Intermountain ES44AC drive shaft issues - no power going to rear truck

[LOCO_GUY]

Hi Guys,

I am hoping someone here knows or has heard about issues with the Intermountain ES44AC drive shafts. My train started slipping so I took it off the layout for investigation. After removing the body top and putting on the test track I could see the motor turning but only the front trucks were powered. I disassembled the rear drive shaft but eveything looked good. So I put the drive shaft back and tested again - only to find that the part of the drive shaft that goes into the brass flywheel was not spinning correctly and not passing power to the truck.

I did the same with the front drive shaft and it looks identical to the rear one. So my conclusion was that there must be some plastic sleeve or mechanism in the brass flywheel that has worn out or broken.

Does anyone know of a fix for this or is it time to send it for repair? 

[modelmaker51]

I would say send it in for repair.

[mlehman]

Most flywheels are drilled and slotted to accept the end of the driveshaft. That's usually the part with the least propensity to wear out. There could be an insert, but more often is not. If it has double flywheels, what do you see at the other end where the driveshaft comes in?

How are the driveshafts made? One piece plastic casting? Brass shaft with slip on yokes? Or?

[gmpullman]

Hi, Locoguy

I had just encountered the very same problem with a pair of BLI Alco RSD-15s that I have had for at least ten, maybe twelve years. I noticed that they were not pulling well and that I could hear the motor spinning but no movement to the wheels.

I diagnosed the same problem that you are having. BLI's driveshaft (some call it a dogbone) has a hex/ball at one end and a ball with two projecting pins at the other.

The hex/ball goes into a broached hex recess in the flywheel.

I measured across the flats of the hex end and I don't exactly recall but it seems like I got .185" or so — but they were loose enough that you could spin them inside the hex recess in the flywheel.

I emailed BLI and they sent me four replacements and I measured the new ones and they were only about .001 larger than the originals! I installed them and the engines are running fine now. BLI hinted that I was suddenly reversing the locomotives or stopping too quickly. Of course this is not the case. I asked them about a newer RSD-15 that I recently bought and they assured me that the drive shafts on that one would never give me any problems... Maybe they had used a softer nylon on the early ones?

I would contact Intermountain. They will probably send you new shafts for little or no cost.

Good Luck, Ed

[LOCO_GUY]

Thanks for the replies everyone.

Ed, you nailed it - that's exactly what I am getting and the part you describe (dogbone) is what I have. I'll contact Intermountain and let them know the problem.

[LOCO_GUY]

FYI,

Ed, I had a thought about how I could keep this loco on the rails while waiting for the replacement drive shafts. I took some heat shrink - tight fit - and put it over the hex end that goes into the brass flywheel. I trimmed the heat shrink and applied some heat and then slipped it back into the brass flywheel.

Hey presto - it worked - so I can keep it running while I wait for the replacements.

[mlehman]

Brilliant idea!

[gmpullman]

mlehman

 Brilliant idea!

 

I second the nomination!

My temporary cure was to carefully wrap Teflon tape, the kind plumbers use, around the hex-ball until I had some thickness built up. Then I trimmed off the excess and pushed it into the flywheel.

 

Who knows? These "fixes" could very well last forever but since a replacement part is available I went that route. It ran fine for a few weeks until I had time to install the new replacement. I’ll keep the old one as a spare.

 

Again, I'm wondering why these wore out in the first place? Perhaps the hex shaped recess is not very smooth inside the flywheel and causes premature wear on the soft plastic drive shaft. In reality, the contact or engagement surface area of that little six-sided ball is very minimal, indeed.

 

We model railroaders are a resourceful lot... gotta be 

 

Good Luck, Ed

[mlehman]

Ed,

I this case, sounds like IM has some issues with the part in the first run. They may have changed the design or mold to fix it since, so are offering the new parts as a replacement. Plastic shrinks in the process of molding, so the change has to be accounted for. If they overdid it the first time, the part may not have been long enough? Just guessing here based on reported symptoms. So the new one is just a little bit longer.

[LOCO_GUY]

Mike, Ed,

Thanks for that feedback :-)

It was pure luck that I came up with the idea. I read what Ed said about the wear on the hex end and just happened to be at my workshop desk with the train and a box of heat shrink staring at me. Suddenly I thought why not try to build up the wear with heat shrink.

Anyhoo, hopefully the idea might help someone else - especially if they can't get repalcement drive shafts.

I must mention here that Intermountain have very good customer service - just called 1-800 number and they took the order for the replacement drive shafts right away. 

[SouthPenn]

Almost all my 'F' units are Stewart/Kato engines, some over 20 years old. They have been run a lot as they are the primary engines on my layout. One thing I have done over the years is put a drop of oil on the u-joints and slip-joints. I also add a couple of drops to the gear boxes. I have never had a failure of any drive line componate in these engines.

Don't put too much in the u-joints or it will spray oil all over the inside of the engine.

South Penn

[jjdamnit]

Hello All,

Great "Necessity is the mother of..." fix for worn hex connections!!!!

I too had a similar moment. I recently picked up an Athearn BB SW-1500 to upgrade to DCC. 

As I was cleaning and inspecting the running gear I noticed that both the Horned Ball couplers attached to the motor were cracked. The motor is a 5-pole unit worth using. Unfortunately the shaft diameter is 1/8-inch.

I searched many an aftermarket sources to no avail. There was an article in the NMRA magazine about re-motoring. The author fabricated a driveshaft of square brass tubing with plastic tubing couplers to the motor.

As I was tinkering with the brass and plastic tube idea it occurred to me, "Why not just fabricate a collar out of metal tubing and slip it over the cracked parts?" I went to my scraps of metal tubing and found a piece of 1/4-inch brass tube that just barely fit over the ends of the couplers.

I cut two pieces of tube 1/8-inch long, press fit them on to the cracked couplers and then pressed the couplers onto the motor shafts. I've been test running the loco for the past two hours with a 5-car load with no slippage!

The next project is an RS-11 with hex couplings on the flywheels. I'll keep in mind your fix for this project.

Hope this helps.