Grades,stall vs slip and stripped gears

Stripped gears can get to a point that causes a jam, then you’ll get a stall, naturally,……beings you’re punishing this poor engine on a monstrous incline, what’s your maintenance practices look like? That’s what I’d be interested in knowing,…..let’s see your failed components to make a determination, …….but looking at it from a mechanical perspective, you’re asking that engine to climb straight up a wall at 11% ….

Pat

WOW!  The gears and running gear in the Shay are fragile as is, but climbing an 11% grade is probably a bridge too far for any reasonable lifetime.

I think you misread the literature.  After reading the overview at MTH's website, they are talking about the prototype Shay climbing 11% grades.https://mthtrains.com/20-3106-1

"The West Virginia Pulp & Paper Company's Shay Steamer No. 12 was there, trudging up and down grades as steep as 11 percent ..."

That being said they do also indicate this should perform on any grade you can throw at it, but they dont say for how long it'll last!

Any locomotive will do it once ……😉

Pat

For years, modelers have used the concept that a locomotive should start spinning its wheels if its overloaded.   We have only added weight as long as the loco could still slip.    This allowed the mechanism and the motor give a warning that the grade is too steep or the load is too much.

However in today's world, manufacturers have put rubber tires on some of the wheels, so they don't slip the way they used to.   in some cases they don't slip at all, so the motor stalls, and when it does, the amps it draws shoot up and the motor heats up or the electronics overload and burn up.

Now if you add a more powerful motor, maybe it doesn't stall and heat up.    Then maybe if the rubber tire wheels won't slip, and the motor won't stop, the weakest link in the mechanism will give way.    That might be a gear or a universal or some other component.    You are probably dealing with a situation like this.

Small dia pins on the shaft that transmit motor/gear box motion to the driving mechanism for the wheels can shear.  So until you determine which gears are fine, and what mechanism is turning free this may be a simple repair.  But if your gear box and motor worm got chewed up you have a more elaborate repair.  G

@harmonyards posted:

Any locomotive will do it once ……😉

At least part of the way up...

What ^^Jim said.  The combination of motor, loco weight, traction, and gear ratio should result in the wheels spinning when the loco is overloaded, before the motor reaches its rated stall current.  Unfortunately, most 3-rail O gauge models are geared too tall, and rubber tires are a devil's bargain.

Allowing for a little wheelspin in the design can spare gears, motors, drive rods, electronic circuit boards, and who knows what else.  But, no, almost 40 years ago at the dawn of the Scale Revolution, someone decided that if one tire is good four must be better!  So now the Forum is overrun with threads about rubber tires

It doesn't matter that the "real" Shay climbed an 11% grade.  The physics just don't scale down.  The curves on your logging branch might be much sharper than on the prototype, adding friction.  And the ratio of starting/rolling friction to mass is probably a lot higher on our O gauge models when compared to the real thing.  Hopefully you can get parts.  But 24 oz of pull is equivalent 48 free-rolling cars on level track.  You're asking a lot of your loco, and it'll probably fail again unless you can figure out how to ease its burden.

Comparing our o gauge locos to the real thing might not work. I have spent some time operating the real thing on grades and curves. It is all about SAND. That is not an option with your o gauge loco. The use of sand on the rail is all about being able to get where you are going or not.

The other thing about climbing grades on a real railroad is many were grade compensated. Pulling cars around a curve requires more effort than on straight track. When the grade was also curved, the grade was reduced to compensate for the curve resistance. The rule of thumb was each degree of curvature was equal to 0.1 % of grade. So if you were operating on a railroad that had a maximum grade of 1%, a ten degree curve would be reduced to level to maintain the 1% grade pulling effort.

As for stripping gears, on a real Shay the only gears are the ones on the wheels. Those gears wore out quickly and shops were always in there welding the teeth up. They would let the natural wearing of the teeth reprofile them.

I am with Ted on this one. Rubber tires are a terrible thing to do to a motor. The wheels need to slip to limit the load on the motor. The slip is adjusted by adding weight.

Have found the failure point. Any ideas?

@AL THE OPERATOR posted:

Have found the failure point. Any ideas?

Well, they make this part in stock at MTH parts

So I would drill out the bracket to accept the bushings, and then assemble with the new gear- and carefully adjust gear mesh, and keep it lubed.

https://www.mthpartsandsales.com/shop/search/results

Transfer gear mount has elongated

Also, the Lionel version of the shay uses a similar part, but also not available.

https://www.lionelsupport.com/...E-W-MOUNT-2-TRK-SHAY

What is the gear support bracket made from? If it is brass, you might be able to solder a plate on the outside of each supporting arm and then drill for the new bushings. If it is a die cast part, you might be able to use an epoxy adhesive to secure the plates, then drill them.  Perhaps you could even use a metal-bearing epoxy to fill the elongated holes, then drill or ream for the bushings.

If you are able to repair it, then I'd say keep it off that 11% grade!

Thanks for all the input and advise.

I am first going to attempt to beef up the existing bracket and refit the gear on a slightly larger shaft.

What would be the suggested "rated stall current" for the motor or the fry current for the electrical/electronics?

I'm still going for the 11% grade even if I have to redesign the gearing completely.

That is attached to piston assembly correct?  The whole assembly comes off and is/was a replaceable part.  G

I just checked and that gear bracket does come with the piston assembly. One side has a bracket going down to the driving shaft, then the other is screwed on as shown.  It is not a separate part as you would have to fully disassemble the piston assembly cranks, gear and such to get it off.  Those are pressed on fittings.

I do have a broken piston assembly that you can salvage the screwed down bracket and gear by drilling out that rivet.  Then reassemble with a new rivet/pin assuming the bracket on the drive axle is in good shape.  G

Hopefully George (GGG) and other electronics experts on the Forum will tell you what the PS2 circuit board stack is rated for.

If your Shay has a Mabuchi RS-385 motor, I would advise that the current draw of the MOTOR shouldn't exceed 2 amps continuous, or perhaps 3 amps peak.  You could invest in an infrared temperature sensing gun and run it with the shell off to read the temperature of the motor case.  My guess is that you'll shed rubber tires, or some electronic component would fail before the motor does.