Re: Duryea underframe usage

Anthony Thompson <thompson@...>

Al Kresse wrote:
C&O cabooses also had Duryea underframes for a while. To "cushion" you need to generate heat or wasted energy to reduce/absorb longitudinal shock loadings. The Duryea spring system did get some sliding friction to absorb some of the energy . . . but not like a shock absorber.
You are right about the Duryea underframe--its main feature was the spring action, which does help with slack action, but really does NOT cushion the load very much. As you say, to reduce shock loading, energy has to be absorbed, for example in a stack of interleaved friction plates. Of course springs absorb energy when exercised, but they STORE it almost completely, and eventually will release it when loads are reduced. That can even out slack action, but does NOT reduce peak loads due to shock or impact. That's why later cushion underframes entirely superseded the Duryea-type designs.
At least that's how I understand it.

Tony Thompson Editor, Signature Press, Berkeley, CA
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