Tugging at the steam locomotive throttle handle

Trains Magazine Steam & Preservation
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Perusing the Web for steam locomotive cab-ride videos, I have seen many of a steam locomotive driver “tugging” at the throttle handle to make changes to the throttle setting.

The impression I have of the throttles in an airplane, even one of the old multi-engine “prop-liners” along with those in even a fairly substantial motorboat is that the pilot places their hand on the throttles and moves them smoothly. It appears that a steam locomotive driver has to tug on the throttle handle two or three times to get it to budge?

Reversers had long changed from the dangerous “Johnson bar” setup, where friction forces in the valve train could break a hand, wrist, or arm operating that control, to controls with mechanical advantage such as the screw reverse to controls with “power assist” such as a steam-operated reverser. I have seen video drivers “winding up” a screw reverser to obtain the long cutoff needed to start the train, but it appears that the reverser control moves freely. Not so with the throttle.

To excuse a pun, “what gives” with steam locomotive throttles?

2

Paul,

The steam engine is unlike the internal combustion engine because the throttle has complications with the steam boiler pressure not usually considered.

I have disassembled and reassembled the entire “front end” throttle of Pere Marquette 1225 which is a modern 2-8-4 berkshire locomotive and uses a multiple valve front end throttle. The parts in this assembly are massive including a huge quadrant with throttle arm suspended from the back of the boiler. This in turn moves a long hollow pipe through runners to a steel compensating lever on the side of the boiler. This compensating lever in turn moves another similar hollow steel pipe which actually moves the external throttle lever of the “multiple valve” steam locomotive throttle.

The multiple valve throttle is really just a camshaft which opens seven or so independent throttles in the superheater header. As the cam rotates a small pilot throttle is opened then another cam opens a larger valve while another cam follows opening a third valve and so on in increasing succession. (Kind of like a musical trumpet with its valves in a row.) All these parts are also acted upon by boiler steam pressure trying to escape.

Further considration in the throttle mechanism is that as the boiler steam is exhausted by the cylinders - the exhaust draft up the smokestack creates forced draft effect upon the fire in the firebox - the result is the engine is started and the momentum of the heavy drive wheels and rods reacts against the track - as does the forced drafting of the fire in the fire box at the same time.

Locomotive traction is another consideration - as is the slack take up effect between the cars - taken up as the train goes into motion. In passenger train service there is also the consideration of the shock or jolting of passengers to be con

3

So the essence of what you are saying is that crews had been OK with power assist for the reverser much as motorists are OK with the automatic transmission, but applying power assist to the throttle is like the Toyota situation where people were blaming runaway cars on an errant computer-controlled throttle?

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Paul,

You could say that “power cylinder throttle” scared off everyone because of possible failures in operational mode.

Although with the railroad steam locomotive many system failures could be catastrophic. No machine of the day was equal to that hurtling steam powerplant operating at speed with such fire and pressure contained within itself and such massive steel load in tow.

The Toyota case was a seriously dangerous situation - of the car running out of control in unsuspecting ways - in the hands of innocent and unsuspecting people.

In the operation of the steam locomotive much skill was required. Some locomotive systems were for safety reasons redundant. Such as the water supply to the locomotive and the water glass reading to the steam boiler. A failure of one of the two water supply systems was cause for alarm - the failure of the second system was just downright dangerous. Many serious boiler explosions resulted while very skilled enginemen were in full contol of the functioning steam locomotive.

The engineer’s manipulation of the throttle, reverse, sander, train brakes and injector was among the most complicated mechanical and intellectual functions of the human mind. A symphony of movement.

At one point in my life I taught Industrial Education and I also hold among many degrees, a Masters Degree in this for public education from Wayne State University - well I can tell you that modern studies of the functions of the human mind indicate that the intellectual capacity required to perform many such trade occupations are as demanding as exacting careers in medicine, law and engineering.

The observation and formation of judgements, the observation and calculation of data and reference to knowen facts and careful execution of all this was as advanc

5

It might be useful to consider at least two approaches to this question that have value. First, though, we might address what it is that the ‘pilot’ valve in a multiple throttle is there for. It equalizes the pressure on either side of the poppet valves, reducing the pressure resisting the cam motion to very little. Putting proper (modern) material in the longitudinal contact bearings in the linkage, and using proper joints to prevent lost motion and slack, will probably go a long way toward making the opening and closing of a good multiple throttle both easy and positive.

The air-operated throttle on the T1 was not an ‘assist’, it was a full servo (equivalent in principle to a Ragonnet reverse, where there is no physical linkage from the cab control to the device, only a hydraulic/pneumatic one). I have not verified that the ThrottleMaster worked the same way, but I suspect it did. Here, the linkage from whatever physical throttle lever to the ‘control’ cylinder arrangement can be short, positive, and completely countersprung (as automobile foot throttle linkages are) so that the arrangement will be self-closing but, when necessary, both quick-acting and proportional. Servo assist on a normal mechanical linkage would require elimination of the mechanical clutch locking, which in turn would create the risk of sudden and unexpected motion of the cab lever under considerable power at considerable speed, a major hazard.

