The Infamous 1994 "Blue Peter" Wheel Slip Incident On Film

Dave · **Posted:** Thu Jan 03, 2013 7:22 pm

Now I'm getting interested in technical details.....

that "jammed" throttle: I wonder? Most British locomotives I know anything about have throttles that slide a flat blanking plate off a series of 2 sequential slots, not a spool lifting out of a hole as we do. I'm trying to imagine how high water could prevent sliding the plate home....I've never run one like that. Pleased to hear from experienced British engineers about it.

Yes, my practical experience in mountain rialroading is like John's. Throttle, then sand, then try again.

dave

J Kreider · **Joined:** Mon Nov 26, 2012 12:10 am **Posts:** 21

I’m curious about the installation of the superheater units in relation to the throttle on modern British steam. Mention has been made on this post to residual steam in the units contributing to an uncontrolled slip even with a shut throttle. This, of course, would be the case with dome throttles which had the superheater units installed downstream of the throttle.
On modern American locomotives with front end throttles, the superheater units are usually installed upstream of the throttle so that closing the throttle prevents residual steam in the units from playing havoc with a slip. It also enhances the engineer’s ability to make more precision stops because when he closes the throttle, that is essentially the end of the steam supply to the cylinders.
Am I thinking about this right?
Jim Kreider

JohnHillier · **Posted:** Thu Jan 03, 2013 8:30 pm

Yes, American Multiple Throttles are on the other side of the superheaters from the dry pipe, so you have very instant control over steam entering the valves vs. just waiting for it to cycle itself out through the entire volume of the superheaters as with a dome throttle.

Dave · **Posted:** Thu Jan 03, 2013 8:34 pm

Yes. Front End throttles did leave the elements full of steam, which also protected them from burning out as quickly as dry elements would.

There were many conversions made.....I was responsible for a Baldwin 2-8-0 that was built saturated with Stephenson gear, the converted to superheated with outside admission Walschaert gear. The same throttle in the dome both ways. The only way to hook it up was to trip the latch when she was shoving the Johnson bar in the direction you wanted, and stand out of the way.

Piston valves, superheat and outside valve gear sort of came along at roughly the same time, and worked well together. Lubes didn;t do as well back then with the heavy pressurized slide valves in the higher steam temperature as piston valves, and locomotives were growing to the point thast there wasn't room enough for Stephenson in between the frames.

I think this points up the value of a collection as large as St Louis......you can take notice of the technological progression in a wide range of shapes and sizes.

dave

MD Ramsey · **Joined:** Fri Feb 26, 2010 9:52 pm **Posts:** 192

I remember firing for that same guy!

Russ Fischer wrote:

I agree with Frisco1522. If an engine completely breaks loose in a spinning wheel slip, close the throttle and get the engine back on her feet, apply sand, then reopen the throttle and go on. Adjust the cutoff as necessary with the engine working normally. Trying to control a serious wheel slip with the reverse is not a practical idea and may actually increase the slipping at first.

Even if it is caused by a slug of water in the superheaters, which I have experienced several times, you still want to close the throttle first. Then center the reverse to control the power, if necessary. The steam generated in the superheaters will expend itself quickly enough, although this can be a disconcerting experience.

The "Hand on the throttle" pose is not just a cliche. Engineers handling engines working on heavy grades commonly run with their hand resting on the throttle to be ready to close it at the first sign of a slip. If the engine has a true "Johnson Bar" (manual, not power reverse) the last thing you want to do is unlatch the dog when the engine is slipping. The bar can instantly become uncontrollable causing you serious harm.

This reminds me of an engineer I worked with on the D&S years ago. He had a habit of setting the throttle and sitting back relaxing with his arms crossed. If the engine would begin to slip he would just calmly reach up and turn on the sanders and wait for it to catch again. (Not a practice I recommend.) The K-28 class engines we were running rarely completely broke loose all at once, but would usually just start slipping gradually, so this worked well enough, usually.

