To address the problem with coal unloading jams-- my thought was to use a Walthers ore dock fixed up with several actuator trips so that a cut of cars would be unloaded over several bays. The movement and multiple trips might by-pass the jamming problem.Couplers - I've always preferred Kadee, especially since the Model Railroader article referring to breakage of the newer knuckle coupler types. However, some of the newer types fit the plastic talgo trucks without modification. They DO REQUIRE several washers/spacers/shims to control coupler droop but these things line up easily on the built-in mounting pin. The sides of the plastic "mounting box" can be removed and a Kadee #5 with draft gear can be cemented in place over the plastic mounting pin. I've had trouble with the Kadee #523 wheelsets - seem to be too long to fit the plastic trucks without binding. I've used Intermountain and Proto (LifeLike) wheelset replacements on the C&O, Reading, VGN, B&M only because the wheel colors compliment the car color. LBF, JayBee, wheelsets on the CB&Q, also for the same color compliment. Later weathering applied will look better. The PRR will get KADEE 2Df8 class trucks just for show. The MONON Cement Service hopper received KATO Rollerbearing trucks. When weathered, the rollerbearings can be seen to move when the car is in motion. Another hobbyist gave me this idea - and it is soo-o-o kew-l!
Couplers to the metal talgo trucks require some tinkering.
Metal talgo trucks with the wide tongue and no metal tabs -- Remove the truck from the car. Remove the cover that holds the coupler. Remove the NMRA coupler. Tap the hole on the tongue to receive a 0-80 screw (3/16" long). Mount the entire Kadee #5 with draft gear box, screwing downwards towards the track. The draft box will also accommodate a 2-56 screw but the hole in the talgo tongue will have to drilled out and tapped. A touch of adhesive will hold the draft gear box and screw securely without the need to overtighten. (I've also used the cover box with just a Kadee #5 coupler and the copper centering spring. Remove the rivet pin from the cover. Tap for a 0-80 screw. A clearance hole in the tongue must be drilled out, enlarged with a #50 drill. The screw is driven upwards from trackside to secure the cover in place.)Replacing wheelsets in metal talgo trucks-- A real pain. You'll want to use a wheelset with PLASTIC WHEELS. Metal wheelsets and metal axles in these frames is just asking for a dead electrical short either rail-to-rail through the truck or along the diecast frame truck-to-truck. Walthers (#933-1006) has a set -- plastic wheels, nonmagnetic brass axles. Remove the truck from the car. Locate "dimples" on the truck where the (soft steel) bolster inserts into pockets on the diecast sideframes. Looking down onto the topside, the dimples are about 2-3mm in size, one at each end of the bolster. The dimples on the bottom are pinhead sized. Turn the truck onto its back supported only near its screw hole. Apply downward pressure to the sideframes equally, while applying some pressure to spread these sideframes apart. This should allow for easy removal of the OEM wheelsets, and permit placement of the new wheelsets. With the truck still on its back move supports to the dimpled areas on the sideframes. Apply downward pressure to the screw hole location until the soft steel bolster bends back into position. This bend is limited by the length of the axles on the new wheelsets, and should allow the axles to spin freely without binding, and just be retained in the sideframes. Set the truck on a track to check alignment -- all four wheels should be tracking. Pliers can be used to make small adjustments, twisting the truck.
Bending of the soft steel bolster might solve some of the problems with height vs. non-working gates on the hoppers. I've also used padded jaws of a vise to apply pressure to the sideframes while pushing downwards to close the distance between the sideframes. I've also bent axles and broken sideframes with too much force.
I replaced the OEM trucks on the sugar hoppers with Atlas 70-ton trucks (more appropriate for the rated loading of the hoppers) It looks like that was a bad idea - the cars ride high now, and only grinding down the centering posthole will enable the hopper gates to work properly.