The Wagner throttle was understood, by about 1912, to be as precise a method of controlling even large and heavy main throttle valves, against considerable pressure differential, as was needed for most work. In this design, the tapered pilot valve is concentric with the main valve (which floats in its cylinder without any physical connection or linkage); the steam pressure very neatly forces the valve to follow the pilot without overshoot or oscillation, while keeping the force to move the pilot very low, no more tha

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So when I see video of restored locomotives with the driver giving the throttle two or three quick tugs to budge it, I am to assume these are locomotives without these devices or perhaps in need of the linkage being oiled?

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At a museum I used too volunteer at we had an alco s 1 diesel switcher with a " steam throttle " rather a throttle with notchs. We were told the old steam heads preferred the diesels with steam thottles. In any event we would release the air brakes and pull back the throttle and slowly roll out of the yard. Once clear of the yard limits, we would pull the throttle back, an the old girl would be belching fire and smoke. We would quickly get to track speed ( bout 15 mph ) and would have to back it on down. Not exactly one of the zephyrs, but a fun way to spend a Sunday afternoon.

Never knew if all early alcos came with this kinda of throttle or if these were an option?

She was built for the US government, worked at the Savannah nuc plant and worked her final days shoving rocket parts at NASA in titisville FL.

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From the description, it sounds like the S1 was equipped with an air throttle, probably not original equipment since Alcos had GE electrical gear and Hermann Lemp was with GE when he developed his control system. Baldwins were built with air throttles, which made them incompatible to run in multiple with locomotives from other builders.

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I am not an expert on Diesel Locomotive Air Throttles.

The way it should look. Manual Throttle. Alco S Series.

https://s-media-cache-ak0.pinimg.com/736x/80/83/63/8083636fe2cb5a896d572243c3ae8fd3.jpg

Not the best view . Notch Throttle used in MU applications.

https://i.ytimg.com/vi/do9CNax0kuk/hqdefault.jpg

Reverser Handle NOT in place.

https://www.youtube.com/watch?v=do9CNax0kuk

Oil Lube pressure had to reach 40 lbs before start button released to overcome Low Lube Penalty.

AFAIK. a true Air Throttle set up uses compressed air from Engineer’s ‘Throttle’ in cab to actuate Governors on lead and trailing locomotives, the latter thru air hoses unit-to-unit. all throttle/governor actuation by air pressure variance only.

On some Single Alco Switchers w/539, and probably others of the kind, the Throttle handle was directly connected by mechanical linkage to the Diesel Engine Governor on side of Engine. No air in throttle circuit at all.

The movement of Throttle in cab WAS necessary during Downward Transition.

On Electric Throttle, the Throttle handle had Notches and operated Governor electrically, but there was an air piston to move the Governor link itself, and, the electric portion allowed locomotives to MU thru Jumper Cables.

http://www.schenectadyhistory.org/railroads/manuals/tp107a/

The following is from attached link, below.

QUOTE.

Earlier RS-1s had an SI governor, replaced in later production with the PG. Both used the

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Ndg, the top picture was the throttle set up I was trying to describe. This is a air throttle? We had a rs1 with the notched type throttle. It was described to us as a " emd " type. Never knew if this was accurate or not.

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I would say, from the factory, as built. Yes.

Anything can be kitbashed, even in real time.

I have never seen the air-operated motor as in previous applied to 539 Governor w/ notch throttle as for MU. 'cause I never looked under the hood of one so equipped, nor understood the operation 'til I read above data.

Some Ss had manual shutters all around. Some later had air shutters.

I assume the throttle could not be ‘advanced’ until air pressure was pumped up a bit on starting.

Some Ss had a door within a door in front side of cab wall into engine room. The smaller door had a cabinet w/fire extinguisher inside.

About 45 years ago I bought a 1956 Ford/Mercury 3/4 ton truck w/ DODGE 318 V8 Automatic for power, from a car foamer kitbasher.

Automatic, and clutch pedal still in place. Dimmer switch on floor, to left.

Mais, Je Digress.

Find a 539 and look under hood, left side re governor.

Have to go.

Thank You.

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. thanks for all the insight…and how we miss the dimmer switch and the no draft windows!!!

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Don’t miss the floor mounted dimmer switch at all.

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I just awoke as the Kat was having a fit! 18 inches new snow and he wanted to go out and Preen on the porch for his fans. He has been wonderful since I retrieved his Contact under the Fridge, cleaned it, and put it beside his dish at supper on a nice piece of Satin from my Mother’s sewing kit.

He actually stopped stuffing his face, and came over and rubbed against my leg and purred Thank You, then let me warm his tummy on my lap, wriggling around for comfort, His.

Anyway.

I miss the No Draft window, too, and side windows that were vertical so drops of rain won’t fall on your arm at stop lites. Also miss those air vent doors down by clutch and psgrs feet that could be opened to let in fresh air by the TON.

Regular and High Test gas, and the pumps that went ‘Ding’ with every gallon pumped. The old air stand at service stations, some were illuminated, and had crank on side for pressure and went ‘Ding’ 'til pressure equalized in tire.

