Early diesels and tracks

I thought that diesels were generally much easier on track than steam engines, which suffered from dynamic augment as a result of unbalanced reciprocating masses.

Personally, I agree with B Smith, as to diesel-electric locomotive trucks.  Diesels normally tolerate bad track better than rigid-frame steam engines.

Some diesel truck designs were inclined to ride roughly, and the brake rigging on some was difficult to keep in adjustment (Examples: Alco Blunt switcher truck, and early Alco tri-mount 6 wheel trucks with a single brake cylinder per side).

Santa Fe had trouble with the EMD Blomberg truck on its F-units in passenger service at first.  Conceived to be a freight service truck, it had high speed hunting problems, until Santa Fe applied flat taper wheels, after which the tracking qualities were quite satisfactory at 100 MPH.

The question is valid and the problem did exist, but apparently no one here knows the answer so far.  Every bit of knowledge is not online, I read about this issue maybe 50 years ago, and thought maybe someone else remembered it.  The story was quite clear that one particular truck style was known for pushing track out of gauge, that is not something you forget if you read about this stuff.

@CALNNC posted:

The question is valid and the problem did exist, but apparently no one here knows the answer so far.  Every bit of knowledge is not online, I read about this issue maybe 50 years ago, and thought maybe someone else remembered it.  The story was quite clear that one particular truck style was known for pushing track out of gauge, that is not something you forget if you read about this stuff.

Well sir, I've been in the diesel electric locomotive business since 1962, ( isn't that about 60 plus years?), and can tell you from experience that no mater what you read or heard, it wasn't/isn't true.

The N&W had to restrict ALCO 628 units to 35mph because of the trucks damaging track.

It would seem that in order to actually push rails out of gauge there would have to be very serious problems with hunting at relatively high speeds in order to create high enough lateral forces to cause that kind of damage. I don't remember reading any references to this problem with any particular diesel trucks, but it would be interesting to learn more from comparative technical reports. For example,  I the PRR conducted and published the results of tests conducted in the 1930s to compare the effects on track of electrics versus steam engines (K-4s?), and the electrics were shown to cause significantly less stress to the track structure. There's probably some data like this available for a diesel/steam comparison with different truck-types, etc. Just have to find it ...

Are you thinking of the saga with the SDP40Fs by chance? Those had trucks that were blamed for breaking rails, though it seems to not have been the trucks' issue.

@RootBeerRail posted:

Are you thinking of the saga with the SDP40Fs by chance? Those had trucks that were blamed for breaking rails, though it seems to not have been the trucks' issue.

Correct, i.e. NOT the trucks but, the overall weight of the SDP40F when all the boiler water supply tanks were full, and then operated over crappy track. Gee, no wonder they derailed!

Referring back to the original post, and the subject title, by "early diesels" when compared to main line steam locomotives of the 1940s, 1950s and early 1960s, the axle loadings on the "early diesels" was much, MUCH lower than the axle loadings of most main line steam locomotives.

I'll say one last thing, and that is that some things get put into print without being totally accurate.

We can trust a quotation from an authoritative person with first hand knowledge of a fact which being reported, but, especially in railfan publications, there is -- in addition to factual information -- a lot of hearsay.  We have to be skeptics in some cases, especially when the source is not clear.

So far nothing here has enlightened the original post except Big Jim (a retired N&W Engineer) reporting that N&W restricted its C628 locomotives to 35 MPH, but it is not clear whether that was on all lines or just certain territories, and whether it was permanent or temporary until modifications could be made, and also whether the restriction was when the locomotives were new.  The cause would interesting to know.  N&W technical society might have something.  Since no reports of other railroads restricting their 628's similarly have come in, more on the specific situation on N&W would be interesting.

The only information I have read over the years relates to the lateral stresses that PRR P5as and the R1 placed on the rails at higher speeds compared to the GG1 which is why the GG1 was selected to be built as PRR's mainline electric passenger locomotive.

The SDP40F was certainly not an early diesel and the various reasons for its derailments have been documented thoroughly over the years even if it took a long time to pin it down the issues to the amount of weight in the water tanks, the quality of the track they ran on, and the weight differential with the lightweight baggage cars that followed.  It should be noted that the SDP40F served the ATSF well in freight service with the units they purchased 2nd hand from Amtrak. 

I have not heard of issue with early diesels.  A reciprocating machine puts a lot of stress on the rails, and I experienced that first hand in 2011 when the UP 844 passed me at 60 mph and the ground shook beneath me in a way I have never experienced with a diesel at similar speeds.

It was the ALCO C628 where I first read about its effects on track structure, and the Monon discontinued their use because of this.  After looking though several books I have and online, found an article on the 628 talking about its effects on track.  Perhaps today with concrete ties, welded rail, and much more secure attachment, it would not be an issue, but apparently, jointed rail spiked to wood was not a C628's friend.

@CALNNC posted:

It was the ALCO C628 where I first read about its effects on track structure, and the Monon discontinued their use because of this.  After looking though several books I have and online, found an article on the 628 talking about its effects on track.  Perhaps today with concrete ties, welded rail, and much more secure attachment, it would not be an issue, but apparently, jointed rail spiked to wood was not a C628's friend.

Except,,,,,,,,,,,,an "ALCO C628" is NOT an "early diesel", i.e. 1930s, 1940s, and/or 1950s.