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Probably the most important factors in designing a layout and selecting rollingstock to achieve optimum operation, are standards. These will cover a multitude of facets on trackwork and rollingstock parts effected by it; along with others associated. In addition to those established by the NMRA, others must be developed specifically for your pike. Determination may seem time consuming and laborious, but the rewards far outweigh the effort. In the early days, utter chaos existed, preventing interchange of equipment from one layout to the next. Scales, gauges and couplers differed, eliminating possibility to run equipment on a friend's track. Motors were AC, DC or universal; with some at 6v, 12v or 25v ratings. Clearances and flangeways differed from flange dimensions at the whim of the maker. This total confusion instigated the foundation of the NMRA in order to set standards for interchange. The original set grew to include almost every scale and gauge. Later Recommended Practices were included as guidelines for factors not directly effecting interchange. The only factor not resolved was couplers; due a divergence in preferences. In more recent years standards were developed for Digital Command Control. These should have been RP's, since they will tend to inhibit future development to match the state of the art. As suggested by John Armstrong in "Layout Design for Practical Operation", every layout should have its own set of standards established before design. First a scale and gauge must be decided, influenced by the availability of rolling stock, trackwork and structures for the era chosen and the dimensions of the alloted space for the layout. Smaller scales, older eras or narrower gauges require less space, but larger scales permit more detail without over taxing eyes and skills. A thorough study, of the NMRA Standards and Recommended Practices and other sources, is advisable to help determine layout standards. Often influenced by the layout dimensions, the minimum radius of CURVES will determine the maximum usable rollingstock lengths and wheelbases. Large road locos or 85' passenger and freight cars do not perform well on sharp curves. Coupler swing may also influence choice. Turnout radius of closure should be commensurate with minimum radius. Road tangent track centers are usually established by those offered in commercial crossovers; while in yards finger access to rerail equipment sets the minimum. For example, in HO, most crossovers are on 2" (14.52'), while the prototype is 1.79" (13'). Widening is required on CONCENTRIC CURVES to prevent side swiping. The NMRA RP is safe but can be refined to save space by carefully measuring intended equipment use. Additional roadside clearances may be determined in the same manner. EASEMENTS will improve both operation and appearance. Paradoxically, by consuming space through length, they produce their greatest advantages on sharp curves, which are used to conserve space. If used, a minimum length should be set. Hand in hand, maximum GRADE and WEIGHTING SYSTEM will determine train lengths. Light locos with lower drawbar pull and heavy cars reduce length drastically on grades. Th only COUPLER standard set by the NMRA is the center height above the rail head; however a layout standard should be established for all equipment that are intended to intercouple. Although they may be from different manufacturers, they should be checked for desired functionality and compatibility. For optimum operation, it is mandatory that all rollingstock and trackwork be checked for conformance to NMRA Standards. In most cases corrections are easily made. STANDARDS GAUGES covering most of the critical mechanical dimensions are offered and should be used. Other gauges may augment the NMRA's to cover factors not included. Once established, both the NMRA and the specific layout standards should be adhered to very strictly. Wandering outside the set limits will almost certainly lead to undesirable problems. BACK TO MEASURING INDEX |
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