Steam engine runs in reverse but binds forward


7

747flier

Well-Known Member
I have a couple of the delightful Blackstone HON3 K27's and a United Mudhen I re canned, but my original Roundhouse 2-4-0 runs smoothly in reverse but binds running forward. Any thoughts. This is currently a project loco and I have added a number of home made 3D printed parts, including a new tender for maybe DCC and sound.
 
i would first check on the quartering on the drivers .. from your description it will be fairly high on the list ...then check the front of the run bars where they enter the steam chest ...
 
If it's running in reverse but not forwards, it isn't the quartering, if it was, it would bind within one or two full rotation of the wheels in both directions. I also suspect its not the piston rod or steam cylinder, for the same reason.

Check your connecting rods and see if any of them have a lot of play in them, also did you have this problem before you added your custom 3D parts, or didn't you run it at all prior to now?
 
I would take the motor completely out (i'm assuming it has worm gear?). Then run it by pushing and/or applying some pressure on top of the main frame with a finger, at the same time watching how the valve gear works. Especially important if there is a full reversing mechanism on it, because it faces one way on the steamer (usually), one of the links might be binding one way, but not the other. You might even feel the moment of bind with your finger.
 
Thank you gentlemen! It ran pretty well till I decided to re motor it. These old MDC Roundhouse steamers have pretty primitive rods and gear! So taking it apart wasn't the desired trick! The United K27 I re motored came out well! I'll DCC it when I get tracks up and running.

Cheers: Tom
 
KriegslokBR52 said:
I would take the motor completely out (i'm assuming it has worm gear?). Then run it by pushing and/or applying some pressure on top of the main frame with a finger, at the same time watching how the valve gear works. Especially important if there is a full reversing mechanism on it, because it faces one way on the steamer (usually), one of the links might be binding one way, but not the other. You might even feel the moment of bind with your finger.
Click to expand...
This is similar to what I was going to say. Valve gear, or a motor thrust issue where the slop in the worm on the gear is different going the one way over the other.
 
By making and adding thin washers to the shaft of the connecting rod driven by the gear train it does now generally run without severe binding, though still much better in reverse than forward. The worm is directly on the shaft of the motor and I think the worm engagement changes with fore or aft torque. Putting a mini clamp on the back of the motor to change the engagement angle minutely may have helped?

It's been alleged that certain nationalities had more reverse gears than forward in their tanks, to enhance retrograde maneuverability.
 
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