What are all the different style of steam crossheads?

RCB Jun 21, 2012

  1. RCB

    RCB TrainBoard Member

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    I am familiar with the Laird and Alligator. How many different styles have there been on steam locomotives?
     
  2. COverton

    COverton TrainBoard Member

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    I am only aware of the two, single guide and dual guide, Laird and Alligator. The looks differ, and perhaps their sliding mechanics, but the general configurations are pretty much only the two that I know.
     
  3. fitz

    fitz TrainBoard Member

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    I always referred to non-alligator crossheads as Laird, but have also seen them referred to as "multiple bearing" crossheads (I think). If I can find pix I will post them.
    :teeth:
     
  4. Mike Sheridan

    Mike Sheridan TrainBoard Member

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    The only other type (aside from single and dual guide) is the cylindrical, but I've never seen that on a loco, only stationary or marine engines.
    But as Crandell says there are a lot of detail variations with those general types.
     
  5. fitz

    fitz TrainBoard Member

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    Here's a good shot of an Alligator crosshead on CP Hudson 2816.

    [​IMG]

    And a Laird, or Multiple Bearing Crosshead on SP&S 700

    [​IMG]
     
    Last edited by a moderator: Jun 23, 2012
  6. Hytec

    Hytec TrainBoard Member

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    And another Laird.....

    [​IMG]
     
  7. fitz

    fitz TrainBoard Member

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    Hank, great photo. Without trying to turn this thread into a New York Central discussion, I have to present this photo of a New York Central Hudson. The Central was BIG on Alligator crossheads, and most passenger locomotives had them. The Niagara was a departure from the norm, but a great engine.

    [​IMG]
    J-1 5229, from the collection of Harold K. Vollrath, my copy.
     
  8. Shortround

    Shortround TrainBoard Member

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    Sorry for breaking in guys but, could someone help me understand what is being discussed. I'm interested but not up on terminology of steam engines.
    Thanks.
     
  9. Hytec

    Hytec TrainBoard Member

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    I think this Wiki description should help you....http://en.wikipedia.org/wiki/Crosshead. Though please ask further for more details or clarification.
     
  10. fitz

    fitz TrainBoard Member

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    Take a look at the hardware in each of those photos that is directly behind the piston housings on the locomotives. The crosshead holds the piston shaft in place and controls its motion to strictly fore and aft, parallel to the ground. The main drive rod which imparts that fore and aft motion as the piston runs fore and aft into the circular motion of the drive wheels is attached to a sliding mechanism held by the crosshead. The "alligator" crosshead has horizontal structural members both above and below that sliding mechanism, whereas the Laird or multiple bearing crosshead has only one, above the slider. Hope this helps.

    :wideeyes:
     
  11. Mike Sheridan

    Mike Sheridan TrainBoard Member

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    Minor nitpick: Strictly speaking (and the diagram in the Wikipedia link does show it) what we are talking about above are the crosshead guides. I understand the crosshead is actually the sliding part at the joint between the piston rod and connecting rod - possibly named because (particularly on some alligator styles) it takes something of the form of a cross (but I'm prepared to be wrong on that bit :) ).
     
  12. COverton

    COverton TrainBoard Member

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    Correct, and that is why I used the term in my response on the first page. :happy:
     
  13. fitz

    fitz TrainBoard Member

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    You are absolutely right. I could not get the correct terminology out of my ancient brain. Guides. It would have helped if I re-read your original, Crandell.

    :oops:
     
  14. RCB

    RCB TrainBoard Member

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    Thanks, I've notice some difference between different Laird/Multiple Bearing types.

    Thanks for all the responses!
     

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