Pete the Elaner Posted October 13, 2010 Share Posted October 13, 2010 Most stock is relatively light, and free rolling compared to the real thing. Free rolling? I think not. Most models run on dry pin-point bearings. The real thing runs on roller or ball bearings which are fully greased & can coast for several miles (I've seen this happen). I cannot imagine a model rolling this freely. Link to post Share on other sites More sharing options...
Baby Deltic Posted October 13, 2010 Share Posted October 13, 2010 The Mk.1 body and underframe is steel; only some of the furnishing and panelling is wood. Indeed. And there's quite a bit of stuff on the underframe:My link Link to post Share on other sites More sharing options...
Baby Deltic Posted October 14, 2010 Share Posted October 14, 2010 Free rolling? I think not. Most models run on dry pin-point bearings. The real thing runs on roller or ball bearings which are fully greased & can coast for several miles (I've seen this happen). I cannot imagine a model rolling this freely. Try pushing a full sized MK1 coach along the track on BR1 bogies. The reason real stock rolls for miles is the sheer weight and massive inertia it has once it gets going. You can't really scale down friction and inertia in the same way as weight when you are dealing with something like a real Peak and a model Peak, for example. A model Peak will stop pretty much instantly when the power is shut off, but a real Peak weighing 138 tons with 63 tons brake force won't stop in the same distance at the same (scale) speed as the model. Link to post Share on other sites More sharing options...
Bob Reid Posted October 14, 2010 Share Posted October 14, 2010 The floors in mark ones are actually reinforced concrete sections to give the coaches some weight Link to post Share on other sites More sharing options...
RMweb Gold Oldddudders Posted October 14, 2010 RMweb Gold Share Posted October 14, 2010 Free rolling? I think not. Most models run on dry pin-point bearings. The real thing runs on roller or ball bearings which are fully greased & can coast for several miles (I've seen this happen). I cannot imagine a model rolling this freely. I would have agreed with you - until I found my Hornby Maunsells rolling away on track my spirit level said was flat! Link to post Share on other sites More sharing options...
Jenny Emily Posted October 14, 2010 Share Posted October 14, 2010 Free rolling? I think not. Most models run on dry pin-point bearings. The real thing runs on roller or ball bearings which are fully greased & can coast for several miles (I've seen this happen). I cannot imagine a model rolling this freely. I always lightly oil all of my stock and ensure before first use that the axles spin freely. Flicking an axle should result in it spinning for up to ten seconds before it comes to a halt. The difference it makes on running long trains is noticable. I was once told (probably mid 80s, so imagine this with RTR stock of that time) that rolling stock should be free running enough to roll from a standing start unaided down a piece of track with a 1 in 30 gradiant. Link to post Share on other sites More sharing options...
bertiedog Posted October 14, 2010 Share Posted October 14, 2010 Stock should be free rolling, is aways possible to add drag, to counter magnetic un-couplers etc., but they must roll well to start with, and most UK outline with pinpoints do not really run free. Have a look at the "points" under a magnifying glass, it will surprise you. Often the end is a broken tip from parting off in the lathe, and these rub the plastic badly. Also the plastic is usually ABS or polystyrene, not Delrin, which is widely used in US stock. If you want to see free running, try the 1970's Lindberg Line PTFE loaded Delrin trucks, so low in friction they roll on 1:150 easily, and will find low points on the track! Very long trains are possible, but at the cost of run away, and magnetic coupling problems. For UK free running, try the brass inserts, and re-work the tips in an electric drill with a very fine emery paper on a block. If you then want AJ couplings, add a tiny spot of grease to each bearing, or wires bearing on the axle middle.. Link to post Share on other sites More sharing options...
doggeface Posted January 3, 2011 Share Posted January 3, 2011 THe NMRA, US-based modelling standards etc group, do not much mention scale weight, but do have lots of empirically-derived data on how much model coaches and wagons should weigh to give them a chance to stay on the track during normal operations. Most RTR stuff is too light. On the other hand, while the weight of your Peak may not accurately reflect its scale, your interest might be in whether it can haul a scale load - however implausible that is in the average domestic situation! The cube root of the scale used would be correct. the linear scale = 1/72 = 0.0139 area scale = 1/72 x 1/72 = 0.000193 (1/72)² volume = (1/72) cubed = 0.00000268 If the prototype weighs in at say 125 tonnes then the scale weight will be: 125 x 1000Kg x 2.68 x 0.000001 = 0.335Kg = 335 gms This oddly enough is the actual scale weight of many rtr models! Link to post Share on other sites More sharing options...
RMweb Gold Colin_McLeod Posted January 14, 2011 RMweb Gold Share Posted January 14, 2011 Quite some coincidence given all the pluses and minuses. Plastic lighter than steel, but with a big heavy chassis block. In theroy if the model was made with the same materials as the prototype to absolute scale, including thickness of materials, and all internal parts modelled (including the engine and all moving parts), then the weight of an OO model should be exactly the weight of the prototype divided by 72 cubed. It might be easier to test this with something simpler such as a wagon. Link to post Share on other sites More sharing options...
buffalo Posted January 14, 2011 Share Posted January 14, 2011 ...the weight of an OO model should be exactly the weight of the prototype divided by 72 cubed. No, the axles and frame spacers are shorter, so it will be a little bit lighter Link to post Share on other sites More sharing options...
RMweb Gold Dagworth Posted January 14, 2011 RMweb Gold Share Posted January 14, 2011 The cube root of the scale used would be correct. the linear scale = 1/72 = 0.0139 area scale = 1/72 x 1/72 = 0.000193 (1/72)² volume = (1/72) cubed = 0.00000268 If the prototype weighs in at say 125 tonnes then the scale weight will be: 125 x 1000Kg x 2.68 x 0.000001 = 0.335Kg = 335 gms This oddly enough is the actual scale weight of many rtr models! One BIG error in this, 4mm/ft is 1/76 not 1/72! Andi Link to post Share on other sites More sharing options...
bertiedog Posted January 14, 2011 Share Posted January 14, 2011 1/76.2 Link to post Share on other sites More sharing options...
bertiedog Posted January 14, 2011 Share Posted January 14, 2011 And it is impossible in practical terms to make a model too heavy, unless depleted uranium is used. OO diesels should be as heavy as the motor(s), will bear, simple as that. Scaling weight is for Laboratories, we live in the real world........... Link to post Share on other sites More sharing options...
RMweb Gold Colin_McLeod Posted January 14, 2011 RMweb Gold Share Posted January 14, 2011 No, the axles and frame spacers are shorter, so it will be a little bit lighter LOL, but I did say made to absolute scale. Link to post Share on other sites More sharing options...
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