These cars are typical of those circa 1880, when Janney couplers were introduced. Having a short wheel base, they can negotiate an 18" R nicely, but their narrow platform end sills, which only extend .052" past the end corners, prevent achieving the usual close coupling spacing of 9" between ends. From an examination of prototype drawings and comparison, a workable solution can be attained by addimg the missing end face plates and circular buffers.
USING CAD DRAWINGS a thorough evaluation is made. The KD 711 mid posistion symbol was superimposed on car data and modifications added. The heavy line is the original platform endsill, whilr the blue line is the added face plate and the yellow is the plate extension, where the 4 1/2" distance is set.
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KD 711 MID POSITION
The next drawing shows a check of the end in the mid position with no pull on spring, while on an 18" R. The face plate is added to increase width of the sill along with the extension for spacing measurement between plates as with the prototype. Buffer is added at 6" from sill plate to check effect..
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CHECK ON 18" R
The end corner clears by .016" and the buffer extends .015" beyond pulling face. This provides more than enough clearance when pushing.
As a compromise between operation and appearance, the modification is relatively easy. In most cases the plate spanned the endsill flat, while some wrapped around for several inches on the sloped section. A little thick, to widen sill, a .015" X .080" Evergreen strip is added to the flat, flush with the top. Ends may be bevelled to match slope. Next, a .030" X .100" strip is cut to about .15" for the extension and centered flush at top. This may be curved and notched at outside corners for the purist.
The couplers will be body mounted, so the drawbars are cut from trucks. Set the mounting center back .294" from end plate and shim to correct height..
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ENDSILL MODS
Obtain a pack of 19 gauge = .047" wire nails which should have .091" OD heads, close to the prototype 8" = .09184". If head face is rough, smooth with a fine abrasive. Blacken these. Locate two hole centers 11" = .126" from center line of car and .046 down from top. Drill #56 holes. Mount buffers after painting sill and since heads are .016" thick, space at about .053" from plate.
Bench test on 18" R curve. Adjust buffers, if required.
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