Why would a Mantua Mikado....

I think there is alot of tension in the drive train.

I suspect there is alot of "Shove" going on when you try to turn the worm gear one way but not the other. I cannot explain it with words.

If you reversed the entire drive motor, link, worm gear and had it sitting in the smoke box "Pulling" on the drive wheels instead of shoving... I suspect you might have a engine that runs well.

The other thing I could think of is the brushes. If you can replace the motor with a very good can motor with lots of power your engine might run very well. But I think the worm gear's orientation to the rest of the drive train might have someting to do with the extra resistance going forwards.

Thanks, I'll check out the seating of the engine and make sure it's not binding at all. I don't think it is, I was considering that when I reassembled it.

I'll also manually turn the engine in each direction and see if more force is required in one direction.

NYC,

I've got three of the engines. The problem is that there is a lot of end-play (slack) in the armature in the motor housing. If you look closely at the motor when it is running, the brushes track in one area of the commutator when going forward and in a different area when in reverse. You will need to remove the slack so that when running in either direction, the brushes track in the same place, preferably the center. Easy to do!

Take the motor out of the engine and determine which direction the armature needs to be moved to have the brushes centered. Notice the gap between the motor's bearing on the end of the armature and the end of the (usually) commutator. You need to fill this gap. Using either a Kadee 0.010" or 0.015" coupler shim (sometimes you have to use two,usually 0.010"), cut a small V-shaped notch out of the side of the shim with small diagonal pliers. You want the opening to be narrower towards the center of the shim. Holding the shim away from the V-notch you just cut, slip it on the armature shaft in the gap. You want the slack to be taken out, but the armature must still rotate freely. I lubricate the bushings and the new shims with a small drop of Dexron II transmission fluid, then "run in" the motor from a power pack for a few minutes in both directions at varying speeds. When you are satisfied that the motor runs the same in both directions, especially at very slow speeds, re-install it in your engine.

Before installing the motor, clean the commutator (thats the 5 brass flat surfaces on the armature) before testing. Remove the brushes and use a tiny strip of 400 grit or higher sand paper. Poli***he commutator until it is shiny. Don't use a pencil eraser.

Your motor should run very well. It took me quite a while to figure out what was wrong when I originally had this problem. Now, that's the first thing I look for if an engine runs faster in reverse than in forward. Fixes it every time.

Mark C.

Also, check the mechanism for binding. The easiest method I've found to do this is to disconnect the tender (leave the drawbar on the locomotive, and remove the boiler casting and the motor. Sit the frame on the work bench, grasp the drawbar and pull the frame back and forth across the bench top. The wheels should turn smoothly in both directions. If not, here's where your detective work comes in.

If this, nor the motor end play reveals a problem, change the brush springs. One spring will lose it's tension and weaken even more as the engine runs, causing poor contact on the commutator.

Mantua engines can be VASTLY improved by dumping the Pittman motors and replacing them with a can-type motor. The simplest way to add one is by adding one of the Alliance Humper Helix remotoring kits (available through Bowser). Overall performance is improved, and the slow speed control is light years ahead of anything Mantua ever designed. And you won't have to deal with fiddling with the existing drive train to eliminate the gear backlash.

The problem could be the motor. When the motor makes the engine go forward it pushes the armature back. When it's in reverse it pushes the armature forward. The rear bearing and washer of the motor might be getting worn from running forward a lot. You could try putting a thin washer in the back of the motor to seperate the rear washer from the rear bearing and see if that helps.

MOTOR ARMATURE:

before: --[]-l-[:::]{}{}{}{}{}-l-[]
with extra whasher: --[]-l-[:::]{}{}{}{}{}-l-l-[]

(shaft = -)(washer = l)(commutator = [:::])(armature magnets = {}{}{}{}{})(bearings = [])