Pete Harvey Posted November 24, 2011 Share Posted November 24, 2011 I'm looking at actual track gauges for P4 & Em so I can adapt my latest Buffer Stop Kit so it will fit these gauges. A friend of mine models in P4 and has lent me a length of track, P4 should be 18.833mm gauge but when I measure from inside rail to inside rail I get 18.66mm and before you ask it's not handbuilt track it K&L flexi track. I do not model in EM or know anyone local who does so my question is: EM is supposeed to be 18.20mm gauge, what is the actual inside rail to inside rail measurement? Can any one help? Pete Link to post Share on other sites More sharing options...
brossard Posted November 24, 2011 Share Posted November 24, 2011 I just took a quick look at piece of C&L EM track on a test plank. It measured (with digital caliper) anywhere from 18.15 to 18.3mm. This measurement will be somewhat dependent on how much pressure is on the caliper jaws when measuring - it is flextrack after all. Did you mean 18.66mm for the P4 track? Seems a lot to me, and in the wrong direction. John Link to post Share on other sites More sharing options...
PWSlack Posted November 24, 2011 Share Posted November 24, 2011 As bullhead rail leans inwards at 1:20, just exactly where is the measurement supposed to be taken (rhetorical question)? From first principles, the track gauge is therefore wider at the base than at the running edges by a little over 1%, or a little under 0.2mm in 4mm scale. It's an important consideration in buffer-stop design - especially if the rails supporting the beam are attached flush to the running rails. Check out the energy-absorbing stops at Liverpool Street Station platform ends for a good illustration of what is meant. Those sideframes lean inwards. No doubt about it. Link to post Share on other sites More sharing options...
Grovenor Posted November 24, 2011 Share Posted November 24, 2011 The usual standard is to measure the gauge half an inch down from the top, ie immediately below the gauge corner. This is what you will get using a caliper on model track so long as the rail is not leaning outwards. For your buffers just make them to the specified gauge 18.83 for P4 and 18.2 for EM They will then fit on track built using gauges and for track such as that you tested the buffer will just push the rail out a tad to where it should be. Its quite common for the C&L track to be a bit tight, the Ratio version was even worse and unuseable for P4. Regards Keith Link to post Share on other sites More sharing options...
Coombe Barton Posted November 24, 2011 Share Posted November 24, 2011 PM for you Pete Link to post Share on other sites More sharing options...
R A Watson Posted November 25, 2011 Share Posted November 25, 2011 If you look closely at this picture you will see that the contact points of the gauge are mushroom shaped and do indeed touch the rail edge just below the top surface. This is to allow for the spreading of the rail head as it is squeezed flat by the passage of many thousands of wheels during the years. The effective gauge is taken as the the nominal running corner of the rail and the position of the mushroom on the gauge is designed to compensate for the combination of 1;20 inclination and lower position of the contact point. Who will be the first to build this into model track gauges? Link to post Share on other sites More sharing options...
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