Patent attributes
A pneumatic post driving apparatus comprises an internal cylinder chamber within which a hammer piston is reciprocated. The hammer piston strikes against an anvil, which in use is abutted against the top of a post to be driven. Kinetic energy from the descending hammer piston is transferred through the anvil into driving energy for the post. An air control system alternately routes pressurized air between the top and bottom ends of the cylinder to move the hammer piston up and down. The air control system includes a spool-type control valve disposed for sliding movement within a control body. The anvil is resiliently suspended at the bottom of the cylinder chamber by an annular retention flange that has a conically tapered under surface. A lower elastomeric pad fits against the tapered under surface of the retention flange in direct surface-to-surface contact.
