Hi all,
I’ve assembled and installed the gearbox for the brass T-12 locomotive I have been working on. However, upon installation into the locomotive, I’ve found that the gearbox will run smoothly in reverse, but will ‘hesitate’ and bind going forwards. It’s not the driver quartering - this is testing without the other wheels in place. I’ve also made sure that the worm gear isn’t sliding within the gearbox.
The gearbox in question is a NWSL #170-6, 50:1 compound gearbox. Can anyone suggest what might be causing this issue?
Thanks in advance,
tbdanny
tbdany,
I would go back to the basics with the engine first. I have dealt with many cantankerous steamers. More than likely it is somewhere in the valve gear. Take the body of the gearbox off and try to roll the engine forward. If it rolls smoothly 5 out of 5 times then it is the gearbox and could be some flashing on one of the gears but most likely you will find a small glitch in the valve gear. I also try by hand to move the wheels from the driver set that the gear is mounted to. sometimes that will show you where the bind is occurring. Hope this helps!
The problem of going OK in one direction only is often associated with the worm gear!
If the worm gear axle is moving axially (back and forth) it can cause binding in one direction.
I have had it on a few locomotives myself, and I fixed it by making thrust washers/distances between the motor bearing and the worm gear.
You might email Dave at NWSL. He does respond.
http://www.osorail.com/
He has just re-geared and re-motored an old Pittman drive loco for me.
I have used his gears in the past and they are high quality gears.
I have used his thrust washers to eliminate back and forth motor shaft movement.
Rich
I’d be on the side of the “thrust washers” as well, I have experienced this many times with brass locos over that last 40+ years of working on them. It usually doesn’t take much but there have been a couple of times where I actually had to “reverse” the worm gear in the housing, probably due to the worm gear being drilled slightly off center.
They can be “fickle” critters sometimes but stay with it, that NWSL gearbox assembly is “the” thing.
Mark
WGAS
I disagree.
I don’t think the problem is with the worm gear at all. I think it is with the worm. However, thrust washers are in order for it, but on the worm and not necessarily the worm gear.
But if the worm gear is moving from one side to the other, you may need washers on the sides of it as well as its side to side movement may also cause the side rods to bind.
It may be that the entire gearbox changes position slightly. When moving in reverse the reaction force pushes the upper portion of the gearbox forward and the opposite happens when you switch to forward. This may cause binding in the motor coupling in one direction, but not the other.