by Wiltssignal » Fri Jan 6, 2017 11:33 am
John - I had already posted a previous request in the "S&T Department" section (see "Control Tables - help Wanted") with no response, which is why I decided to try again in the "Heritage" section.
I have a background knowledge of mechanical locking and practical experience with Western Region frames (tappet and stud), Southern Region (Stevens and Westinghouse tappet) and LNWR tumbler frames, I am looking for any and all information I can get regarding Midland 6" tappet frame so that I can prepare a proposal for a new installation. I appreciate that the use of point machines (or more likely it will be clamp locks) and colour light signals relate to the electrical controls, but I would also like to know how the general mechanical locking is arranged on a Midland frame.
Hence my request for mechanical and electric control tables, locking charts and anything else which would be useful.
Examples;
Is it 4-bar or 5-bar locking? I believe the later 1943 LMS 6" frames were 5-bar locking whereas the Midland 6" frames were 4-bar locking.
How is the locking drawn on the locking chart? I know from experience that the way to draw a WR tappet locking is different to how a Stevens or Westinghouse tappet locking.
Do Midland frames use shelf plungers or catch handle contacts to activate the lever locks? I understand the frame to be used was originally fitted with "Northampton Locks" which are horizontally mounted under the operating floor. This method will be reproduced. I have worked on these locks when fitted to LNWR tumbler frames where a catch handle contact is used to pick the lock. Are catch handle contacts used on Midland frames?
Is it normal practice on a Midland frame to use a back lock (B)L on the signal lever in place of approach locking for power operated points?
The ideal would be to obtain a set of drawings for a site which has a mixture of semaphore and colour light signals, mechanical points with track locked FPLs and a point machine. Maybe a lot to ask for but any information what so ever is welcome.