Abstract: 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.

Abstract: 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.

Abstract: A new sign post driver comprises a piston which rests upon a post, well pipe or piling to be driven into the ground and a weighted cylinder which reciprocates vertically to impact the piston on the downstroke. The cylinder is raised pneumatically for each stroke and falls by force of gravity to strike an anvil on the piston. An optional spring assist on the downstroke adds to the impact thus adding to the impact for a given weight of cylinder. The result is an exceptionally light and simple post driver for its capabilities.