| All Patents in class 91/31 |
Patents 1 -
7
of 7
      |
| Number | Date | Patentee | Title | Type |
| 1,036,842 | Aug. 27, 1912 | C.L. Heisler | Valve Reversing Gear | steam engine valve gear |
| 1,722,506 | Jul. 30, 1929 | H.G. Sahlin | Drop hammer | drop hammers |
| 1,924,545 | Aug. 29, 1933 | W.H. Fitzgerald, R.P. Fitzgerald | Drop hammer | drop hammers |
| 1,976,122 | Oct. 09, 1934 | F.S. Haas | Hydraulic Drive for Grinding Machines | grinding machines |
| 2,525,127 | Oct. 10, 1950 | W.F. Groene, H.J. Siekmann, W.R. Meyer | Hydraulic feed and control mechanism | crankshaft lathes |
| 2,612,184 | Sep. 30, 1952 | W.I. Evans | Sensitive Hydraulic Tracer Valve | hydraulic apparatus |
| 3,016,804 | Jan. 16, 1962 | J.G. Osburn, F. Zankl | Program Control System | milling machines |
