Abstract: In a thick materials pump with paired, preferably parallel, feed cylinders, which alternatingly deliver and intake, and with a slide, which pivots on the axis of a central channel and, for each pair of feed cylinders, connects, by way of a branch channel, the given feed cylinder with a fixed feed conduit connecting to the central channel, while, simultaneously and by means of a sealing control surface provided on the inner wall of the slide housing for each branch channel receiving the thick material and provided with an aperture for each branch channel, closing a second branch channel of the slide and freeing the intake feed cylinder, while identical pressures are developed in the branch channels of equal length, the invention is characterized by the facts that the branch channels (7, 8) are essentially aligned and, in each case, form a right angle with the central channel (9), and that the sealing control surfaces (18, 20) on the slide housing (21) are cylindrically arched.

Abstract: An adjustable personnel platform (38) is rotatably fastened on a lift tower end, with a carrying arm (42) and a pivot link (43) in the pivot plane of the elements (15, 21, 26) of the lift tower. It is automatically held horizontal through a reversable electric motor (96) and a speed translating drive (66, 67) as well as through a control surrounding a regulator with an inclination measuring device (92). The speed translating gear drive (66, 67) directly drives the rotatable part (64) of the pivot link (43). Between carrying arm (42) and the motor a plurality of direction changing couplings (81, 86) are provided. They arrest the rotation of the carrying arm (42) in both directions of rotation and release the rotary direction of the carrying arm (42) in a respective one of the rotary directions of the motor (97).

Abstract: For the remote control of construction machinery, more specially in the form of the distribution mast or boom of a concrete pump, in the invention a transmission system has a radio remote control unit whose control transmitter and receiver are joined up with the command unit and with the distributor for the solenoid valves respectively by respective plug contact connector means. The transmission mode is one using digitally encoded RF messages so that for each control function two part-messages are continuously transmitted after the connections have been made, such messages each being made up of a bit representative of the function, of address information and of a parity bit for security, and mirroring the condition of the circuits of the command unit. The receiver has a RF receiving part, a central process controller and a relay part or a D/A converter.