By: Dave Hammer
Upper Rocker Arm

This picture provides a good view of the rocker arm and hammer linkage. I used pillow blocks I found at a salvage yard for both the rocker arm and treadle. They were $6-8 each. The rocker arm is 3/4 by 4" solid bar ( I would have used 1" if I had it). The linkage bars on the top of the pushrod were cut so they could be welded 3/4 inches apart so they were close to the rocker arm. The rocker arm has heavy collars welded in the center for support with the pin through the pillow blocks. All the pillow blocks have floating bearings so everything didn't have to perfectly line up (but of course they did).

The top of the hammer has a 3/4 by 2" bar welded across it. The linkage piece that provides the interface between the rocker arm and top of hammer is just two 3/4 by 2" bars with a shorter bar of the same dimensions welded in the middle (actually a little down from center) of it. This provides a tight sliding fit for the rocker arm and top of the hammer. This piece of linkage is necessary so the hammer can go straight up and down without binding with the rocker arm.