But I put it in here for the hypothetical part. A friand of mine and I were just yammering online a few nights ago, and we got to the part about the modern steam survivors and their diesel tagalongs. He proposed some kind of system converting the Johnson Bar’s movements to the throttle control on the diesel, kinda through the remote system and probably through some fancy sensors. Ofcourse, the airbrake is already handled, the Dynamic if the engine has one would need to be manned somehow though. Niether of us knowing all that much about steam or diesel throttel controls, what kinds of compatability issues stand in the way?
The big joker in the deck is that steam locomotive speed/power is controlled by two, separate levers.
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Throttle. Controls steam supply to cylinders. Usually either wide open or closed.
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Reverse. Controls cutoff, allowing for steam expansion and more efficient operation.
OTOH, the diesel has a single power control.
While it might be possible to tie the diesel controls to the throttle and reverse levers, it would take:
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Sensors on the lever arcs, rugged enough to stand up to steam locomotive cab environment.
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Dedicated microprocessor and beaucoup lines of custom code.
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Servos on the diesel’s controls.
Translation, several $K, and a LOT of Beta testing to get it somewhere close to right (more $K.)
The Clinchfield came up with a better answer several decades ago. Just put a separate diesel control stand in the steamer’s cab. Theirs was home-made.
BTW, there’s no requirement for coupled diesel and steam locos to be run like a model train DCC consist. Usually, in helper districts, the helper runs wide open and the road engineer controls speed by controlling the power output of the road locomotive.
Chuck
Here are a few links to help you understand the function of the “Johnson bar” a little better.
http://steamlocomotive.com/appliances/valvegear.php
http://home.roadrunner.com/~trumpetb/loco/rodsr.html
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Been mostly done already, I believe. Back in the 1970’s or so when the Clinchfield RR was running steam excursions with a pretty ancient and not very big or powerful 4-6-0, they took to putting a couple F-something B-units behind it for additional power - they were painted a dark green as I recall, so they didn’t stand out and looked like baggage cars or something else innocuous. Anyway, as it was reported in Trains - and perhaps other publications - at the time, the Master Mechanic rigged up something in the steamer’s cab to control the diesels from there. I’m not familiar with the mechanical or electrical details, but you could look it up, I suppose, or maybe someone else here can furnish that - try also over on the Locomotive and Steam Forums here. I also believe something similar has been done elsewhere - likely on a tourist line, perhaps one of the “Thomas the Tank Engine” operations - but can’t recall specifically where. I doubt that UP or any of the other big-time steam locomotives has done that, though.
- Paul North.
Rather than trying to directly link the differing controls of steam and diesel locomotives as is done with M.U. operation, it might be easier to apply a device that would measure the power output of the two different locomotives, and then would signal each of the differing control groups to adjust the power outputs so they match.
The Clinchfield experiment was not really an M.U. system for steam and diesel. Instead, it was directly manually operating the diesels from the cab of the steamer, and then manually operating the steamer at the same time. It was like a steam/diesel double header, but with one engineer able to reach both sets of controls for the two locomotive types.
On those long Clinchfield excursion trains, I don’t think the steamer was doing much besides making smoke. Those two F-units were wide-open much of the time. So there was not a great need or challenge to actually coordinate power.
Analogous to the operation of DPU’s today. One engineer controlling multiple power units from a single control location. While DPU controls are more sophisticated, the functional requirements are the same.
It would be analogous in the sense of one engineer controlling multiple units from one control station. But in the case of the Clinchfield application, and unlike DPU, there was no connection between the controls of the diesels and the controls of the steamer (other than air brakes). I guess in that sense, it would be like a hardwired version of DPU operating in the non-synchronous mode.
Every steam excursion I have been on has the diesel along only as protection power in case the steam engine has a mechanical failure.
On the last UP excursions I enjoyed, I asked and it was explained that the diesel was there only for that specific purpose, and to provide HEP if the power car had a problem.
Both the 8444 and the 3985 are quite capable of pulling all the excursion cars and the diesel by themselves, and the diesel is quite capable of hauling the entire consist also.
In normal running, the diesel is in neutral and not pulling.
Both the 8444 and the 3985 have the appropriate air hose connections to allow the steam engineer to control the braking system, the diesel is set up in “trailing” mode.
The necessity of MUing the steam to the diesel for pulling power escapes me, as the diesel is only there for protection power or HEP.
The purpose of steam excursions is to ride behind a working steam engine doing all the pulling, if the diesel is on line, why not simply use a unit equipped with Locontrol, put the engineer in the steam engine with the chest pack, and let him run from up there, saving hours on the steam engines boiler time?.
Ed, the Clinchfield operations discussed above had a 2-6-0 pulling 2 “baggage cars” and a bunch of coaches - far more train than it could start, never mind drag up the Clinchfield’s Blue Ridge crossing. If the “baggage cars” hadn’t been B-units the steam excursions would never have left the station.
I agree that either 844 or 3985 can handle a long train without help - but not all excursion steamers are modern superpower. Back when the Grand Canyon Railway was running 2-8-0s, the diesels were pulling, too - or the train wouldn’t have made the climb from Williams to the South Rim.
Back to Clinchfield #1. The diesel throttle and reverse were totally separate from the steam controls, mounted on a home-brewed control stand. MU cables ran from the steamer’s cab to the lead diesel, which reacted just like the first B unit in an A-B-B consist. As mentioned above, on the heavier grades, #1’s primary duty was to make smoke.
Chuck
Except when things happen like the steamer isn’t capable of handlign the terrain (4449 getting helpers through Tehachipi, 587 in Applachia,) or the host railroad wants the engine speeding things up (though usually, the diseasel is on point in that case)
Admittedly, you’ve been on more Class 1 excursions than I, as the last ones wrapped up before I was out of diapers. But one of the things I was told was that a few excursions had Diesels on to assist with braking in dynamic. It doesn’t make sense to me either, since the steam engine is freewheeling at that point, but I’m more inclined to beleive a railroader who told me that. (Now, obviously, most trains are flat land and won’t need a dynamic for their short length, but)
I’m pretty sure that’s been done before too, letting the steam engine take a breather in places where no one is looking. And I’m reasonably sure that 765 has the remote or remotely located control stand. The problem as my firend and I understand it, it that still requires a crewman to run the thing, versus one engineeer trying to juggle two different locomotives.
Mostly though, I’m using this as a chance to learn ssomething about engine control. [:D]
I think both the CPR Hudsons (2816 and 2860) that are running here in Canada have a control stand to run a diesel if one is included. Even then, though, the steam engine is doing all the work most of the the time.
The dynamic brake on a diesel is particularly useful on steep downgrades, saving a lot of wear on brakeshoes and wheel treads. In the “good old days” trains would sometimes have to come to a stop part way down a hill to let the brakes cool down.
Having the extra power available can help maintain speed on the uphill grades, sometimes important on a mainline to avoid delaying other traffic. Using the diesel to assist will also reduce the boiler’s water consumption for those times when the next good water is 150 miles ahead. The diesel also pacifies the operating personnel, who have no understanding of how capable a well-maintained steam locomotive is operating in the type of service for which it was originally designed.
John
The Clinchfield control unit was actually the hostler control that came from a B unit, and simply served as a remote control for the diesel helpers in the consist.’ It can still be seen today at the B&O museum in Baltimore.
Ross Rowland’s proposed ACE3000 Steam Locomotive demonstrator was to have had the capability to M.U with diesels (and multiple ACE3000s) via a computer assisted throttle system…