Search found 195 matches

by andrew jukes
Sat Mar 15, 2014 9:47 pm
Forum: Lathe Work
Topic: Sick Unimat
Replies: 28
Views: 12103

Re: Sick Unimat

I have followed this list: unimat3@yahoogroups.com for some time and the subject of failing Unimat 3 motors has come up often. The most strongly recommended solution has been to replace the motor with a 24V DC motor and appropriate power supply. Here is an example from 2011: "My poor little Uni...
by andrew jukes
Thu Mar 06, 2014 5:59 pm
Forum: Track and Turnouts
Topic: Track construction - a reflective moment
Replies: 17
Views: 3735

Re: Track construction - a reflective moment

But we be might be slightly at cross purposes here as you seem to be talking about track panels, (as was Mark above) whereas John was talking about a tandem turnout. I was using 'panel' a little loosely. I think of any chunk of pre-assembled track - including P&C - as a panel - as in this old p...
by andrew jukes
Thu Mar 06, 2014 10:50 am
Forum: Track and Turnouts
Topic: Track construction - a reflective moment
Replies: 17
Views: 3735

Re: Track construction - a reflective moment

Time perhaps to try the hybrid approach of soldered construction where rigidity is essential, chairs elsewhere.....This is a good thread : stimulating...... I have never understood the enthusiasm for 'hybrid' construction. One of the big improvements track built with functional plastic chairs bring...
by andrew jukes
Sun Jul 14, 2013 12:02 pm
Forum: Baseboards and Carpentry
Topic: P4 in the garden - has it been done? Is it practical?
Replies: 25
Views: 7292

Re: P4 in the garden - has it been done? Is it practical?

Tim said - Suggest avoid sharp curves - puts track under tension to straighten out. Put track on floating base inside box. and I disagree on both points. Obviously make curves as large radius as you can but track only wants to straighten out if the rail is not curved to the desired radius before ass...
by andrew jukes
Tue Jul 02, 2013 10:21 pm
Forum: Semaphore Signals
Topic: Double Block Working
Replies: 29
Views: 11804

Re: Double Block Working

Glad I didn’t imagine the poorer braking performance of lighter trains! Here’s another wrinkle that double block working has to accommodate - I have just about got clear in my mind that the streamliner would get two distants at caution before encountering a stop signal at danger and that this could ...
by andrew jukes
Sat Jun 29, 2013 12:47 pm
Forum: Semaphore Signals
Topic: Double Block Working
Replies: 29
Views: 11804

Re: Double Block Working

I think the safety justification is reinforced by the obvious concern of the LNER with the braking performance of the streamliners. There was a fair amount of development work on the trains' braking system and there were braking tests of the trains (wasn't Mallard's record run part of this?). The pr...
by andrew jukes
Sat Jun 29, 2013 9:15 am
Forum: Semaphore Signals
Topic: Double Block Working
Replies: 29
Views: 11804

Re: Double Block Working

A better way of thinking about type C (Keith’s definition) double block working may be that what it’s trying to do is shift control of every distant signal to the box one in advance. Thus, with an A - B - C sequence of boxes/blocks, box B needs block A’s distant only to be cleared when box B is able...
by andrew jukes
Fri Jun 28, 2013 2:56 pm
Forum: Semaphore Signals
Topic: Double Block Working
Replies: 29
Views: 11804

Re: Double Block Working

Thank you John for posting the enquiry. There is something missing here. I think. If it's ever possible to bring the Coronation to a properly controlled stop, using the distants of two successive blocks to reduce its speed to normal, It must be possible for the box in advance to distinguish between ...
by andrew jukes
Fri Jun 28, 2013 1:09 pm
Forum: Semaphore Signals
Topic: Double Block Working
Replies: 29
Views: 11804

Re: Double Block Working

Keith’s right, C is the case I’m interested in and it would be good to see the instructions given at the time for the streamliners. Thinking about it some more, under double block for the streamliners I would expect the first distant at caution to be followed by clear home and starter and the driver...
by andrew jukes
Thu Jun 27, 2013 6:23 pm
Forum: Semaphore Signals
Topic: Double Block Working
Replies: 29
Views: 11804

Re: Double Block Working

When I started this thread, I said I couldn’t imagine ever implementing double block working - but what I might hope to do is play out the consequences of it. I am modelling Welwyn North in 1938/9 and, if the signalling is ever installed and I have the trains to do it, I will be able to play out som...
by andrew jukes
Wed Jun 26, 2013 12:18 am
Forum: Semaphore Signals
Topic: Double Block Working
Replies: 29
Views: 11804

Re: Double Block Working

Howard You make it sound as though the ECML in 1937-39 could be emptied for the streamliners. Accepting that passenger train frequencies were far lower than today’s, there were three streamliners each way each weekday south of Doncaster averaging over 70mph and many more two track sections - and the...
by andrew jukes
Tue Jun 25, 2013 1:07 pm
Forum: Semaphore Signals
Topic: Double Block Working
Replies: 29
Views: 11804

Re: Double Block Working

It seems to me the other key point is that offer and acceptance between boxes becomes a two stage process. The first stage is an enquiry, not really an offer - Is train out of section? The second stage is the proper offer. So in the example, B is enquiring of C, not making a proper offer. If it's no...
by andrew jukes
Tue Jun 25, 2013 12:40 pm
Forum: Semaphore Signals
Topic: Double Block Working
Replies: 29
Views: 11804