One day someone greased the rail for us on Hermosa hill, a 2 1/2% grade. The engine went immediately into a complete, uncontrolled, wild screaming frenzy. By the time he closed the throttle and got things settled down again I had bailed off the seat and was standing in the middle of the cab in case a side rod came through the floor.

whodom · **Posted:** Thu Jan 03, 2013 8:54 pm

American-style multiple valve throttles had the valves downstream of the superheaters (at least all of them I've ever read about) which has several advantages as mentioned above, plus the ability to supply superheated steam to accessories like the blower and air compressors.

Blue Peter had a multiple valve throttle fitted in 1949 according to the Wikipedia article. I believe UK front-end throttles typically had the valves upstream of the superheaters, although I've never understood why. Wardale makes reference to the throttle on SAR #3450 being of this configuration, and I'll bet Blue Peter was the same way.

Overmod · **Joined:** Thu May 24, 2012 1:37 pm **Posts:** 2492

Thank you, Hugh, for establishing some of the details meaningfully. at last.

As I heard the story, priming resulted in severe carryover into the superheater elements -- as noted, ahead of the throttle. This resulted in the slip developing fairly rapidly.

Blue Peter does NOT have a 'screw reverse' like the old power-reverse design with the wheel, as on NYC J1 Hudsons, where the screw controls valves on a power reverse. On these British Pacifics, the screw physically moves the valve gear, and perhaps unsurprisingly, with the increase in inertial force in the developing slip, there was considerable force back through the shaft to the crank... which clocked the driver a pretty good shot, I heard to the jaw, putting him in shock and making him understandably somewhat slow to react. Trying to grab the wheel while it was unwinding would not have helped the bones in his hands and arms, either.

I do not believe there was any actual leakage past the throttle as proximate cause of the continued slip.

This thread relates somewhat to the FRA 'expert' discussions on whether a modern American locomotive superheater can constitute a separately-fired pressure vessel. On modern locomotives with front-end throttles, they can't -- the dry pipe and superheater communicate with each other under all conditions, and there is no physical way you can experience a pressure excursion due to priming or carryover into the elements no matter how the throttle (or valve gear) is manipulated. To the point here: an American locomotive would not have suffered this kind of incident because closing the (multiple) throttle would promptly, within a couple of revolutions, exhaust the steam in the lines between throttle and valve chest, and those lines expose very little surface area to meaningful convection-section heating. (You can't get backlash from a hydraulic power reverse, either, but that's another cautionary tale for the Brits altogether... ;-}

Kevin Gilliam · **Joined:** Thu Nov 04, 2004 10:28 pm **Posts:** 292

p51 wrote:

Thanks for posting that video and photos, I'd heard of it but never saw any of this stuff before.
I had a train fan video years ago of 2716, watch this around 3:07 to see a really long wheel slip: http://www.youtube.com/watch?v=_Ia2Ok9Phaw
I've often wondered why they let it go that long, and what the story was?

short answer....really bad coal and a steep hill and working full throttle on a heavy train at about 2mph. Booster on full, and it slipped while going over the switch points, then the driving wheels slipped.

No idea as to why it took so long to shut off the throttle.
Kevin

co614 · **Posted:** Fri Jan 04, 2013 9:23 am

John Hillier says it well. From my experience the most important single ingredient in being able to recover quickly enough to keep sufficient forward momentum when in a really hard pull ( say under 9mph with a full tonnage train) is to be hands on the throttle and anticipating a slip so that reaction time is nearly immediate.

One of the links John posted was the 2101 taking a full tonnage 24 car long Chessie Steam Special train up Sandpatch in 1977. I remember the trip well as it was a real challenge for the engine and many had doubts she could make it with that train. Fortunatly all systems ( emergemcy sanders, booster, rail washers, capable fireman) worked as they were supposed to and I was able to quickly recover from the numerous slips on the way to the summit. If any one of the critical components not worked we'd have undoubtedly stalled somewhere on the way up.

