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BR Standard class 6 No. 72010 'Hengist' and Clan Discussion Thread

Discussion in 'Steam Traction' started by Bulleid Pacific, Nov 23, 2009.

  1. ianh1

    ianh1 New Member

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    No, all of these bolts are right hand (normal) threads. The original design of the main piston head and piston rod used a combination of a right hand thread nut and a left hand thread nut (LH with a smaller diameter) to lock the nuts onto the piston. This had problems as reported in Bill Harvey's book "60 Years in Steam" in which he says "Three cases of Piston Head L.H.' check nuts breaking off have occurred. (Later engines have LNE type head forged solid with rod)." The CLIP report recommends the latter design

    In addition to this locking arrangement, there are a few places where LH threads are used, for example on the Brake adjusting Pull Rods & Nuts
     
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  2. northernsteam

    northernsteam New Member

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    Yep, that's it! except in my day there were no programmers so that was the design from the engineer.
    O happy days:D
    Thanks to ianh for pointing out my error, I did know that, just forgot. This really can be a minefield of alternatives and ideas. Most of which have been used over the last several decades in 1 form or another, who said something about inventing a wheel? (never catch on :Resistanceisfutile:).
     
  3. std tank

    std tank Member

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    The fitting of LNER type piston heads/rods was an experiment carried out on Brits 70035-70044 . The units were fitted during 1952/3 and removed in 1957, with conventional heads and rods being refitted, as well as new front cylinder covers. 71000 was also fitted with the same design of piston heads/rods and forgotten about. Only now is it being fitted with conventional pistons, piston rods and front cylinder covers.
     
  4. class8mikado

    class8mikado Member

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  5. Hermod

    Hermod New Member

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    What was wrong with the LNER forged head scheme and do You have a picture or drawing?
     
  6. std tank

    std tank Member

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    Don't know why they were thrown out. The Duke people reckon there was excessive wear on the cylinder bores. Yes, there are drawings. By the way, the drawing for the piston and rod used in the experiment on the ten Brits shows a machined cast piston head butt welded on to a , presumably, forged and machined piston rod. Obviously, the entire piston and rod would be finish machined after welding.
     
  7. Steve

    Steve Part of the furniture Friend

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    They are an expensive option when you need to renew them, which is often necessary when you machine the cylinder bores.
     
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  8. ilvaporista

    ilvaporista Well-Known Member

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    Recently on a build thread of a 5" Flying Scotsman on the MECH forum there was a discussion and drawing of the integral forged head and piston rod, including the hollow rod. I have tried to find it but got bogged down reading so many other posts that I feel asleep. Maybe Julian jma1009 has a better memory and searching solution than me.
     
    Last edited: Oct 24, 2019
  9. class8mikado

    class8mikado Member

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    Which seems to happen a little too frequently with Standards.
    We await with interest how steps to improve matters on DoG progress. the thing with changing lots of small things to solve a problem is pinning the tail on the right one if the problem is solved,,,, ( Lubrication, slide bar anchoring, piston design...)
     
  10. ianh1

    ianh1 New Member

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    We had a good day out on the East Lancs Railway. Anthony Pilkington is the assembly shop supervisor at CTL Seal and he is responsible for the daya to day building of Hengist. We were very keen to get a footplate experience for Anthony so John Hind kindly set up a trip for Anthony. So yesterday morning we had a trip from Bury to Rawtenstall. On the return, Anthony travelled on the footplate from Rawtenstall to Ramsbottom; Keith Greenhow (our CAD modelling expert) travelled from Ramsbottom to Bury. Both wonderered why the loco didn't have any springs!

    In the afternoon we went round Bury works and had a very useful conversation with Dave Reynolds of the ELR. Dave was in the process of aligning a LMS Crab 2-6-0 and was able to pass on a lot of useful information about alignment of frames. Many thanks to John and Dave
     
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  11. ilvaporista

    ilvaporista Well-Known Member

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    Not sure if this works.
    http://redirect.viglink.com/?format...3_954eb64900_c.jpg" style="max-width: 100%;">
     
  12. Hermod

    Hermod New Member

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    Thank You for picture/drawing
    The thing was forged,stress relieved,machined,sent to foundry and got a bronce crown cast on as ring carrier and then machined to final size.
    No wonder that BR did not like this former LNER way.
    On the other hand mr Cox measured his own ability on superheat temperature.
    Mr Chapelon claimed that a sligth reduction in superheat temperature could be counteracted by a sligthly better boiler evaporation and cylinders would last longer with lower superheat.
     