Re: Double Block Working

I had wondered if it might work something like that but rejected it on the basis that it puts everyone in an ambiguous position. How can you have identical looking distant signals at caution which can have two different meanings with quite different implications for the speed through a block without...
by andrew jukes
Tue Jun 25, 2013 9:43 am
Forum: Semaphore Signals
Topic: Double Block Working
Replies: 29
Views: 11804

Double Block Working

This is not really a modelling point as I can’t ever imagine implementing it but I am curious about how double block working actually worked. I understand it was used for the LNER streamliners and I am trying to picture what it would mean from a driver’s perspective. As I understand it, double block...
by andrew jukes
Thu Jun 13, 2013 5:46 pm
Forum: Track and Turnouts
Topic: Trackbuilding questions
Replies: 12
Views: 5107

Re: Trackbuilding questions

I differ with JFS in that I have found that you can adjust chairs after they have been stuck to a plastic sleeper by re flooding with your liquid glue then sliding a scalpel balde underneath to seperate. If a chair does disintergrate, as it does on occasions, then it can easily be replaced by cutti...
by andrew jukes
Sun Apr 28, 2013 4:09 pm
Forum: Chassis and Suspensions
Topic: Flywheels
Replies: 48
Views: 15333

Re: Flywheels

Given that the space is often pretty much fixed, I think the interesting question is whether it's better to have a smaller motor and flywheel or a larger motor. My inclination is to go for the larger motor every time, but that's not based on any analysis. I'm intrigued by Keith's 'keep alive' capaci...
by andrew jukes
Mon Apr 15, 2013 6:23 pm
Forum: Coaches and NPCS
Topic: LNER Trains
Replies: 0
Views: 1605

LNER Trains

I have been discussing with Golden Age Models the details of the running gear of the P4 versions of the LNER trains they are currently producing (the Silver Jubilee, the Coronation/West Riding Limited and the 1938 Flying Scotsman). I am now fully satisfied that they are working to acceptable dimensi...
by andrew jukes
Tue Apr 09, 2013 2:15 pm
Forum: Coaches and NPCS
Topic: Width of Gresley Bogies
Replies: 9
Views: 6353

Re: Width of Gresley Bogies

Thanks for the responses. With a drawing showing 7’ 7” as the over-axlebox dimension for a BR Mk 1 bogie, I thought it unlikely a Gresley bogie would need to be wider unless the position of the primary springs made this necessary. Nobody seems to be suggesting that, so 30.33mm might be a reasonable ...
by andrew jukes
Mon Apr 08, 2013 6:49 pm
Forum: Coaches and NPCS
Topic: Width of Gresley Bogies
Replies: 9
Views: 6353

Width of Gresley Bogies

Golden Age Models are finalising their soon to be released LNER trains - Coronation, Silver Jubilee and 1938 Flying Scotsman - and I'm discussing with them the running gear for P4 versions. I think the wheelsets will be satisfactory but they are planning to widen the bogies to accommodate the P4 whe...
by andrew jukes
Thu Jan 24, 2013 5:24 pm
Forum: Track and Turnouts
Topic: Bullhead and Flat Bottom Rails
Replies: 25
Views: 13522

Re: Bullhead and Flat Bottom Rails

I think the main incentive for the initial introduction of FB rail was the maintenance cost saving arising first from the greater stiffness of the rail and - more significantly - from introducing continuously welded rail. Such savings are always likely to be greatest where traffic levels are high an...
by andrew jukes
Mon Dec 03, 2012 7:41 pm
Forum: Starting in P4
Topic: First dabble in P4
Replies: 49
Views: 15769

Re: First dabble in P4

Sorry, Tim, but that's not quite right. The P4 standards stipulate a B-to-B in the range 17.67mm - 17.75mm. The Society's recommendation is to work at the upper end of the range and I believe Scalefour Stores gauges are 17.75mm. Bernard Weller always insisted the correct P4 standard to be 17.67mm an...
by andrew jukes
Sun Dec 02, 2012 1:13 am
Forum: Layouts and Operations
Topic: 1st P4 layout - Endex
Replies: 153
Views: 50561

Re: 1st P4 layout

Knuckles The Exactoscale Tortoise Adaptor Plates will be available again in due course but you might anyway find the information in the instructions for them helpful. They give the dimensions and describe the approach I've used successfully on a fair number of turnouts. See: http://www.exactoscale.c...
by andrew jukes
Sat Dec 01, 2012 11:27 pm
Forum: Track and Turnouts
Topic: Turnout Chairs
Replies: 6
Views: 3220

Re: Turnout Chairs

A word of caution on this. Pete Llewellyn is taking over a chaotic stock position and lots of phone calls about specific requirements will get in the way of sorting things out properly. Communicating with Len Newman has been difficult for many months and he had not been open about the extent of the ...
by andrew jukes
Wed Nov 07, 2012 12:21 am
Forum: Track and Turnouts
Topic: Super Elevation
Replies: 21
Views: 6708

Re: Super Elevation

Here’s the nearest I’ve got to a crossover on a canted curve. IMG_0211.jpg The double track main line curves to the left before the much sharper curve to the right in the background. The curves in the foreground are what I term ‘all-transition’ curves - they tighten to (momentarily) 6 metres radius ...
by andrew jukes
Mon Oct 29, 2012 6:49 pm
Forum: Track and Turnouts
Topic: Super Elevation
Replies: 21
Views: 6708

Re: Super Elevation

A few more comments: - The trackbed in the canted curve has to take up the shape of a slice of the surface of a very shallow inverted cone, if you can picture that! What this means is that, even where the cant is constant, the trackbed has to be able to be distorted. I have used very well supported ...

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