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MoS/WD 0-6-0T (LNER J94 type) valve setting.

Discussion in 'Locomotive Engineering M.I.C' started by Eightpot, Dec 8, 2014.

  1. Eightpot

    Eightpot Resident of Nat Pres Friend

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    Is there any published material on setting the cylinder slide valves available?
     
  2. John Webb

    John Webb Member

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    There is a lot of information on valve-gear setting in D W Hardy's book "A Manual of Steam Locomotive Restoration and Preservation" (David and Charles, 1980) which may be of use, although it is in general terms, not specific to any particular locomotive.
     
  3. Steve

    Steve Resident of Nat Pres Friend

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    Assuming that you are not talking about position of eccentrics on the axle etc, for a slide valve loco you want to be setting the valves for equal port openings. You might wish to make an allowance for temperature/expansion if setting it cold.
     
  4. Eightpot

    Eightpot Resident of Nat Pres Friend

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    Yes, Steve, it is for setting the port openings. Have removed the front cover cum valve spindle guides but can only see that end of the cylinder assembly. Will it be necessary to remove valves to measure them and the port faces, or is there a simpler way?
     
  5. John Webb

    John Webb Member

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    D W Harvey's book says that if you do not know the amount of lap, it is necessary to remove the slide valves, take impressions of the port openings, and then lay the slide valve on the impression to sort out the amount of lap. Once done, if kept for reference the valves will not need to be removed on future occasions. The following work to set the valves is too lengthy and detailed to be repeated here; if you can get a copy of the book, I would.
     
  6. Steve

    Steve Resident of Nat Pres Friend

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    If you can get a hand and arm between the valves, you shouldn't need to remove them. If not, you will have to remove the opposite valve. You'll probably need a mirror to see what you are doing, though. If the valve travel is greater than the port opening set them up for equal port opening with it notched up a bit. You can use suitable wooden wedges to measure the rear port opening. Push a suitable clean wooden wedge into the port and it will leave a mark on the wood, which you can then measure to get the opening. Make sure that the end of the wedge doesn't 'bottom' and that you get it perpendicular to the valve face. The problem with it not being in full gear is that it makes adjusting the eccentric rods a bit more of a guess.
    As you suggest, you can remove the valves and carefully measure all the relevant dimensions and then just work off the front port. I would expect an Austerity to have valves and ports properly machined to drawing dimensions but the Victorians weren't always too bothered about such niceties!
    Probably teaching you to suck eggs but it is important that you only move the loco in the direction that you are setting the valves for to eliminate any motion errors. If you run out of space and have to go back, the loco needs to be moved sufficiently in the correct direction to eliminate errors before any measurements are taken. Another thing to take note of is that the relationship between the reversing lever and expansion links is correct, although this will not affect actual valve setting.
     
  7. Steve

    Steve Resident of Nat Pres Friend

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    My 'bible' on valve gears is 'Valves & Valve gears for Steam Locomotives' by Lake & Reidinger. A reprint of this can be got from Camden Miniature Services and Christmas is coming. 'Locomotive Valves & Valve Gears' by Yoder & Wharen also has a lot on valve setting and an imprint of the 1921 edition was again done by Camden but I don't think this is in print any more. You can pick up a used copy, though.
     
  8. Eightpot

    Eightpot Resident of Nat Pres Friend

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    No room between the valves so it rather looks as if we will have to have them out and do some measuring first.
     
  9. Steve

    Steve Resident of Nat Pres Friend

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    Have you tried Statfold Barn for a drawing?
     

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