. You might want to put a drop of oil or lube in the well. Next, install the wheels. If the wheels are too tight carefully pull apart but be sure that the side that the washer is in is centered.
Next , with the gearbox upside down, turn the gears on the tower. Make sure that the helical gears are in place. They might be a bit loose but that is ok. Remove the wheels, install the side frame , reinstall the wheels and put bottom cover on carefully. DO NOT overtighten. You might have to make adjustment with the bottom cover plat but I assure you, you will have enough clearance. If everything is ok, you should be able to roll the truck on a track or piece of paper and the tower gear will turn freely! Reinstall on locomotive.
Step 4
Start again at step 1 and do the other truck. 
Step 5
Run locomotive
All parts were ordered directly from Bear Locomotive.
I will see about getting some photos posted. |
Sat Jul 01, 2006 11:03 pm |
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ShopMaster
Site Admin
Joined: 18 Mar 2006
Posts: 227
Location: Royal Oak, MI |
Carl explains his photos:
"Starting from the left side in the photo, we see 2 of
the washer that I used about 6 on each end of the
drive shaft. Below them are the new helical gears.
Next we see the the original KMT drive and to the
right is the original shaft and bronze bearing but
with the helical gears and washers installed. To the
right we have 3 wheels. All 3 are the replacements
from Hobbytown. The top one shows in original form.
Below , you can see that I removed one of the brass
washers and installed a brass sleeve. Below is the
finished wheel with 2 brass sleeves and one brass
washer on the uninsulated side. To the right is a
piece of a brass sleeve."
"In this photo we see the drive shaft and one wheel
installed in the original KMT truck. No fililng is
needed as the wells and bottom covers allow for the
gears to turn freely."
Last edited by ShopMaster on Sun Jul 16, 2006 5:37 pm; edited 1 time in total |
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Fri Jul 07, 2006 8:09 pm |
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Brasscrafter
Brakeman
Joined: 12 May 2006
Posts: 24
Location: Toronto, Canada |
This looks like a much better alternative to trying to rebuild an Atlas or Athern truck to fit, as I was doing. I'll definately be taking a look at Bear Loco for the parts that I need. Thank you for the tutorial. I know that it must be a ton better, but how would the drive rank on the smoothness scale? Does a Bear rebuild give you a $5 Bachman, or a top line Kato? |
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Wed Jul 12, 2006 1:50 pm |
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sidetrack
Foreman
Joined: 02 Apr 2006
Posts: 30
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"I know that it must be a ton better, but how would the drive rank on the smoothness scale? Does a Bear rebuild give you a $5 Bachman, or a top line Kato?"
How about TYCO!!!! 
I haven't had a Bachmann in years and never owned any Katos. I mainly have OMI's , some that I have rebuilt.
Actually the unit is very, very smooth and quiet, but since I did the article I have some changes to be made.
First, I will be changing the gears in the towers so the unit will go at a more realistic slower speed. I alread know what gears to set up for and hopefully I will be able to get them.
In my article I mentioned that the unit was a Canon CN22 it should be EN22 that I added OMI flywheels to. These are nice motors and well worth keeping.
Also, about placing the gear drive in the box. I had to make an adjustment on the gear towards the tank. I had to remove 2 washers and pull the gear a little more out. This is going to vary from box to box as you don't want the gear shaft to be sloppy or the wheel gears interfering with the washer spacers. Another problem I encountered was, one of the gearbox covers had some metal that was interfering with the wheel gear. I carefully filed it down.
I'm sure that more improvements will be made by me , you or someone else. I will let you know , that , before I did this , I had purchased a set of GP powered trucks complete from Bear Locomotive. I could get the trucks to fit the frame but the towers are to low and I couldnot get the Hallmark sideframes to adapt. This will save someone some $$ and time. |
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Thu Jul 13, 2006 10:32 pm |
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Brasscrafter
Brakeman
Joined: 12 May 2006
Posts: 24
Location: Toronto, Canada |
I will make sure that I have your notes available when I do the next rebuild. I have some Alco Models electrics that I hadn't decided what to do with them, all needing complete rebuilds (With KMT drives, of course.) I know exactly what you mean about adapting the sideframes to a new truck - I had a lot of fun building a set of truck cradles that the brass sideframes attached to that sat on top of an Athearn power truck. It worked, but I don't think I would do it that way again. I was going to build a whole knew truck casing, figuring that it would run smoother, but again, a ton of work. I'll try out one of the Bear Loco kits first. Thanks again. I have a question: Do you think that having the KMT drive casing re-worked and then cast in brass a worthwhile part in the rebuild? I was thinking that part of the slack and the premature gear wear is coming from a worn case. I bought one unit that had almost .060" slack in the drive tower. Needless to say, it didn't run very well. Mark |
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Fri Jul 14, 2006 12:29 pm |
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sidetrack
Foreman
Joined: 02 Apr 2006
Posts: 30
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"I have a question: Do you think that having the KMT drive casing re-worked and then cast in brass a worthwhile part in the rebuild? I was thinking that part of the slack and the premature gear wear is coming from a worn case. I bought one unit that had almost .060" slack in the drive tower. Needless to say, it didn't run very well. Mark"
That all depends on the time , tools and how much you want to spend. Are we talking about a 4 or 6 wheel gear boxes? Is the slop in the towers only or is it in the gears in the gearbox? I believe in most of the towers are sleeve bearings that the 2mm or larger shaft rides on. If this is worn or missing that can be the culprit. Perhaps the previous owner changed out the towers and it could be the wrong one.
