Truck Problem with (OLD) Roundhouse Shay

[richardstallard]

I bought an early production HO standard gauge 3-truck shay when on holdays in the US in 1984.

I was never able to get it running very well and, as a result, it has spent most of the last 20 years in a drawer.

I recently dug it out and discovered that the axle slots in the truck sideframes appear to be too deep, with the result that the weight of the entire loco is resting on the worm gears, rather than on the axle bearings. The loco rocks side-to-side which confirms that the axles are not contacting their bearings.

The main problem with the running quality has been that the motor always seemed to be working hard to the point where it got quite hot - which would be explained by the increase in friction with the weight being taken on the gears.

The problem is not that the axle slots are worn as it has never done much running and the pressure on the gears would prevent the slots wearing anyway.

Has anyone else noticed this problem?

Some options to fix the problem are to:

1. Fit some sort of packing, e.g. segments of brass tube, at the top of each axle slot to form a bearing surface at the correct height.

2. Assuming the problem has been fixed sometime over the last 20 years, buy some spare truck frames (if they are available) and replace the originals. This also assumes new frames would be otherwise compatible with the originals.

Any suggestions would be appreciated.

Many thanks.

Richard Stallard
Perth, Western Australia

[Anonymous]

These are obviously old problems that all early MDC Shays suffered from, mine included. There have been several articles in the model press over the years offering ways to correct them. There is (or was) a small soft cover book on assembling the Shay which I believe addressed the problems.

My Shay was a two truck one, and from what I recall, these are the suggested solutions: The operating gear train on the side are there just for show, and does not require to be connected to each wheel gears. Remove the small gear on one shaft of each truck so there is only one working. This fixes the out of synch gearing and worked on mine.

The effect of the engine "waddling" down the track can be fixed by adding a small square piece of styrene under the frame near the center point of one truck. This acts as a stop to prevent the side to side movement. Later MDC Shays had this block cast into the frame. If you can find a later one, you will be able to see it.

The motor runs fast because of the gearing, and its the gearing that causes almost all of the noise. I orginally thought the motor was making the noise until I disconnected it - quiet as can be! NWSL offers replacement metal "bull" gear for the Shay, but I don't know if this makes it any quieter. Their replacement parts would have cost me more than the engine did, so I passed. I think newer models also have can motors.

After I did the modifications to my Shay, it ran much better. Then I had the problem of the truck baseplate coming undone. This would allow the gears to drop out of line and the engine would go nowhere. I replaced the baseplate, but the problem persisted.

Another problem I had to fix was the large plastic housing for the main gear hung too low between the rails, often catching on switch points. I just filed some off the bottom to fix it.

After all of this messing around, I picked up a Bachmann 3 truck Shay - what a world of difference (and five times the cost too!). I've since sideline the MDC Shay as being too much trouble to keep on fiddling with. I had an MDC three truck Shay kit, but sold it a long time ago because of the problems I had with the two truck one.

Good luck!

Bob Boudreau

[cacole]

I have two of those old MDC Shay kits, one assembled and one still in the box. They were trashy. I also bought a book on how to rework the Shay with parts from several different manufacturers, including all new gears, trucks, and motor. After reading through it, I realized that it was going to cost more to get the Shay to run than what it had originally cost, it was so horribly designed. I put the one assembled version on a display shelf and bought Bachmann Shays. The MDC pre-assembled Shay runs OK because it was made in China and not by MDC, but the old kits are hopeless.

[richardstallard]

As a quick test, I glued 0.25 x 1 mm styene strips in the top of each axle slot. This has made a world of difference!!! It seemed to be just enough to take the pressure off the gears. You can tell if each truck is OK by turning the worm shaft by hand, and applying light pressure to the wheels to force them against the bearings.

It is still noisy, especially at high speed (for a Shay), but it is much smoother and there is no violent wobbling. Also, the motor doesn't run nearly as hot, indicating it is doing less work.

Pleased with the results so far, I installed a DCC decoder (Lenz 1035 in the rear tank) - max speed of 3 seems about right for a Shay and it keeps the noise down. I am now putting lights in using SMD LEDs.

I plan to run it for a while. If the styrene wears out, I will do the same again but with brass strip. BTW, I used Pliobond glue and wiped the oil from the slots, then brushed with Testors liquid glue to get the last of the oil off before gluing.