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Adaptor for "L'il Big Hauler" couplers

By Alec K
The Bachmann "L'il Big Haulers" range is a budget-priced set of 4w rolling stock with (as at December 2012) two dedicated steam-outline locomotives, all in the traditional American genre. The range is colourful and attractive, and is aimed at attracting youngsters to large-scale model railways in the most inexpensive way possible. As is often the case with this sector of products, the rolling stock offers excellent opportunities for modifications of all kinds, and this is exactly why I bought a "L'il Big Hauler" 4w Baggage Car. The moulding style of this vehicle (including the two sliding doors, incidentally) is identical to that used on "Big Hauler" range of vehicles.
The couplers on the budget range are simplified and work in the opposite way to the standard Bachmann and LGB hook-and-loop couplers- that is, the hook on the "L'il Big Hauler" vehicles is hinged above the loop. It is also at a different height, as the picture below shows:
By December 2012, Bachmann had not produced an adaptor for these couplings to reduce their operating height, and I therefore decided to produce my own, at the same time fitting standard hook-and-loop couplers to ensure consistent operation.
The adaptor design needs to make use of the moulded screw sockets on the underside of the rolling stock. It will be noted from the picture below that there are a number of options: the original simplified Bachmann coupler uses only one of these sockets (Hole B) and it has already been removed to enable work to commence.
The distance between the centres of Holes A and B was carefully measured, and the distance of the centre of Hole B from the inner edge of the headstock was also measured.
The centres of Holes A and B are 22mm apart, and Hole B is 7mm from the rear (inner) edge of the headstock. A rectangular adaptor block was next made from welding three layers of 60 thou Slater's Plasticard to one layer of 20 thou Plasticard with MekPak solution, creating a block whose dimensions are 45mm long by 24mm wide. A centreline is drawn down the length of the block, whose front face lines up with the rear (inner) edge of the headstock.
The standard LGB coupler is located and aligned by means of a moulded channel with a semi-circular head, as shown above. This channel is just under 8mm wide and approximately 26mm long. Using 60 thou Slater's Plasticard, a separate bar to fit this channel was cut and filed to shape, and welded to the top of the adaptor block as shown above.
Two 3mm diameter holes were drilled through the adaptor block as shown, Hole B 7mm from the front edge of the block and Hole A 22mm from the centre of Hole B, both along the centre line drawn previously. Hole B penetrates the coupler bar which shares the same centre line.
Standard LGB machine screws were used to secure the couplers and the adaptor blocks to the vehicle underside as shown, that in hole B being 20mm long overall. A shorter screw is used in Hole A.
The block enables the effective and accurate coupling of the Bachmann budget stock to standard 'European' height couplers, as can be seen above.
All that remains to be done is the cutting of a pair of blanking plates from thin Plasticard to fill the cutouts in both headstocks. The blanking plates are welded with MekPak to the front face of the adaptor block and the top surface of the coupler locating bar, as shown above.
When complete, the adaptors and the attached blanking plates are removed, sprayed with Halfords Plastic Primer, and then, when dry, painted with Humbrol 'Satin Black' to reduce their visibility. They are then reattached for use.