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NOTE: In development state. In general couplers cause more grief than most other devices. Not only in incompatibilities and operation, but also in MOUNTING and selection. With the wide variety available, there are many incompatibilities ; not only with different types, but with those that claim compatibility. Operation can vary from very good to very poor dependent on how you play trains. A glance through a magazine index will show the numbers of mounting problems by the quantity and frequency of articles. Unless you like to waste time, effort and money, converting several times; early selection of the best type is highly desirable. Since there is much controversy and hype in both ads and articles, confusion reigns. Unfortunately none of the manufacturers publish the necessary selection data, such as swing to aid decision. Probably most beginners start with the couplers included with sets or individual pieces and these are sufficient for the casual Christmas tree layout. As interest grows and yards are added, attention demanding problems may arise. Possibly from a desire for more realistic appearance or better operation, new couplers are indicated. The basic questions are what and how. Before jumping in with both feet, it is wise to understand the possibilities and the problems. Layout minimum radius and equipment geometry are the major factors to consider before doing anything. Some combinations of curves and rollingstock can not be readily resolved with any couplers on the market. Examine the curve-coupler interaction discussion under CURVES for some examples. In short, long wheel base rolling stock and small radii just do not agree and this holds true with coupler usage. Other than appearance, the major advance in operation is magnetic uncoupling followed by delayed action. The first reduces the possibility of mechanical snags, while the second permits uncoupling at a magnet and pushing a car any distance to its final resting place. In N scale Rapido couplers usually suffice with three exceptions. They do not look realistic in appearance, they lack delayed action and car separation is atrocious. Although magnetic knuckle couplers drastically improve appearance, they reduce coupler swing and gathering on curves, and do not provide prototypical car spacing. Other small scales face similar problems. In HO, the common horn hook coupler can create many problems and derailments due to side torque from the spring. This is particularly noticeable with talgo trucks and worsens as truck wheel base reduces. The combination of shank and drawbar length with spring force form a long compound lever system, which skews wheels into railheads. Along with small radii and short turnouts this probably causes the vast majority of derailments, particularly while pushing. Body mounting reduces, but does not eliminate the problem. Delayed action is not available. Due to lack of quality control and poor casting, many imported horn hooks perform badly. Fortunately as of 2002, these are being phased out, being replaced by McHenry types with knuckle springs. NOTE: The following expresses my own opinion of findings during evaluation, backed by experience in installing thousands of couplers, since about 1951, for my equipment and that of customers. However some input is derived through feedback from fellow modelers and customers. Found on other pages are discussions on CLOSE COUPLING and a more TECHNICAL EVALUATION Disagreements or alternate views can be posted at MR COUPLER HELP GROUP During our new product testing, not all HO knuckle type magnetics performed equally in any criteria. Accurail, Intermountain, McHenry (Bachmann EZ ?) and Kadee plastic were included. Some of the acetal plastic couplers worked well without lubrication. But with an application of graphite for consistency, couplers were mounted in various car kits with free rolling trucks and checked for coupling, uncoupling and delayed action over a Kadee magnet. The Kadee metal knuckles were burnished with graphite to reduce friction toward that of acetal plastic. Using the familiar metal Kadee as a standard, each was compared carefully. During coupling the plastic Accumate proto had the least car movement followed closely by the plastic Kadee Although none were objectionable, the Accumate Standard Size produced the most movement, possibly due to its scissors like action, but the Proto version was greatly improved. Compatibility was good under favorable conditions. Uncoupling appeared to be about equal. Kadee, Intermountain, Accumate Proto, plus McHenry and Bachmann with coil knuckle spring provided highly desirable delayed action reliably. By sanding down the right spring on the McHenry with plastic knuckle spring, it was attained, but not as well. Thinning the curved spring evenly, without excessively thinned areas, is very tricky. Using a Weller electric sander the process took about 10 minutes of very careful sanding and testing on the first trial. A little experience reduced this to about 4 minutes. In view of the time factor, the others were not considered worth the treatment. Apparently if delayed action is desired, the extra expense of Kadee or the less expensive McHenry coil types are the only choice at this time. For the sake of economy, some of the less expensive couplers serve well in less critical services, such as unit trains, with better ones on end cars. Unfortunately, presently, McHenry does not offer offset, short and long shank versions in the coil type. Probably the same couplers, Bachmann does offer these at a slightly higher price. Mounting in common #5 compatible cast in boxes is about equal, except Kadeee requires dropping in the centering spring and slipping the shank into it, The Accumate Proto has a small mounting hole, which will not fit most cast-on draftgear studs, however its box can usually be mounted in most boxes by removing the center post and drilling a hole for mounting screw. Some may require assembly by forcing the "hose" trip pin into the plastic. Of note, almost all boxes require various thickness shims to prevent sagging of knuckles over magnets. Due to weight this is particularly bad with Kadee metals mounted in most boxes, causing "hoses" to drag on magnets even with proper adjustment using height gauge. The shim location varies, either top or bottom to achieve proper height. The use of height gauge is mandatory for good operation, since there is no "standard" car which may be used as a reference. Due to its construction , the Accumate Proto requires it own box and is not drop-in. None of the drop-in "scale" couplers deserve to be labeled scale. Only the Kadee 711 and Accumate approach the prototype length of 12" from pulling face to horn and both require surgery in cast-on boxes. In general function has not improved much in forty years, since the introduction of delayed action. Mounting problems have grown worse along with compatibility. A few devices are available to help mount or repair couplers and assemble draft gear boxes. There are also some mounting ideas that may point to problem solution . If you plan to do much work or modification, these COUPLER MOUNTING AIDS can help relieve the strain. On their site, Kadee lists many coupler conversions with good ideas; but some are antiquated, others are crude and none seem to address close coupling. With the advent of the introduction of numerous new designs plus the almost total indifference toward mounting facility, the situation has degenerated to chaos. Why should you be forced to waste your money on inferior product that require laborious efforts to achieve optimum operation and prototype appearance? Something must be done. For a more in depth and technical discussion of the incompatabilities among couplers and between them and mounts, see COUPLER TECHNICAL EVALUATION For those interested in the development and variation of ideas in coupler design, see A SKETCHY HO COUPLER HISTORY BACK TO COUPLER AIDS BACK TO CURVES AND COUPLER EFFECTS BACK TO MEASURING INDEX BACK TO METHODS INDEX BACK TO TIPS ON TESTING |
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