  13. 'Clan' Hengist

    'Clan' Hengist New Member

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    Latest news from the 'front line'... Centre Slide Casting.jpg

    The bogie centre slide has been cast. After heat treatment/stress relief, and completion of all pre-delivery checks, this will be forwarded to CTL for machining in the near future. Great to be able to finish the year with such positive news.
     
  14. W.Williams

    W.Williams Well-Known Member

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    This is good.
     
    Last edited: Feb 18, 2020
  15. 242A1

    242A1 Member

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    The design of the pistons on the early LNER Pacifics was the subject of a number of experimental developments and it was in 1932 that a satisfactory arrangement was arrived at

    At first the pistons and rods were forged from nickel chrome steel with the rods being hollow to deliver a reduction in both weight and inertia. To reduce wear on the cylinder wall the pistons had a bronze rim cast on to them and the piston rings were 3/4" wide cast iron type spaced 3/8" apart.

    Trials were being made with 5/8" wide piston rings on selected 4-4-0 types and following satisfactory reports being received an order was given on 30th Jan. 1926 for two Pacifics to be trial fitted. The engines selected were 2547 which was fitted in the March and 4479 which was fitted in June. 2547 failed while working a London bound express on 22nd of July, details of the exact cause are not available. The decision for a trial fitting of a renewable cast iron rim secured by means of rivets to the piston head does support conclusion that the bronze rim had become detached. Locomotive 2558 was fitted with the cast ion rims in November 1926.

    From September 1927 mild steel replaced nickel chrome steel on the piston and rod forgings and the fitting of a separate rim was ended, for a while at least.

    Gresley advised Doncaster of his intention to carry out an experiment on an A3 class. This was on 7th July 1928 and required the right hand and centre cylinders to be fitted with mild steel rather than cast iron liners. The pistons were to be given a 1/16" electro-plated nickel rim with super nickel rings on the r.h. piston and conventional cast iron on the centre. Engine number 2752 was selected and was the last of a batch of A3s coming out April 1929. This experiment was carried out with the aim of finding out if cylinder wear could be significantly reduced or not.

    In January 1929 the decision was made to leave all new piston rods solid.

    In July 1929 it was decided to experiment with a renewable bronze rim on a mild steel piston head again secured by means of rivets and fitted with narrow rings. 4472 was fitted on the left and centre cylinders and 2562 was fitted on the right-hand. On 19th June 1930 it was reported by the Running Department that over half the rivets on 4472's piston heads had worked loose with the result that the experiment was abandoned and ordinary pistons reverted to.

    In order to address the problem of excessive cylinder wear it was decided to bore out the cylinder castings and to fit cast iron liners which in 1931 standardised on boring the castings out to 21" and fitting an A1 liner or an A3 liner as required.

    There were experiments with alternative piston ring materials in 1932 but these were short lived.


    I once again acknowledge and give thanks again to the RCTS and volume 2A.

    The LNER were wanting to avoid a piston and rod becoming detached at high speed and if you think that this should not be a concern or imagine that the head and rod cannot work loose then have a look through the pages of The Red Devil, even so late in the course of steam development it happened.

    So the LNER did experiment with the addition of bronze piston head rims but these were found to be unsatisfactory. So the question is, why model them when they are not going to either work or be seen? I would also add that there has been many an opportunity to view LNER Pacifics stripped for overhaul in the NRM workshops over many years, viewing the items in question has been rather easy.
     
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  16. ianh1

    ianh1 New Member

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  17. northernsteam

    northernsteam New Member

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    Excellent to see the volunteers hands on in the assembly, again. It shows a good relationship with CTL Seal.
    Well done to all involved in the project progress.
     
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  18. ianh1

    ianh1 New Member

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    Unfortunately, due to the current virus situation, we will have to cancel our planned Open Day on the 18 April. We will reschedule as soon as things return to normal

    Ian
     
  19. jnc

    jnc Well-Known Member

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    Reading the latest items on the Latest News page, I'm struck by the job that CTL Seal is doing. They were an excellent choice by the project!

    Noel
     
  20. ianh1

    ianh1 New Member

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    Hi Noel

    Thanks for that. CTL Seal's staff are very enthusiastic about the project and we are working very well with them. There can't be many loco groups working in a nice big (relatively warm!) assembly shop!

    Ian
     
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