Warsop Benjo power rammer. 1:50 video:
https://www.youtube.com/watch?v=hFlmZUn5Hm8
A diagram from the manual:
https://s3-us-west-1.amazonaws.com/h...mer_manual.jpg
I'm wondering if this is the relevant patent, for a "Rock Drill and Like Implement", issued to H. E. Warsop in 1934:
https://s3-us-west-1.amazonaws.com/h...mer_patent.jpg
More: US patent #1981764
Previously: https://www.homemadetools.net/forum/...1250#post74040