Closecouplers.
Posted: Mon Oct 15, 2018 10:22 pm
Not sure if this qualifies as a review; I'll leave that decision to Site Admin.
If I may be permitted to document my experiences with European closecouplers over the years on my old layout.
The purpose of closecouplers, i.e. running buffer-to-buffer round curves, is very desirable, as it improves the appearance of any train, but especially corridor coaches. One or two design principles have to be adhered to, namely: the coupler when joined must form a rigid drawbar, and must "lengthen" itself on a curve to keep the buffers safely apart. OK, we know all this. The earliest, originally developed by Röwa and introduced by Roco in the mid 1970s, created the drawbar from two parallel shafts that locked together when coupling up. Two years later pre-uncoupling was introduced. In 1985 along came Fleischmann with a sort of buckeye arrangement that incorporated pre-uncoupling from the start. Märklin joined the club in 1987, which was when I started building the old layout in Munich. The Märklin product was the only one at that time that was compatible with the European standard hook and loop coupling. When you have a load of older rolling stock with this earlier coupling, choosing the Märklin is a no-brainer. No way was I going to refit all the old coaches and wagons (not to mention the locomotives) to match either of the other two makes, nor was I going to run with a mixture of couplings.
OK, fine, rakes of corridor coaches look great without gaps between the connections. It didn't take long, however, for buried dogs (as the Germans call them) to poke their ugly heads up. These closecouplers won't do up on a curve, even one of 5 ft radius, let alone the various so-called "standard" ones. This is a consequence of the design. On a straight, the coupling is kept retracted on the centre line of the vehicle by a tension spring. When two vehicles are pushed together on a curve, the couplings are at angle to each other and kept apart by the buffers. This was why I toyed with the idea of the straight platform extensions on the new layout (that idea had to be abandoned). So I suppose I'll have to go back to standard couplings on the locos to facilitate changes of locomotive in the station. And as for shunting wagons...
In a futile attempt to counter this problem (I'd call it a conceptual design fault if I had a better idea myself, but I don't, unfortunately), Märklin have arbitrarily increased the "reach" of the coupling, giving us a gap of some 3 mm between bufferheads (and corridors) when pulling, thus throwing away the visual advantage the closecouplers were designed for in the first place. The matter of the angle of approach remains unaddressed.
Another thing I noticed is that the Märklin closecoupler does not form a rigid drawbar. There is a certain amount of play between two couplings when done up, allowing them to wiggle about a bit. When pulling a train round a curve, the couplings are pulled out against the straightening spring and drawn to the inside of the curve; the longer the train, the sharper the effect. When the train enters a straight, the straightening spring is not strong enough to retract the couplings completely and force them back to the centre line, and the drawbar gets stuck on that side of the curved guides. And because of that wiggle play, the drawbar gets kinked. When the curve goes the other way, the drawbar will not move across and the vehicles can get pulled off the track, especially on points and crossings. Most coaches can be kept in fixed rakes with the other makes of couplers, Roco and Fleischmann, which are not so wiggly, but the problem of goods trains remains unsolved.
My British rolling stock has no closecouplers (since there'll be no mixing of stock), so I'd be interested to hear of other members' experiences with them and any solutions found.
Cheers,
Artur
If I may be permitted to document my experiences with European closecouplers over the years on my old layout.
The purpose of closecouplers, i.e. running buffer-to-buffer round curves, is very desirable, as it improves the appearance of any train, but especially corridor coaches. One or two design principles have to be adhered to, namely: the coupler when joined must form a rigid drawbar, and must "lengthen" itself on a curve to keep the buffers safely apart. OK, we know all this. The earliest, originally developed by Röwa and introduced by Roco in the mid 1970s, created the drawbar from two parallel shafts that locked together when coupling up. Two years later pre-uncoupling was introduced. In 1985 along came Fleischmann with a sort of buckeye arrangement that incorporated pre-uncoupling from the start. Märklin joined the club in 1987, which was when I started building the old layout in Munich. The Märklin product was the only one at that time that was compatible with the European standard hook and loop coupling. When you have a load of older rolling stock with this earlier coupling, choosing the Märklin is a no-brainer. No way was I going to refit all the old coaches and wagons (not to mention the locomotives) to match either of the other two makes, nor was I going to run with a mixture of couplings.
OK, fine, rakes of corridor coaches look great without gaps between the connections. It didn't take long, however, for buried dogs (as the Germans call them) to poke their ugly heads up. These closecouplers won't do up on a curve, even one of 5 ft radius, let alone the various so-called "standard" ones. This is a consequence of the design. On a straight, the coupling is kept retracted on the centre line of the vehicle by a tension spring. When two vehicles are pushed together on a curve, the couplings are at angle to each other and kept apart by the buffers. This was why I toyed with the idea of the straight platform extensions on the new layout (that idea had to be abandoned). So I suppose I'll have to go back to standard couplings on the locos to facilitate changes of locomotive in the station. And as for shunting wagons...
In a futile attempt to counter this problem (I'd call it a conceptual design fault if I had a better idea myself, but I don't, unfortunately), Märklin have arbitrarily increased the "reach" of the coupling, giving us a gap of some 3 mm between bufferheads (and corridors) when pulling, thus throwing away the visual advantage the closecouplers were designed for in the first place. The matter of the angle of approach remains unaddressed.
Another thing I noticed is that the Märklin closecoupler does not form a rigid drawbar. There is a certain amount of play between two couplings when done up, allowing them to wiggle about a bit. When pulling a train round a curve, the couplings are pulled out against the straightening spring and drawn to the inside of the curve; the longer the train, the sharper the effect. When the train enters a straight, the straightening spring is not strong enough to retract the couplings completely and force them back to the centre line, and the drawbar gets stuck on that side of the curved guides. And because of that wiggle play, the drawbar gets kinked. When the curve goes the other way, the drawbar will not move across and the vehicles can get pulled off the track, especially on points and crossings. Most coaches can be kept in fixed rakes with the other makes of couplers, Roco and Fleischmann, which are not so wiggly, but the problem of goods trains remains unsolved.
My British rolling stock has no closecouplers (since there'll be no mixing of stock), so I'd be interested to hear of other members' experiences with them and any solutions found.
Cheers,
Artur