On the PRR T1 thread, Mr. Rowland relayed a few experiences running boosters. Thank you sir for answering my questions on that thread. This has likely been covered on here before, but I thought it would be best to start a new thread. If this is redundant, then the moderators are welcome to remove this thread.

Here is a neat, basic site on booster motors. It answers some questions about "clutching", etc.:

https://www.railwaywondersoftheworld.co ... oster.html

There has been plenty of writing about railways removing the boosters over time. One can see that would be advisable, if the loco was running in an area where the booster was rarely or never used. The positioning of the booster motor suggests some maintenance headaches.

Here is another site with some in-depth operating information. I have not read through it yet, but there appears to be some useful data:

https://railroad.net/the-locomotive-boo ... 75467.html

If others have some hands-on experiences, or if Mr. Rowland wishes to restate his experiences or add more, that would really be appreciated. As a good friend often says, there are so many nuances to locomotive technology that we are losing, or have lost.
Thanks again, and thanks as always to RyPN for providing this excellent forum.

As with the superheater, various approaches to 'using boiler capacity at low rotational speed' or to assist low-speed starting were tried (there is a category in Wiener's Articulated Locomotives) and only the properly-thought-out approach solved the issue well. In a sense the booster also had to wait for the second form of Delta truck to have the right "environment" for it to work.

One of the significant reasons for the adoption of an 'auxiliary locomotive' was the introduction of short limited cutoff "for economy" -- take for example the PRR I-1 with 50% maximum long cutoff, relying on slot ports to be able to start. The initial premise of a booster was to provide an additional 'adhesion axle' for starting a train a given locomotive could pull once it came up to speed -- accordingly the earliest boosters were limited to somewhere around 15mph maximum, roughly where the increase in steam through the booster would match the increase in steam that could be practically used in the main engine for acceleration.

The practical Franklin booster was the result of extensive work by someone at New York Central, who had a good idea of what needed to be done to make a relatively complex set of functions not only automated in a way comprehensible to enginemen and not distracting from the job of locomotive and train handling, but also relatively immune to breaking, misadjustment, and improper shop procedure. This is why the only 'cutoff' on the booster engine itself is essentially in the wiredrawing of admission (similar in principle to the practical operation of "Franklin System type D" poppet valves -- it would be much more effective to have variable cutoff on what is essentially a high-speed engine if the idea is to be able to cut the booster in and out as that "additional traction axle" were needed, but it would involve no less twiddly a control as that on a de Glehn-duBousquet compound, and would be difficult to 'automate' with compressed air as the various sequences of operation of the Franklin booster were.

As Franklin refined the booster (and conducted its patent suits against companies like Bethlehem, only resolved in the early Thirties) the speed the device could be kept in gear increased, up to about 32mph. I suspect, considering the steam the thing would be drawing at that speed to produce high wheelrim torque, that this was to increase the speed before the controlled disengagement would occur, in case the booster were needed again with the locomotive moving.

You'll see references to the 'reversible' booster. I thought for many years this referred to the ability to operate the booster itself in reverse, to aid backing -- this is not the case. It means the booster engine is reversible to help kick the transmission into disengagement if it should stick, for example if momentarily 'hydrolocked' due to inadequate preheating out of gear, or to operate the engine to clear any blockage. (It is an interesting engineering exercise to contemplate what an actual reversing booster would involve, and how it would be controlled...)

When you find a booster in a four-wheel truck, it acts just like a two-wheel booster, and this accounts for those trailing trucks (as on the J1 Hudsons) that have a larger rear wheelset -- that's mechanical advantage for the booster engine.

Southern Pacific found a very good use for the booster very early (in conjuction with a good feedwater heater). Instead of using Pacifics, SP rebuilt some high-drivered Atlantics with short stroke and small valves (hence low inherent water rate, but prone to stall and not have much low-speed horsepower) so that they could run up to 229 miles without taking water. A pair of subsequent conversions were good enough to get Daylight paint (and to be memorialized in a book about 'trains of the forties' as being able to start and run something like a 24-car wartime consist... as impressive at publication time as it was then.

