Model: 139 Gravity Drop Hammer
In this model, the rod is raised by the action of the revolving cam against the green lift collar. These are used for crushing rock to extract the ore and are generally mounted in gangs, having a large number in line.
[Virginia Downward & William M. Clark, 1930]

[Editor’s Note: In the original Newark Museum model of 1930, both models 138 and 139 were on the same panel, 138 being a partial rack and pinion drop hammer. In the Boston Museum of Science, the right-hand model of 138 has replaced a typewriter key mechanism in 139. The action of the lift mechanism in 139 is like a cam mechanism. FCM]

Francis Moon 2005-00-00

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