Module Interface

The fundamental module interface specification is here . The jigs described below produce interface hardware conforming to this specification from 1-1/2 x 1-1/2 x 1/8 aluminium angle.

Click, or [Enter], on an image for higher resolution. Return to this description with your browser back-button [Alt+left-arrow].

This jig is used to drill locating holes that are used by other jigs. This jig puts one #13 hole in a 6-1/2 inch long, single track, 1-1/2 x 1-1/2 x 1/8 aluminium interface angle, or three #13 holes in a 16-1/2 inch long double track interface angle. A drill press with suitable workpiece clamping is used to drill the holes, for accuracy.

The middle hole is precisely in the centre of the longer angle. This middle hole has never been used; it was specified in case it ever became useful. The other holes are offset 1/4 inch from the centres of their intended tracks. These holes are offset so that they do not line up when interface angles are mated; it was guessed originally that these might be necessary to separate mated angles. This might have been the case when the original industry standard parallel dowel pins were used for locating, since those tend to bind and lock-up in this application. However, because of this lock-up, it became necessary to design, make, and use, a special tapered pin. This special pin works very well and has no tendency to bind, so the offset holes are not used for angle separation. However, these holes are used to locate other jigs on the interface angle. The brass screws locate the new interface angle; these have never been adjusted after the first time, and probably should be left alone.

The separate brass tube is a 1.75 inch spacer; it has a use, probably when drilling junction interface angles, which have different plan dimensions, but its precise use is lost in the mists of time.

This jig puts one #13 and one #E interface locating holes, and three latching #19 holes in an interface angle drilled using the Track And Module Centres jig. The #13 hole houses the interface locating pin. These five holes form what is required for a single track interface, see specification, and thus the jig is used twice on a double track angle. A drill press with suitable work piece support is used to drill the holes, for accuracy.

This jig is located by the screwed pin with brass nuts into the concave side of the interface angle.

The position of an interface keeper, to which a latch is mated, controls the interface-to-interface clamping load. The Southco recommended position, used initially, yields a fearsome clamping force that is grossly excessive for this railway application. This jig was created to create the 0.665 inch keeper location hole in the interface specification. The jig is positioned on an interface angle using the interface locating hole, and a keeper hole drilled using the jig as guide.

This jig probably is obsolete, the Locating And Latch Holes jig has been corrected, I think 8-).

This image shows a double track interface angle after use of the Track And Module Centres and Locating And Latch Holes jigs, and before the locating pins and latches are fitted.

This image shows the latches, and nut and bolt assemblies, used to complete an interface. There was no locating pin available for this photograph (but every existing module has some). The lone screw and washer assembly is for attaching a locating pin to the interface. The nuts require an 11/32 inch wrench.

Locating pins have been made by a two-step process. First comes turning the module interface locating diameters, threaded bore, etc.; the second step involves reversing the pin, screwing it onto this chuck-mounted jig, and machining the taper.