Canadian National & Grand Trunk operated more 4-8-4 steam locomotives then Canadian Pacific.

[Engi1487]

I dont have a number for how many 4-8-4 type steam locomotives (200 plus I remember sort of) where operated by Canadian National and its subsitary Grand Trunk Western, but I know that they operated more then their main Canadian rival railroad, Canadian Pacific, which only had two made for use on the corridor line between Toronto and Montreal due to the heavy weight of the overnight passanger trains.

I understand why many railroads of the steam era didnt have many or none of a certain steam locomotive type and wheel arrangment like others, as it might not have need for it. Canadian Pacific had many successful types, but was there a logical logistics buisness desicison as to why the CPR decided to try only two 4-8-4s by building their own, compared to the 200 plus 4-8-4s that CN made and operated? Why not turn a 2-10-4 shelkirk into a 4-10-4 (does not exist I believe) and use that?

So to summerize, why did CN have and need use of more 4-8-4 steam locomotives then the CPR did at the time of the height of steam power on their railroads in Canada?

[M636C]

Simple.

Canadian National was formed from a number of railways that had gone broke. The general standard of their main line track was lower than that of Canadian Pacific.

To get a locomotive of suitable power, CN needed to use 4-8-4s where CP were able to use 4-6-4s because of the higher allowable axle loads.

CN had only five 4-6-4s.

Incidentally, the CP 2-10-4 and 4-8-4 types had the same boiler. So they already had freight and passenger versions of that type.

Peter

[SD70Dude]

CN's Mountains and Northerns were also dual service engines, while CP's Hudsons were mainly used in passenger service.  

CP's ten-coupled power was designed for their mainline's steep mountain grades, and most of their Decapods, Santa Fes, and all the Selkirks spent most of their service lives out there.  

CP also really liked trailing truck boosters, while CN was not that fond of them.  Hudsons are pretty gutless at starting heavy trains without them.

[daveklepper]

Other comparisons are appropriate.  New York Centrasl had Hudsons and Niagras; PRR no steam 4-6-4s or 4-8-4s (unless you count the T1 as a 4-8-4. which it is not.).  SP and UP had lots of modern arfticulateds of several types, but AT&SF none.  But AT&SH had a fleet of 2-10-4, and UP and SP none. 

 

[M636C]

But don't underestimate the influence of the track.

It wasn't just in 1920 (or 1927 when the first 4-8-4 was named "Confederation") that the track drove locomotive designs. At the Centennial in 1967 the MLW-Dofasco truck design used on C630M, M630 and M636 types (and a few GEs after that) was designed specifically to reduce curve forces in curves and this was done at CN's request.

Take 1939... While the Royal Train was worked all the way to the West Coast by a single Hudson on CP, the train was worked back largely by Mountain types as far as Toronto, because 4-8-4s didn't generally work in the West. While the CN Mountain and Northern types had the same size driving wheels and looked very similar, the 4-8-4s were heavier and restricted to less of the system. CN 6400 did a lot less work on the Royal Train than did CP 2850 since it was confined to operating in the East.

Peter

[SD70Dude]

You are correct, track conditions were the major factor in CN's choice.  They just weren't the only one, and CP's better track did not mean that a Mountain or Northern could not have performed the Hudsons' tasks equally well.  

I have seen photos (in books, not online) of CN's Northerns working the mainline between Winnipeg and Edmonton, but they were indeed rare out west.   

[daveklepper]

Did CP's Notherns have boosters?

[Jones1945]

Canadian Pacific 4-8-4 Locomotives 

https://www.steamlocomotive.com/locobase.php?country=Canada&wheel=4-8-4&railroad=cpr#244

Source: https://www.railarchive.net/randomsteam/cpr3100.htm

Source: http://www.trainweb.org/oldtimetrains/photos/cpr_steam/3100.htm

 

[daveklepper]

Since only one fiugure is given for tractive-effort, and the is no mention of a booster, I assume there was none.

[Overmod]

Watch them building them here (turn your sound down!):

https://www.youtube.com/watch?time_continue=19&v=NcbTXlMSCwk&feature=emb_logo

Boosters mainly filled in 'one extra driving axle' when starting trains.  This implied the locomotive could, in fact, pull the train it had started once underway.  In the days of plain bearings, the vast increase in starting friction (a factor often not discussed explicitly with respect to boosters) made the ability to add TE up to about 5mph significant.  (This effect was specifically discussed in Dave Stephenson's analysis of the PRR T1 testing on C&O in the late '40s)

There were nominal advantages to being able to utilize a booster in faster service, and many of the later ones were qualified to run at up to about 32mph before disengaging.  But in the absence of effective cutoff on an engine that small, the additional steam usage (or, really, wastage) was colossal even approaching that range.  These are reasons engines like the Niagara were not designed with boosters, and why engines that verged on needing them, like the T1s, were produced without them even though one of the test locomotives was equipped.

CP would have flogged the hell out of boosters where they needed ten-coupled TE, and not have use for them many other places at the speeds necessarily involved at grade with the longer trains a booster might have been able to start.

[daveklepper]

Another point that should be made on this thread is that CP's Selkirks were definitely dual-service locos, unlike the other 2-10-4s that were primarily freight power.  The Selkirks were the regolar power for the Dominion in the mountains.