What changed was, first, that Eksergian et al. devoted interest to correct locomotive balancing and reciprocating-mass reduction, and second, that the modern age of high-speed power took over from the drag-era of early Woodard and the first stabs at 4-8-4s. Even by the early Thirties the combination of lightweight rods, disc centers, relativel small bore, and the longer stroke permitted by better balance (up to 34" in quite a few Lima engines) meant that you could use more of the steam in the cylinders even at low speed -- and it would not take much improvement before the added weight, complexity, and above all cost of the complex booster became less valuable.

There were few engines that, practically speaking, would benefit from a good booster more than a PRR T1. Yet only one of those engines had one, and it was removed even while the engines were still having their worst bugs worked out. More to the point, even after it was well-established that the short-stroke T1 was prone to stall with only slight overloading... no booster was ever retrofitted to one.

On the other hand, the Q2s had them, and they weren't removed to my knowledge so presumably were used regularly, not just to get the equivalent power of a 2-6-6-4 with a rigid frame, but to give a heavy train quicker starting and low-speed acceleration. I suspect somewhere there are accounts of exactly when and where the Q2 boosters came to be used... during the comparatively short time the PRR actually used these engines in high-speed manifest freight service as originally intended.

Thank you for the reply, Mr. Ellsworth.
Definitely more reading to do, but I am not clear on how the boosters cut out at certain speeds? Over-riding clutch?

Keep in mind that the 'normal' cutout is produced when the booster control latch is 'knocked down' by the engineer -- this spills the control air and the clutch and idler gear promptly disengage (assisted by being kicked out by rotation of the driven axle).

My advice is to download and read the Franklin C-1 and C-2 booster manual ('instruction book' 102-A) that Claude Bersano put up on his site:

http://users.fini.net/~bersano/english-anglais/locomotive_booster/locomotive_booster.pdf

The control system, with a delightful fold-out diagram of the arrangement, is on pp.47-55. The arrangement giving the effect of 'lengthened cutoff for starting' is pp. 12-13. The 'geometry' of the transmission arrangement is pictured nicely on pp. 17 and 34-35.

Note that on the C-2, the booster latch is 'interlocked' with the Franklin Precision reverse, so that winding the engine toward longer cutoff will automatically 'knock down' the latch, spill the control air, and release the idler as mentioned above. Since even with 50% limited cutoff you would not keep the gear 'down in the corner' for very long during acceleration, this was a reasonably "automatic" method of disengaging the thing when used as an 'extra axle' starting or adhesion aid.

In the "Operating Instructions", which is in charming 'catechism' form, note #4 (p.4)
which asks "Should the Booster be used when the train might be started without it?" Franklin's answer is unequivocal: "Yes. Always use the Booster to start the train, whether a full train or not, as it will enable road speed to be reached in a shorter time." [Note that it may be that 'road speed' for a locomotive equipped with a type C booster might not be all that fast...]

Franklin notes that the booster can be cut in at any speed up to about 12mph. They warn strongly about doing so above that speed, as (they use more euphemistic language) you will grind much more than a pound trying to mesh the gears above that speed. Likewise they note that the type C should not be kept engaged above 21mph.

There are a couple of notes about what to do if you stall with the booster engaged. You can back up Slowly (emphasis and capitalization in the original) for a slight distance. Otherwise, you must move the engine slightly forward with the latch 'knocked down' to ensure the idler comes fully out of mesh. I get the impression that you're supposed to let the train roll back a bit with the independent set, then set the train brakes, Slowly roll back the distance needed to disengage going forward, then with the booster latch knocked down move the engine forward against the slack enough to get the gears disengaged. (The train can then be backed down the grade without damage...)

I do not see the governor arrangement I thought I remembered that would knock down the air when the rotational speed of the trailing-truck wheel exceeded the equivalent of 21mph for the type C. That does not seem like a difficult device to design, fit, or keep maintained. Perhaps that was added on the type E, for which I have not seen an instruction manual.

Incidentally, a very interesting service history of one of the more carefully-conducted booster tests was that kept for the 'articulated trailing truck' applied to LNER Ivatt C1 #1419 (LNER #4419. You can read the details by scrolling down here:

https://www.lner.info/locos/C/c1.php

Excellent Franklin instructions. Thank you.
Clutch operation is very clear.
Yes, those gears were not meant for "on the go" shifting.

