4-8-4 - Frame, Axle And Rod Bearings, Performance On Grades, Adhesion Factor, Reputation - Inquiry

Discussion in '4-8-4 Northern' started by loganistrainboy1, Feb 8, 2015.

  1. I find it interesting how little information about these locomotives is readily available, given four survive and they were so well known on the Frisco.

    I have a few questions.

    Given that 4500-4502 were passenger locomotives built in 1942, I would assume that the 4500s were built with a one piece cast frame and cylinders.

    Can anyone confirm?

    Does anyone know if the 4500s had roller bearings on the driving axles?

    Most modern passenger power did even if they had friction bearing rods.

    I have heard very little about how well the 4500s did on the Frisco. I read something saying that they were "prairie engines". That is a very vague description. "Prairie engine" would likely mean they would not have done well with grades. I am not familiar enough with the Frisco to know what kind of grades would have been encountered.

    Does anyone know if the crews liked the 4500s and how they compared to other Frisco power?

    They did not have front end throttles and had a very high tractive effort compared to the weight on drivers, which in theory would have made them slippery. But, I have not been able to find any stories on how they actually performed in service.

    I have also wondered why the Frisco was so partial to Baldwin but maybe that is a question for another thread.

    Any help answering these questions would be appreciated!

    Logan Schupp
    Last edited by a moderator: Mar 15, 2024
  2. Karl

    Karl 2008 Engineer of the Year Frisco.org Supporter

    1.) The 4500s had a one-piece cast frame and steam chest.

    2.) The 4500s had friction bearings on the wheels and the rods.

    3.) Since they were a high horsepower locomotive, they needed to be rolling above about 45 mph to produce all of their designed horsepower. Working up-hill at lower speeds, they were not as efficient as a 4-8-2 4200, for example.

    http://ctr.trains.com/~/media/Files/PDF/4-8-4 Locomotives/5-Later Baldwin 4-8-4 DBHP.pdf

    4.) Don Wirth can answer this one.

    5.) They had a factor of adhesion (FA) of about 3.94. A FA of 4 is good, anything greater than four is better, and anything appreciably lower than 4 was slippery.

    For example the Bolsheviks had a FA of 3.59. They were slippery coming out of the sand house.

    Attached Files:

    Last edited by a moderator: Mar 15, 2024
  3. Thanks for the response, clears up a lot of questions.

    Last edited by a moderator: Mar 15, 2024

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