I am interested in interlockings, and I have had a series of discussions on the “British Modeling” thread and elsewhere with like-minded individuals, principally Dave-the-Train. I’m in the process of designing an interlocking for my layout, and hope to get the diagram and logic posted for everyone to see and enjoy when I get some time (and finish them).
I have also found an excellent book on mechanical interlocking on Google Books that I wanted to share. This was originally published in the UK, so a lot of the stuff in it is UK-specific, but there is plenty of interesting and generally applicable stuff for anyone who’s interested in learning about interlocking; it’s a free PDF download.
And I’m still trying to figure out which American railroads used an “absolute block” system of manual control at the turn of the century - my money’s on the Reading and the Pennsy, but I haven’t found many details about practice yet.
http://books.google.com/books?id=OhmpcYF_MsAC&pg=PR5&dq=mechanical+railway+signalling#PPR2-IA3,M1
Down load this book, it is GREAT!
I’ve had a hard copy for years. Great to find on line!
http://books.google.com/books?id=BB7yLEFxpM0C&dq=mechanical+railway+signalling
Also, thanks for the link you posted.
MR’s book on junctions also has some material on modeling mechanical interlocking machines. But watch out, some of the DOG sheets contain errors. When you build something and end up with extra pieces, it is a BAD sign.
Have fun
Other links you might want to look at
http://www.du.edu/~etuttle/rail/lock.htm#Intr
http://en.wikipedia.org/wiki/Interlocking
http://modratec.com/
Note - the above company does NOT surport “when” dogs.
That’s great stuff!
I have to agree - the guide to junctions is good as far as it goes, but for any logic beyond the simplest, it’s bare-bones.
Incidentally, here’s one that someone else recommended that has some great-looking interlocking frames:
http://www.modelsignals.com/sm_parts_frame.htm
Their 7-lever frames are a work of art.
Some notes on mechanical interlocking - locking sheets
To understand the use of locking sheets in designing mechanical interlocking machines, one must understand the basic building blocks of such machines.
Given two adjacent tippets that are to be interlocked;
- 1) The first lever listed on the sheet will have a notch in it’s right side in it’s normal position and no notch in it’s right side in the it’s reversed position. Reversing the lever forces any locking dog located between the tippets to move to the right. The locking sheet specifies the LOCKING that is to when this lever is moved to it’s REVERSED position.
- 2) The second lever can have three states
- A) A notch in it’s left side in the normal position and no notch in it’s reversed position. In this case the first lever is said to lock the second lever normal.
- B) No notch in it’s normal position and a notch in it’s reversed direction. In this case the first lever is said to lock the second lever reversed.
- C) A notch in both positions. In this case the first lever is said to lock the second lever normal and reversed.
The locking sheet entries would be;
|
Case
|
Reversing lever
|
Locks
|
|
A
|
1
|
2
|
|
A*
|
There is a Yahoo group dedicated to interlockings and towers. I’m not a member but it should be fairly easy to find and register to be a member. It’s free of course but you may need to create a Yahoo user name (also free).
I’ll have to check it out. I’ve been laboring through the design of the interlocking plant, which is a bit more complicated than I had planned, natch, but at some point I’m going to download the free software and try that out.
The Old Dog would strongly suggest that you down load the book whose link I posted above. It will answer many of your questions.
Have fun
I did, and I appreciate it. I’m finding that a lot of the best resources for interlocking are foreign; it’s apparently something of a niche interest here in the States. I picked up a couple of books that MSE puts out on building British signals; the actual designs are all foreign, but the mechanics and detailing suggestions are useful and first rate.
1st) Let’s double check the title, the book the Old Dog has is Railway Signaling, Theory and Practice, 1909, by James Brandt Latimer.
2nd) Please note that Mr Latimer was a Signal Engineer for the Chicago, Burlington & Quincy Railroad, hence he reflects US practice.
3rd) Your reading assignment, Chapter III Interlocking - Mechanical and Chapter XVI Locking and Dog Sheets. Those two chapters contain the most interesting material which is not to say that some of the other chapters are not also interesting.
Have fun