Concrete pumps contain two hydraulic cylinders, or cylindrical chambers that each carry a piston moving in opposite directions, maintaining constant pressure on the concrete. A valve allows concrete discharged from the pistons to flow into one pump discharge line.
The concrete pump valve type is often determined by the pump manufacturer. Gate-type valves contain two separate valves, one of which opens or closes to control incoming concrete, and the other controls outflowing cement. Rock valves are single element valves that pivots to open the intake cylinder during the forward stroke of the piston. When the piston ends its stroke, the rock valve pivots again to connect the cylinder to the pump discharge line.
Concrete pumps can either be boom-type or line-type. Boom concrete pumps attach to a trailer and use a boom, or remote-controlled robotic arm to move the concrete. Line concrete pumps either mount on a truck or reside in a trailer, and use rubber or steel hoses connected to the outlet of the pump, which sends the mixed concrete to its final destination.