You are working in the roundhouse and one of those ol' hogs is rolled in. The engineer's report says "loud clunking sound coming from booster motor!" It just becomes apparent that what could have been a hard day is going to get a lot harder, dirtier, and greasier! Oh the language!

That's what the next shift is there for.

Note that Franklin provides specific instructions on how to cut a booster over to run on air for testing. One tidbit from the English experience is that the booster attachment to the trailing-truck frame is only at three points in a cast frame, which would facilitate swapout...

Part of an answer to a report that 'booster makes clunking noise' is whether or not the railroad's operation 'uses' the booster regularly for starting, as the company's liturature exhorts, or as an 'emergency aid' to be used only when needed. In the latter case, after enough troubleshooting to verify that the 'clunking' isn't something causing trouble in normal running, like an idler not fully releasing or one of the mounts broken or sagging, the 'simplest course' may be just to tag out the booster until a scheduled shopping makes time for more formal attention.

If the former -- it may make sense to have engine assemblies, perhaps even whole boosted trailing trucks made up ready to be swapped in quickly, with repairs than taking however long they do, on the bench under controlled conditions, while the engine goes back on the road operational. (I suspect the cost of these things might not frequently permit that luxury!)

The mechanical-servo 'automatic operation' of these things was always the thing that gave me the most worry. Even if there is an approximation to clean, dry control and power air... all those little operations and dashpots have to work in the correct order, often with no manual backup to help it along. There are amusing notes about how PRR had to create a sort of :clean room" for things like Baldwin diesel injectors in the Forties -- and even then, the relative conditions there were not exactly conducive to assured reli8ability. (It was mentioned to me by someone who maintained marine 567s during WWII that if you got a fingerprint on parts of the injector, it could not be assembled...)

As an alternative to three-cylinder power or additional driver axles for staeting, the booster (and the auxiliary locomotive) were useful. As soon as better balancing and lightweight rodwork became practical...


As a parallel, consider the Southern Railway's long dalliance with the idea of multiple motor tenders for hump power. Looks like a real good idea! Southern in fact got to the point where they tried not one, but two six-wheel tender boosters under one tender. That it is as well hidden as experience with front-end stokers should make us, rightly, think...

Thanks again for the feedback. A friend who saw this thread -- a life long railroader -- reminded me of locomotives within driving distance that still had boosters. That might be a trip, or two, and with permission and overalls, an interesting crawl under some of those old hogs.
Even in my lifetime, there were still some steam shops in operation, including the CNR Stratford "Big Shop," CNR and CPR roundhouses in Toronto, and loco facilities in Hamilton. Sadly, I was too young to visit those shops, and not bright enough to hunt down some of the "old heads" who worked at them to get information.
The closest I got was the CNR Spadina roundhouse in Toronto when No. 6060 was maintained there. There were occasions to see superheater repairs, piston ring repairs, brick arch work, and to look over other attributes like the exhaust steam injector. Of course, that is nearly 50 years ago and most of those fellows are likely gone now.
So much to learn -- so little time to learn it!
It is always nice to hear from those who have the hands on experience about running steam locomotives and managing the various appliances.

This has absolutely nothing to do with boosters, but is just a nice bit of video. Some good "in the cab" scenes, and some recovery on wet rail -- all in a good day's work.
I recall a trip in the late-70s with ex-CPR No. 1057 (4-6-0). Westbound on the Toronto Hamilton & Buffalo out of Hamilton, with six heavyweight cars, the engine lost her footing on the grade up the Niagara Escarpment. They had to double the train, taking half to the siding at Summit (aptly named) and going back for the rest. Cause of the slippage was wet rail and an eastbound freight through the night with several loads of oily scrap steel that dripped oil on the rails! The crew did a great job and it made for some interesting sounds.
Nice to see the Consol in the film. Those old hogs do not get all the accolades, but they did a great job for decades and still can. A friend talks about his grandfather running them for the Grand Trunk. They were cross-compounds at the start. His grandpa said when they simpled and superheated them, they made real engines out of them!

https://www.youtube.com/watch?v=X7WNdOhNxec