Surging control


hacketet <hacketet@...>
 

Not quite prototype, but still a problem with models of this vintage.

A few of my locomotives suffer from severe surging when running down grade. I just had two derailments on a 2% down grade and 48" radius curve (HO) when the train piled up against the locomotives and the first few cars in the train were shoved off the track.

These were Stewart units that are otherwise very good running units. I know the answer is to put bushings in the drive mechanism to take up the slack. Does anyone know of a web site or other information source that discusses the details of this surgery?

Earl Hackett
Modeling the C&O in 1952


Tim O'Connor
 

Earl

I suggest this wonderful Yahoo group: repowerandregear

Tim O'Connor

Not quite prototype, but still a problem with models of this vintage.

A few of my locomotives suffer from severe surging when running down grade. I just had two derailments on a 2% down grade and 48" radius curve (HO) when the train piled up against the locomotives and the first few cars in the train were shoved off the track.

These were Stewart units that are otherwise very good running units. I know the answer is to put bushings in the drive mechanism to take up the slack. Does anyone know of a web site or other information source that discusses the details of this surgery?

Earl Hackett
Modeling the C&O in 1952


Schuyler Larrabee
 

Obviously, those "first few cars in the train" were ALL steam-era freight
cars . . .



The usual fix is to place washers on either end of the worm gear in the
trucks so as to reduce to a minimum the forward and backward motion of the
worm gear. Not so much as to introduce any bind in the worm gear's
rotation, but so that it will only slide back and forth a few thousandths.
The surging comes about from the wheels trying to push the gears faster than
the motor is running them, so they push the worm gear to one extreme end,
and they momentarily bind up, the locomotive bucks, this reduces the
binding, and the cycle repeats.



I second Tim's endorsement of the Repower and Regear list, but I don't think
you need to go there for as straightforward a problem as this.



Schuyler



From: STMFC@... [mailto:STMFC@...] On Behalf Of
hacketet
Sent: Sunday, December 04, 2011 9:18 PM
To: STMFC@...
Subject: [STMFC] Surging control





Not quite prototype, but still a problem with models of this vintage.

A few of my locomotives suffer from severe surging when running down grade.
I just had two derailments on a 2% down grade and 48" radius curve (HO) when
the train piled up against the locomotives and the first few cars in the
train were shoved off the track.

These were Stewart units that are otherwise very good running units. I know
the answer is to put bushings in the drive mechanism to take up the slack.
Does anyone know of a web site or other information source that discusses
the details of this surgery?

Earl Hackett
Modeling the C&O in 1952








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Tim O'Connor
 

Schuyler wrote

The usual fix is to place washers on either end of the worm gear in the
trucks so as to reduce to a minimum the forward and backward motion of the
worm gear. Not so much as to introduce any bind in the worm gear's
rotation, but so that it will only slide back and forth a few thousandths.
The surging comes about from the wheels trying to push the gears faster than
the motor is running them, so they push the worm gear to one extreme end,
and they momentarily bind up, the locomotive bucks, this reduces the
binding, and the cycle repeats.

I agree but a more basic question is, are these Kato Stewarts or the more
recent home-made drives? I have a lot of Stewart F units, and I've never
seen them bind up on a downgrade. But maybe my freight cars are not as
free rolling as Earl's must be...

Tim O'


Earl Hackett <hacketet@...>
 

********** Original Message ************

But maybe my freight cars are not as
free rolling as Earl's must be...

*************

The my cars seem to be VERY free rolling. My main yard is perfectly level
according to all 3 of my the carpenter levels - but the darn things roll
down toward the switch ladder anyway. It's a real nusance. I could fix
this by planting some long grass in the yard, but most yards are pretty free
of weeds. I'm thinking about putting some brakes on these cars by wrapping
a resistor around the axles to add some friction and get block detection at
the same time.

Earl Hackett
Modeling the C&O in 1952