Post driver apparatus

A post driver apparatus comprising:

• a housing having a length with a top end and an opposite bottom end and an interior bore extending through the housing between the top end and the bottom end, the housing having a too wall at the top end of the housing, the housing having an opening at the bottom end, the opening providing access to the interior bore from an exterior environment of the housing through the opening;
• a piston mounted in the interior bore for reciprocating movement of the piston through the interior bore, the piston having a plurality of projections on a side of the piston;
• a shaft mounted on the housing for rotation of the shaft;
• a drive wheel attached to the shaft for rotation of the drive wheel with rotation of the shaft;
• a spring in the interior bore between the top end of the housing and the piston, the spring having a lent with one end of the spring engaging against the top wall of the housing and an opposite end of the spring engaging with the piston and urging the piston to move through the interior bore from adjacent the too end of the housing toward the bottom end of the housing;
• a plurality of pins on the drive wheel, the plurality of pins being positioned on the dive wheel where, with the piston position in the interior bore adjacent the bottom end of the housing, rotation of the drive wheel causes the pins to come into engagement with the plurality of projections on the piston, where further rotation of the drive wheel causes the plurality of pins to push upwardly on the plurality of projections and move the piston through the interior bore from adjacent the bottom end of the housing toward the top end of the housing and where still further rotation of the drive wheel causes the plurality of pins to disengage from the plurality of projections causing the spring to move the piston through the interior bore from adjacent the top end of the housing toward the bottom end of the housing;
• the piston having a hollow interior and a top opening;
• and,
• the length of the spring extending from the one end of the spring in the interior bore of the housing, through the top opening and to the opposite end of the spring in the hollow interior of the piston.