Abstract: A pump assembly has a hopper adapted to hold a wet concrete mass and having a front wall formed with a front port centered on a front axis perpendicular to the front wall at the front port and a rear wall formed with two rear ports centered on respective rear axes perpendicular to the rear wall at the rear ports and generally parallel to the front axis. Respective piston pumps secured to the rear wall outside the hopper over the rear ports are operable to draw portions of the mass out of the hopper and expel them back into the hopper through the respective rear ports. An outlet conduit is connected to the front wall outside the hopper over the front port and a distributor pipe in the hopper has a front end fitted and aligned with the front port and a rear end engageable over and alignable with either of the rear ports. A buttress formation fixed on front end of the distributor pipe defines outside the hopper a buttress plane parallel to the front and rear planes.

Abstract: A concrete pump comprises a pair of separate pump assemblies each having a cylinder, a piston subdividing same into a piston-side front compartment and a rod-side rear compartment, and a piston rod connected to the respective piston and extending out of the respective cylinder through the respective rod-side rear compartment. The pump also has a liquid supply having a high-pressure side and a low-pressure side for supplying liquid under high pressure at the high-pressure side and for taking in liquid at the low-pressure side.

Abstract: A pump assembly for concrete comprises a hopper adapted to hold the mass and having a front wall formed with a front port centered on a front axis perpendicular to the front wall at the front port and a rear wall formed with two rear ports centered on respective rear axes perpendicular to the rear wall at the rear ports and generally parallel to the front axis. Respective piston pumps secured to the rear wall outside the hopper over the rear ports can draw portions of the mass out of the hopper and expel the drawn-out portions back into the hopper through the respective rear ports. An outlet conduit is connected to the front wall outside the hopper over the front port. A generally curved or nonstraight distributor pipe in the hopper has a front end engaged over and aligned with the front port, a rear end engageable over and alignable with either of the rear ports, and a generally arcuate centerline crossing the front axis at the front port and extending parallel to the rear axes at the rear wall.