Steam & Excursion > Controlling Slipping

Can one of you experts answer a question, dumb or not? .Jack, Wes, or any of you other experts on here?  Conventional wisdom in controlling wheel slip on a steam engine is to reduce the throttle and come back on the steam when the slip is under control.  My question is this:  Instead of easing off on the throttle, hook up the reverser a bit to shorten the valve stroke.  Would this work, or if not, why not?

Brian Black
Castle Rock, CO

tehachcond Wrote:
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> Can one of you experts answer a question, dumb or
> not? .Jack, Wes, or any of you other experts on
> here?  Conventional wisdom in controlling wheel
> slip on a steam engine is to reduce the throttle
> and come back on the steam when the slip is under
> control.


First, to be correct, one does NOT "reduce the throttle". The throttle MUST be shut off completely, until the drivers stop spinning/slipping.

  My question is this:  Instead of
> easing off on the throttle, hook up the reverser a
> bit to shorten the valve stroke.  Would this
> work,

Not only no but HELL NO! Hooking up the reverser would make the drivers spin/slip faster, just like accelerating a train. 

or if not, why not?

All steam MUST be shut off to the valves/cylinders until the drivers stop spinning/slipping, at which point traction adhesion is reestablished with the rails. Even the slightest amount of steam being supplied to the valves/cylinders will keep the drivers spinning/slipping. By the way, never, NEVER apply sand until the drivers have COMPLETELY stopped slipping/spinning!


> Brian Black
> Castle Rock, CO



Edited 1 time(s). Last edit at 03/11/25 13:38 by HotWater.

What Jack said. Especially about no sand. That may work on a diesel, but steam locomotive driver tires are shrink fit to the driver center and in the event sand was applied and traction suddenly regained from sanding, you could slip a tire and that's something you don't want to do. Could do some serious damage.
I did have a couple of instances where the exhaust sounded a little dicey when she thought she may like to slip and reduced the throttle to stop it.  If I remember, it was going over a crossing at a junction in Texas. Was even captured on a Pentrex tape.
I've seen a delayed response to the slipping when someone else was running and one time it was a race in the cab to shut the throttle. High speed slips can be a disaster.  There was a video of a British locomotive breaking loose in a slip and it didn't get stopped and the valve gear flew apart.  Horrible mess.  Wish I could remember the engine name or number.

Don, look on that tube channel for “Blue Peter slip”. It’s the stuff nightmares are made of if you know what’s really happening. Broke both the engineer’s arms when he tried to unlatch the reverse wheel to center the valve gear. Throttle was stuck open and couldn’t be closed, and engine was priming. Bad news.

Scott Gordon

Posted from iPhone

I found the video .... whoa ..... very scary.

Photo of some of the damage to "Blue Peter" Peppercorn Class A2 # 60532 at Durham UK on January 10, 1994.

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Wonder where it is today?  I wonder if the dry pipe came apart?  Nothing seemed to stop the steam. Nasty event!

Additional information:

On SP 4449, Doyle always cautioned me that just prior to her slipping, there is a very slight "shudder". He was right. 

On NKP 765, I never experienced any "advanced warning" prior to he slipping.

Frisco1522 Wrote:
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> Wonder where it is today?  I wonder if the dry
> pipe came apart?  Nothing seemed to stop the
> steam. Nasty event!

Alive n kicking!

https://en.wikipedia.org/wiki/LNER_Peppercorn_Class_A2_60532_Blue_Peter



Edited 1 time(s). Last edit at 03/11/25 16:24 by exhaustED.

Frisco1522 Wrote:
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> Wonder where it is today?  I wonder if the dry
> pipe came apart?  Nothing seemed to stop the
> steam. Nasty event!

From what I understand, British locomotives have a throttle that is something like a slide valve. The crew that day was unfamiliar with the engine. When they stopped at a station on a grade to pick up passengers, they overfilled the boiler with water. When they got started, the engine slipped, it started picking up water, and the engineer was unable to close the throttle. The engine has since been repaired and I believe it has run recently.

Posted from iPhone

Thanks all for the good, information. My hands-on experience on steam is firing a small narrow gauge engine. I knew using sand or the independent brake was a big time no-no.

