Kevin,
the ACC/Coronado cars I usually associate with the 20" lines were of several types, the Rocker Sidedump and the Gablebottom Sidedump. Both those types had Handbrakes. Even the End-dump cars had Handbrakes.
Gablebottom Sidedump.
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Photograph of facilities at the Detroit Copper Mining Co. in Morenci (Ariz.).
snipped enlargement from above showing Brakemen, count 4 and 4 cars.
Enlarged from DPL photo Z-5364 note the visible outline(or shadow) of the Brakewheel and Staff visible.
Even the End-dump cars used on one of the smaller inclines had Handbrakes, as per the cars atop the orebins
Rocker Sidedumps which I think are Denver Engineering Cars (as of the Merced Gold Mine type 2ft ga.car at Coulterville) are present on the lower track.
Another Rocker sidedump view
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