This is a hammer that was demonstrated at the Fall NWBA conference.
The head weight was about 65 Lb. The motor is a 1 1/2 HP 3 PH driven by a VFD.
The motor drives a 5 to 1 hollow shaft 90 Deg gear box.
The out put of the gear box drives the shaft connected to the leaf spring that is connected to the head.
The foot pedal controls the VFD and lets you control the speed of the hammer.
Like any mechanical hammer, the faster it goes the harder it hits and the VFD gives very good speed control.