As to Blue Peter's incident it would appear to have been a perfect storm of a number of mishaps coming together in perfect unison to cause that awful event. Sure glad both the engineer ( driver) and the machine were able to make complete recoveries.

The primary reason steam locomotives carry the female gender is that they are as unpredictable as they are attractive!!

Ross Rowland

prosser · **Joined:** Fri Dec 21, 2012 7:32 pm **Posts:** 46

p51 · **Posted:** Fri Jan 04, 2013 4:17 pm

prosser wrote:

Bill Purdie certainly was a steam man.

Truer words were never written!

J3a-614 · **Posted:** Fri Jan 04, 2013 6:32 pm

P. Rosser is right about the Bill Purdie profile being in Trains; I don't have the issue in front of me, but I think it might have been in 1977. One thing I do recall was that in addition to the reaction of Mr. Purdie to the collapsed dry pipe in 4501 was the account of the heroic measures he and the steam crew took to get the 4501 running again. This included cutting out the old pipe and installing a new one, in sections, through the dome. It meant working in a still hot boiler, with torches that consumed so much oxygen that air had to be blown in so the men could breath. This sort of thing might have been semi-routine or at least not a big deal in regular steam days, but can you imagine the squawks one might get from some managers today about "excessive risks" and "excessive costs?"

Ross Rowland's comment about the feminine nature of steam locomotives reminded me of this comment by Kramer Adams, in his book "Logging Railroads of the West" (Bonanza, 1961):

"The engine was a 'she,' scissorbills or greenhorns were told, because it wears apron, binder, bonnet, cap, collar, hood, hose, jacket, muffler, petticoat, pumps, sash, shoes, sleeve, wrapper and yoke and eats twice what she's worth.

"The logger was able to add another reason. His locomotives were called 'she' because like women, they'd rather not admit their age after 20 years."

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

We men should also always love women, one of the reasons being that they put up with all our bad jokes. . .

JasonA · **Joined:** Sun Apr 04, 2010 12:15 pm **Posts:** 44

Quote:

P. Rosser is right about the Bill Purdie profile being in Trains; I don't have the issue in front of me, but I think it might have been in 1977. One thing I do recall was that in addition to the reaction of Mr. Purdie to the collapsed dry pipe in 4501 was the account of the heroic measures he and the steam crew took to get the 4501 running again. This included cutting out the old pipe and installing a new one, in sections, through the dome. It meant working in a still hot boiler, with torches that consumed so much oxygen that air had to be blown in so the men could breath. This sort of thing might have been semi-routine or at least not a big deal in regular steam days, but can you imagine the squawks one might get from some managers today about "excessive risks" and "excessive costs?"

Typical Boilermaker work, goes on everyday in Steel Mills and powerhouses. I think the worst I have ever been heat wise was 135 degrees, 140' in the a firebox, welding 9018 tubes in the division wall, we were also in a pic, suspended by two 5/16" cables. Working on a hot furnace is cool too, sometimes you have to work with supplied air because the CO is off the scale, was stops on the meters at 9999.

Fun stuff, I kind of miss it.

Jason

prosser · **Joined:** Fri Dec 21, 2012 7:32 pm **Posts:** 46

Another video of what could be classed as an uncontrolled wheel slip is on the Santa Fe 3751. The tape was called Steam Across America. When the engine passes the tower leading into LAUPT, it begins to slip then seems to go into a uncontrolled slip. It continues right to the scene change. Judging by the rpm's, she was rolling.

P.R.

Frisco1522 · **Posted:** Fri Jan 04, 2013 9:54 pm

I've seen that video also and fortunately the slip speed didn't get excessive. It looked to be a case of the engineer foaming or something and not paying attention. I think that was the trip where they worked her hard through the tunnels and made a big mess.
Everybody has to start somewhere.