Patent ID: 7802914

Claim:
A concrete mixing truck for transporting concrete from one location to another comprising: a chassis including: a frame, a first power source coupled to the frame, wheels coupled to the frame, and a first drivetrain coupling the first power source and the wheels; a mixing drum coupled to the frame and to a second drivetrain, the drum comprising: a wall including an inner surface defining a volume and an outer surface; and at least one formation coupled to the wall and extending from the inner surface of the wall, the formation including a body, a support member and at least one spacer disposed proximate the support member, the body including a base region, an intermediate region and an end region, the support member and the at least one spacer being embedded within the end region, the at least one spacer being a helical spring that resiliently engages and substantially surrounds the support member, the helical spring extending from the support member to an exterior of the body.