If you register, you can do a lot more. And become an active part of our growing community. You'll have access to hidden forums, and enjoy the ability of replying and starting conversations.

7027 Thornbury Castle

Discussion in 'Steam Traction' started by svrhunt, Jan 18, 2015.

  1. ross

    ross Well-Known Member

    Joined:
    May 18, 2017
    Messages:
    801
    Likes Received:
    1,893
    Gender:
    Male
    Location:
    Titfield
    Heritage Railway Volunteer:
    No I do not currently volunteer
    Poor old Thornbury. Thank heavens she now has an owner who isn't full of waffle, or good intentions. These regular updates are a joy.
     
  2. Richard Roper

    Richard Roper Member

    Joined:
    May 22, 2006
    Messages:
    1,040
    Likes Received:
    916
    Gender:
    Male
    Occupation:
    Librarian
    Location:
    Just up the road from 56E Sowerby Bridge
    Heritage Railway Volunteer:
    No I do not currently volunteer
    I have to say, being an ignoramus on things Great Western, that frame looks rather flimsy to my eye. It obviously did the job, but doesn't look half as substantial as a plate frame bogie... Or has it been stripped down?

    Richard.
     
  3. Flying Phil

    Flying Phil Well-Known Member

    Joined:
    Dec 10, 2018
    Messages:
    1,355
    Likes Received:
    2,334
    Gender:
    Male
    Location:
    Leicestershire
    Heritage Railway Volunteer:
    Yes I am an active volunteer
    Hi Richard
    I think it is stripped right down. There are lots of bolts showing where other brackets/castings are to be attached - which will make it a far more substantial affair!
     
    Richard Roper likes this.
  4. Flying Phil

    Flying Phil Well-Known Member

    Joined:
    Dec 10, 2018
    Messages:
    1,355
    Likes Received:
    2,334
    Gender:
    Male
    Location:
    Leicestershire
    Heritage Railway Volunteer:
    Yes I am an active volunteer
    Just a quick "heads up" that "Thornbury" was mentioned at the GCR AGM as being steadily progressed (along with 70013 and the 04).
     
  5. huochemi

    huochemi Well-Known Member Friend

    Joined:
    May 6, 2008
    Messages:
    2,467
    Likes Received:
    1,188
    Gender:
    Male
    Location:
    UK
    Thanks for the image. This bar frame style of bogie which was introduced in the USA, is flimsy but the bogie frame does not have to do much other than provide horizontal guidance and the bars are quite sturdy in that direction. The frame does not transmit the loco weight or any braking or acceleration loads. The missing bits (wheelsets, springs, equalising beams etc) do not add to the rigidity. Although Stanier took the design to the LMS (Princess, Duchess), the LMS modified the design to use plate frames for the 4-6-0 classes, later used on BR Standards. There seem to be practical problems with the original design, not least that one has to take off the whole of the bottom frame to remove the wheelsets, and I suspect the flimsiness of the dismantled frame enabled the horns to spring and an oversized axlebox to be inserted into 46207's bogie which caused its derailment at Weedon.

    The function of the bogie design is described in the Weedon accident report:
    8. The weight of the engine at the front end is transmitted to the bogie centre casting by heavy cast steel brackets bolted to the main frames at each side. A hemispherical projection on the underside of each bracket is seated in a cast iron cup with a plane under-surface, which slides, in accordance with the lateral displacement of the bogie, on an oil-lubricated gunmetal alloy pad on the bogie centre casting. As shown by Fig. 8, there is a socket at each side of the centre casting which bears directly on a spigot formed integrally with the buckle of the laminated spring, and the weight on the spring is transferred to the axle boxes by the twin compensating beams which are linked to it. The comparatively light bar frames of the bogie, of which the long horn stays form the lower members, thus carry no weight and serve only to locate the axles longitudinally and laterally. Nor is any weight carried by the central bogie pivot. Side control is by coil springs acting with an initial centring force of 4 tons, rising to 5 tons at the maximum displacement to one side of 2 7/8 ins.
     
    ross and Richard Roper like this.
  6. Flying Phil

    Flying Phil Well-Known Member

    Joined:
    Dec 10, 2018
    Messages:
    1,355
    Likes Received:
    2,334
    Gender:
    Male
    Location:
    Leicestershire
    Heritage Railway Volunteer:
    Yes I am an active volunteer
    I saw that more progress has been made on 7027, as the crank axle has been painted and the axle box hornguides have been dimensioned, presumably for machining the axleboxes? Unfortunately I was unable to get a picture.
     
    Johnme101 and ross like this.
  7. Matt37401

    Matt37401 Part of the furniture

    Joined:
    Jun 8, 2014
    Messages:
    10,483
    Likes Received:
    6,109
    Gender:
    Male
    Occupation:
    Never you mind
    Location:
    31A
    Heritage Railway Volunteer:
    No I do not currently volunteer
    Things are (or getting ready to be moved) moving ;)
    Cinders, at long last you shall come to the ball!
     
    Richard Roper likes this.

Share This Page