| All Patents in class 91/31 |
Patents 1 -
8
of 8
      |
| Picture | Number | Date | Patentee | Title |
| | 1,036,842 | Aug. 27, 1912 | C.L. Heisler | Valve Reversing Gear |
 | 1,087,799 | Feb. 17, 1914 | W.H. Snow, L.F. Massey | Elastic-fluid hammer |
 | 1,722,506 | Jul. 30, 1929 | H.G. Sahlin | Drop hammer |
 | 1,924,545 | Aug. 29, 1933 | W.H. Fitzgerald, R.P. Fitzgerald | Drop hammer |
| | 1,976,122 | Oct. 09, 1934 | F.S. Haas | Hydraulic Drive for Grinding Machines |
 | 2,525,127 | Oct. 10, 1950 | H.J. Siekmann, W.R. Meyer, W.F. Groene | Hydraulic feed and control mechanism |
| | 2,612,184 | Sep. 30, 1952 | W.I. Evans | Sensitive Hydraulic Tracer Valve |
| | 3,016,804 | Jan. 16, 1962 | J.G. Osburn, F. Zankl | Program Control System |