Hose you drove over, went ‘Ding’ inside.

No Power Brakes and 20 million turns lock to lock, parking. Not so fun.

Parallel parking uphill backwards at night w clutch and manual steering.

Vacuum wipers SUCKED on hills.

DC Generators and Regulators let lights go brite and dim if heavy load from idle.

You could remove battery caps and add distilled water. Batteries WILL explode WITH VIOLENCE when gassing by sparks from jumpers, as O2 and Hydrogen present. Been there, done that, ruined coat. Snow handy to apply to face.

Had to crank many old trucks I had to get them to start if battery low. Some old equipment had 800 cu in engines and a Mag. No Starter, and a Crank, Retarded spark to start, manually. and choked engine pulling crank thru to inhale gas for start.

Fairmont Motor Cars Crank Start, engine reversible, and the real old ones had spark coils w/vibrating points and drycells for power.

P

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Was the owner of 2 International Travel-Alls, purchased back to back. The choke lever was an absolute necessity. Had the same box of goodies, fuses, bulbs, spark plugs, oil, oil and more oil and the essential ceramic plate replacement. The plate would break or “burn out” and then no start. Easy fix. Loved those vehicles. They became the Chevy Suburban.

Both had a rear facing bench seat in the back and you could roll the back rear facing window down, or by power from the front. My 3 kids would always, always without exception sit back there, more often with the window down and wave away at others and have a good time. I put in an intercom with a handheld microphone up front so I could give 'me heck when needed and they could not pretend they couldn’t hear me.

As in “Settle down back there”…or “Oh look, cows”

No seat belts. Wonder how we all survived. 2nd one had lap belts, sometimes on, most often not. Not the law yet, but recommended. Not like that today. I do see kids up here in the back of pickups still, RCMP will stop them if they are unlucky.

-37 here last night…house booming and bumping…nails popping outside and in the roof…little sonic booms…dog gets very upset by it.

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I drove standard transmission cars from 1975 to 2011, finally went to an automatic with the new Hyundai, after 20-plus years on the job repairing copiers I’d just about clutched my left foot to hamburger! All stop-and-go, all local. Ow.

Lady Firestorm drove a standard too for many years, gave it up when she bought her Saturn, but still would have preferred the standard.

For all practical purposes though, the little “bump” you used to get in gas milage from a standard transmission just isn’t there any more. I can still drive a standard (hey, it’s like riding a bicycle) but really don’t miss it.

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Thank You Sirs!

Nowadays I would drive automatic, as my knees are shot.

As Mr. Firelock said, I once took my truck to the Coast and got stuck in traffic. Rush hour is 24/7/365 NOW! and they LOAD COAL at the Mines faster in Unit Train Rotary Drawbar Service.

I used the clutch thirty times in half a block to save holding it in and tiring my leg.

Out here, once you get it in High, you don’t touch the clutch for a hundred miles, brakes neither if little traffic., and planning.

Here is a FWD I had back when. A True US Army M37, ( there were Canadian built Versions ) and I used it all the time.

Big Tires 9.00 x 16? split rim, TP 40 PSI.

Lots of fun but very hard on fuel.

I applied Star to doors using Mactac or whatever it was called. Original Stars had been scraped off. Converted electrics to 12 Volt and installed Alternator, as factory 24 Volt Generator Bad Order. Replaced Distributor w/ one from 1954 Dodge truck and installed in-line resistor to save points.

Put in 2 x 12 Volt batteries, as left starter 24 Volt. It had a CRANK, and a hand throttle. Starter PEDAL was up on hump below windshields. Batteries under right seat.

To continue Railway theme, a bit.

From the inside looking out.

Checking Oil in Tender Tank.

[IMG]ht

18

RME

Regarding the T1 air actuated throttle with cylinder similar to locomotive reverse?

I have examined all the Pennsylvania Railroad T1 duplex 4-4-4-4 photos of all the various engines, and can only observe the standard steam locomotive multiple valve front end throttle with compensating linkage - every photos shows this mechanism running along the side of the boiler. All photos also show the standard pipe operated quadrant on the locomotive backhead. In fact this is the case for all the duplex engines and the steam turbine.

Possibly you could explain your assertion for the air throttle and cite the reference.

  • Doc
19

Reference is the PRR detail drawing for the Franklin Precision air throttle. (I don’t have the number handy where I am right now, but it’s in the T1 Trust repository; I originally obtained it courtesy of Bill Burket of Altoona.)

The cylinder is not precisely ‘similar to locomotive type reverse’ in that what I originally expected it to be was a ‘booster’ for mechanical movement, sensing any slight movement in a ‘normal’ mechanical linkage from a grapevine throttle and providing proportional quick-acting force amplification (I suspect also providing substantial damping against overshoot, inertia, and other forces in the linkage and throttle mechanism). It would be interesting to have Prof. Milenkovic’s opinion on the mechanics of the device as the drawing (which is a Franklin drawing given a PRR number) shows it.