Slack action Was RE: [SergentEng] Where to purchase

John Hagen


You are absolutely correct about how the prototype deals with slack action nowadays.

That said, I’d venture a guess you weren’t around when steam powered freights were still plying the mainlines.

With the advent of diesel power railroads discovered that heavy freights could be started from stop by stretching out all the slack and using the low speed power of the diesel electric system to get the train rolling.

Steam locomotives did not have such an advantage so, when trying to get a heavy train moving, the standard practice was to back against the train to get the maximum slack built up, open the sanders, and then start the loco as fast as possible. The idea was to build up enough momentum as the slack ran out that the loco, now on well sanded rails, could keep from stalling an impressive flurry of spinning drivers, valve motion and side rods along with a lots of noise, smoke and ciders.

Yes, it was hard on draw bars and was to avoided unless necessary but it could be great to watch, from either end. Of course the best view was to the locomotive end but if you were at the caboose end, often a half mile or so away, seeing the way the caboose would be “snapped” into action was also interesting but more frightening to see than fun. The crew had to have themselves well prepared for the shock they were about to receive. It looked brutal.

It did not totally end with diesels but, as engineers became more attuned to how different they were than steam for starting a train, it occurred less and less as time went on. It can still happen but with today’s motive power it is quite rare. Not to mention that watching the same action with diesel power is just not the same.

John Hagen


From: SergentEng@... [mailto:SergentEng@...]
Sent: Tuesday, September 19, 2017 11:30 PM
To: SergentEng@...
Subject: Re: [SergentEng] Where to purchase




The real RR cars have all kinds of slack action that has to be taken into account of in train handling or there are problems w/ broken knuckles & drawbars, etc. When the real trains leave from a dead stop they have to do it slowly to avoid break in twos. Of course most of us modelers don't run trains over 30 cars so slack doesn't present the same kinds of prototype problems as the real RRs have. Our biggest break in two problems come from bad track work which causes misaligned couplers. >}

Andy Jackson
Santa Fe Springs CA




Posted by: Andy Jackson <lajrmdlr@...>

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