Probably one of the most common groups of freight cars, these present some of the most common faults in lack of design for close coupling.
USING CAD DRAWINGS a thorough evaluation is made.
Note: On 50' Underframes that have mounts for reefer appliances, the frame holes are spaced closer than the mounting studs, resulting in downward tilt of boxes, if forced on. Holes should be reamed for an easy fit.
First the car must be measured. The end sill to end corner reference is .043" = 3.746" and the coupler box front to end sill extension = .0.036". The box front to post front is .189" and the post OD = .116" for box front to mounting center = .249". The box is .415" long. The pulling face to striker distance = .216". Found from MEASURING COUPLERS, almost any drop-in coupler will fit.
Examining the most common case, the #5 pulling face to stud rear = .540". The pulling face to mounting center with this box is .540 - .058 = .485". Of note the play between Kadee coupler hole = .132" and post is a very sloppy .016", pointing out the inconsistency of box design.
The heavy line is the end corner reference (end sheet) and the solid line to the right is the model striker. Based on prototype data, at the bottom dashed in are inside to the left at 1 1/8" for plate and sheathing . and to the right at 6 15/16"is the striker. The far right dashed line is the pulling face at 15" from the striker.
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KADEE 5 WITH 54.36" SPACING
The pulling face to reference = .312 = 27.18" for 54.36" spacing or 11.49" too wide.
Found from Measuring Couplers, the 5 pulling face to stud rear = .508". The pulling face to mounting center with this box is .508 - .058 = .450". Of note the play between Kadee coupler hole = .132" and post is a very sloppy .016", pointing out the inconsistency of box and coupler design.
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KADEE 23 WITH 48.78" SPACING
The prototype pulling face to reference is 21 15/16". The box front is within .001" of the prototype striker distance; but with only .007" clearance, it will require trimming of about .020". The pulling face to reference = .2835 = 24.70" for 49.39" spacing or 5.52" too wide.
To achieve prototype separation, there are several ways, which will require removal of center post. Conserving #5's is the most difficult, requiring replacing or moving box.
An obvious solution might be to cut off the frame box, trimming back the frame and securing a separate box. But the weight makes a poor anchor, since excessive clearance at the assembly studs permits considerable movement in all directions. Clearance holes must be drilled, to provide access to the stable floor, for mounting screws. Shims will be required to level box.
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KADEE 5 BOX WITH PROTOTYPE SPACING
The original box location is dotted, while the new is solid.
Striker to mounting center = .262", striker to box front = .011" and striker to box rear = .498"
In another method, a section of the frame between the box and the bolster may be removed to move the box back. The ensuing butt splice will require a fitted bar between the sills to strengthen joint.
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KADEE 5 IN ATHEARN BOX WITH PROTOTYPE SPACING
Striker to mounting center = .266", striker to box front = .017" and striker to box rear = .432." Box move = .060".
As shown in the lower box below, a #23 will almost fit, but at least .017" must be milled from box rear. A #5 box lid must be trimmed down to size and screwed in place, as discussed in Close Coupling. Box and lid should be trimmed to striker at least.
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KADEE 23 WITH PROTOTYPE SPACING
Lacking the ability to mill rear, the box will require moving. Striker to mounting center = .238", striker to box front extension = .011" and striker to box rear = .404." Box move = .032". Again box and lid should be trimmed to striker at least.
After removing the Athearn center post, the Accumate Pro is easy to mount, if cut down.
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ACCUMATE PRO WITH PROTOTYPE SPACING
First mark the Athearn box front to mounting center = .178". The AP box front to Athearn box front = .010", requiring lip removal and trimming Athearn box. Alternatively, the box may be trimmed to the striker and the striker to mounting center = .135".
Other couplers follow the same principles , using their measurements.
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