Patent ID: 7540336
Filing Date: 2009-06-02
Classification: E02D

Abstract:
1. A backfill tamper comprising: a handle having a lower end; an elongated conduit member having a lower end and an upper end that is coupled to the lower end of the handle; a piston disposed in the conduit member; a rod coupled to the piston and having a lower end that extends out of the lower end of the conduit member, wherein the piston and rod are configured to reciprocate up and down together in the conduit member; a spring disposed in the conduit member between the piston and the lower end of the conduit member, the spring configured to bias the piston away from the lower end of the conduit member; and a percussion generating mechanism having an upper end coupled to the lower end of the rod, wherein the percussion generating mechanism is configured to receive a supply of pressurized air and convert the supply of pressurized air into a reciprocating percussive force; and a supply of pressurized air configured to flow through the conduit member to the percussion generating mechanism, wherein the supply of pressurized air biases on the piston against the bias of the spring; wherein feedback from the reciprocating percussive force of the percussion generating mechanism causes the rod and piston to reciprocate up and down in the conduit member such that the direction of the feedback and the reciprocations of the rod and piston remain in phase with each other; and wherein the reciprocating movements of the rod and piston are dampened by the counteracting forces of the spring and the supply of pressurized air to thereby limit transfer of feedback from the percussion generating mechanism to the handle.