I recently came across a photo of a Norfolk and Western SD40-2 that had triple brake cylinders. This made me look up photos of SD40’s and it seems most had a brake cylinder on the forward and aft axle of each truck. Does anyone know the story about this? Was triple cylinders a buyer’s option? I had always thought that the SD40 had brakes on each axle.
We had an ex-nw sd40-2 as yard power. 6 pistons per truck, double clasp brakes. Stopped on a dime and gave you 9 cents.
Paired with a 6 axle slug with double clasp brakes. That set had 48(!) brakeshoes combined.
Having 4 axles with single clasp brakes is just cruel for yard work.
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Most SD40-2’s were delivered with single shoe brake rigging, meaning one shoe per wheel. These were composition brake shoes. One of the cylinders operated two shoes, the other one shoe. Clasp brakes, where a single cylinder operates two shoes, one on each side of the wheel with connection straps straddling the wheel at the level of the pedestal tie bar, about 7" above the rail. Clasp brakes could be set up to use cast iron or composition brake shoes at the railroad’s option.
Prior to the early 1960’s, clasp brakes with cast iron shoes were used on most all locomotives - the development of the composition shoe, one per wheel, was spurred by wayside fires from brake shoe sparks and became the standard on road power.
Dave
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