Sometimes you can find an OMI drive , on Ebay, that would be a good replacement. |
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Sat Jul 15, 2006 9:36 pm |
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Brasscrafter
Brakeman
Joined: 12 May 2006
Posts: 24
Location: Toronto, Canada |
I agree that a replacement would be a faster route. It would be a bit painstaking to do, but with all of the old KMT drives out there, it would almost be worth doing. I was talking primarily about a three axle truck, but I also have two and four axle trucks to rebuild. |
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Mon Jul 17, 2006 6:56 pm |
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sidetrack
Foreman
Joined: 02 Apr 2006
Posts: 30
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I"m sure some of you have wondered what ever became of the project and in all fairness I will explain.
The parts I had acquired were enough to do several units and since the article was done, I have actually made more modifications to the drive. One being that instead of using the Bear Locomotive wheels in the KMT drive , I removed the gears from the KMT wheels and reamed out the Bear helical gears to fit the KMT wheels.
The other is, I re geared the the towers with some NWSL gears. Different towers use different gearing.
Due to the fact that the parts needed are not longer available from Bear Locomotive , it has caused some delays. Howard Mosley of Bear Locomotive has posted his letter on another site. 
However, I am in the process of trying to get the gears and several other parts .
I soon hope to have a finished model .
Carl |
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Fri Mar 16, 2007 9:47 pm |
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sidetrack
Foreman
Joined: 02 Apr 2006
Posts: 30
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Here is a photo update on the KMT drive 2 versions are shown.
One, with silver paint is the Hallmark original sideframes with new gearing
The other is a Pacific Pike with new gearing and OMI sprung Bloomberg sideframes. The Pacific Pike wheels have blunt ends, allowing the OMI sideframes to have a nice fit.
Gearing , minus the towers is shown as well. I made several templates of
towers and new castings are in the making.
More to come!!!
Carl
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Carl |
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Fri May 04, 2007 4:56 pm |
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archebald23
Joined: 09 Dec 2009
Posts: 1
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What happened to this project? This would have been a very informative topic.
And good choice with the
driveshaft
, it has better traction, smooth, and minimal maintenance. Im on a similar project and it would have been helpful if you continued the post. |
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Wed Dec 09, 2009 1:34 am |
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sidetrack
Foreman
Joined: 02 Apr 2006
Posts: 30
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The project was going fine until one of the suppliers went out of business and the other sold. I was informed that parts were "not available"
However, I have had one mfg who has shown an interest in possibly tooling new gear boxes and towers. Being able to adapt the original sideframes or retro fitting ones from PSC, OMI , Athearn, Atlas or Kato.
We will see what happens in the weeks ahead!!!!!!!!!
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Carl |
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Tue Dec 29, 2009 10:43 pm |
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MikeOz
Joined: 12 Aug 2010
Posts: 1
Location: Bettendorf. IA |
Hi Sidetrack,
Any luck with the replacement KMT tower drive mechanism? I know it has been awhile.
MikeOz |
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Thu Aug 12, 2010 1:13 pm |
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sidetrack
Foreman
Joined: 02 Apr 2006
Posts: 30
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quote:
Originally posted by MikeOz
Hi Sidetrack,
Any luck with the replacement KMT tower drive mechanism? I know it has been awhile.
MikeOz
Hi Mike,
Welcome to the Forum!
I have not hear anything from anyone , however that doesn't mean that there is no interests. It's evident that many companies have and are scalling back on certain production due to the current economic situation.
Carl
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Carl |
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Sat Aug 21, 2010 10:54 am |
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