Brian

Posted from iPhone

Also on YouTube is a late October 2023 cab-ride in Reading & Northern 2102 with a lengthy wheel slipping segment. It's on a curve, on a grade from Jim Thorpe Jct to Nesquehonning PA.  Engineer Shane Fredrickson does everything outlined here by others.  But its a bit scary to watch. Search "2102" on YouTube.

rkennedy2 Wrote:
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> Also on YouTube is a late October 2023 cab-ride in
> Reading & Northern 2102 with a lengthy wheel
> slipping segment. It's on a curve, on a grade from
> Jim Thorpe Jct to Nesquehonning PA.  Engineer
> Shane Fredrickson does everything outlined here by
> others.  But its a bit scary to watch. Search
> "2102" on YouTube.

This may be the video you were referencing…..

https://youtu.be/_VGe7LYqiiE?si=rOwcqpq0BqSOvukd

Shane’s rapid-fire opening and closing of the throttle is interesting, this may have been the first time I had seen this done on video. Notice at times he seems to match the rhythm of the exhaust with his open and close speed. Notice the hand shakes he made…..assume Shane may have arms like a gorilla. My one and only experience with a front end throttle was the 611 in-cab event at the SRR. I was surprised at the effort it took to pull the throttle. The 02 has a bit less boiler pressure than the 611 but certainly the pressure was right to the peg on the 02. This is brutal!

Perhaps hooking up would add more restriction in the path from the throttle to the pistons, in the case of the video it’s like Shane is creating pulses of steam to the pistons, hooking up would slow down the throttle response?

Interesting discussion here.

Randy

Posted from iPhone

Hooking up would make it worse. You have to control it with the throttle. You hook the engine up when you want to gain speed and the "time is right" after moving from a dead stop. Your butt and ears tell you when to hook up.
I understand the engineer on the Blue Peter broke his arm trying to adjust the valve gear, hopefully setting it on center and open the cylinder cocks.
I would expect an engine going into a wild high speed slip uncontrollably had a problem with a broken or another dry pipe situation since you couldn't control the steam.

So, stop it with the reverser. Yes, it shuts off steam to the cylinders BUT it also allows the still open throttle
to bring up the supply pressure to the valves to full boiler pressure and when you notch up the reverser it
hits at full BP making the slip inevitable. Throttle, allow your supply pressure to build up.

Out 



Edited 1 time(s). Last edit at 03/12/25 19:09 by callum_out.

When wheel slip occurs,
The steel rail and steel wheel
are riding on liquid steel….
Mostly seen as sparks around the
rim and rail —— some rails were
quickly worn down, while slipping.

Wheels and rail are both liquified,
because of immense weight.

It takes very little Steam to sustain the spins.

Closing the throttle simply traps
boiler pressure Steam between
closed throttle and valve chest.

Spinning Drivers can go several revolutions, simply on expansion,
even after throttle is closed.

A skilled engineer CAN control Steam
flow.

Greatest advancement in throttles
was the adoption of multiple-poppet
Steam valves in ‘front-end’ throttles .

Throttle valves are effectively an
all-or-nothing device. Open or closed.

Front-end throttle valves are like 5”
in diameter, and my have 5 to 7
separate cams to lift each valve
as controlled by the engineer.

A series of smalller valves give engineer much more control over steam flow/rates.
Better control over wheel slips.


W.

Posted from iPhone



Edited 1 time(s). Last edit at 03/13/25 20:28 by wcamp1472.

I wonder if hogheads ever used a little jamb [Independent brake valve] to stop the slipping?  I have seen this done on diesels. 

Cabhop Wrote:
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> I wonder if hogheads ever used a little jamb to
> stop the slipping?  I have seen this done on
> diesels. 

Diesels yes, because diesel wheels do not have heat-shrunk tires as on steam locomotives.

HotWater Wrote:
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> Cabhop Wrote:
> --------------------------------------------------
> -----
> > I wonder if hogheads ever used a little jamb to
> > stop the slipping?  I have seen this done on
> > diesels. 
>
> Diesels yes, because diesel wheels do not have
> heat-shrunk tires as on steam locomotives.

Not only slipping a tire, but snapping a crankpin or two might be a result as well.