A support is provided, comprising a first bar with a first abutment element, a second bar with a second abutment element, and a guiding device by which the first bar is displaceably guided on the second bar. An actuating device which acts on the first bar and which comprises an actuating element is arranged on the second bar. A displacement of the first bar in a first direction of displacement can be initiated by actuation of the actuating element. The first direction of displacement is a direction of increase in distance between the first abutment element and the second abutment element. The actuating device comprises a blocking device which blocks a displacement of the first bar in relation to the second bar in a second direction of displacement, which is opposite the first direction of displacement, at least when no active releasing action occurs at the blocking device.

A shoring support structure (3) comprising an outer tube (2) having a threaded region (22) with opposing longitudinal slots (16) and an inner tube (4) slidable within the outer tube and having a plurality of pairs of transverse holes (14) at spaced apart intervals. The inner tube and outer tubes terminate in a plate (6) and a pin (10) is receivable through the slots of the outer tube and a pair of transverse holes of the inner tube. A collar (8) is mounted on the threaded region and is rotatable to raise and lower the pin within the slots. The collar includes a driven member (30) such as a bevel gear for mating with a driving member (32) such as a pinion connectable to an actuator (38), actuation of the driving member causing rotation of the driven member to effect rotation of the collar (8) to move the pin.

A multi-stiffener for civil engineering and construction includes an outer pipe member, an inner pipe member, an inner pipe position adjusting pin and a positioning member. The outer pipe member includes an outer pipe strut plate provided at one end of the outer pipe member, a pair of slot-shaped symmetrical guide holes extending in a longitudinal direction from a position spaced apart by a predetermined distance from an open end of the outer pipe member, and a height-adjustment-purpose external thread formed around the guide holes. The inner pipe member includes an inner pipe strut plate provided at one end of the inner pipe member and a plurality of symmetrical through-holes formed at specific intervals from the inner pipe strut plate. The inner pipe position adjusting pin is configured to penetrate the guide holes of the outer pipe member and the through-holes of the inner pipe member.

A multi-stiffener for civil engineering and construction includes an outer pipe member, an inner pipe member, an inner pipe position adjusting pin and a positioning member. The outer pipe member includes an outer pipe strut plate provided at one end of the outer pipe member, a pair of slot-shaped symmetrical guide holes extending in a longitudinal direction from a position spaced apart by a predetermined distance from an open end of the outer pipe member, and a height-adjustment-purpose external thread formed around the guide holes. The inner pipe member includes an inner pipe strut plate provided at one end of the inner pipe member and a plurality of symmetrical through-holes formed at specific intervals from the inner pipe strut plate. The inner pipe position adjusting pin is configured to penetrate the guide holes of the outer pipe member and the through-holes of the inner pipe member.

A G-hook for the mutual releasable connection of two prop portions of a telescopic construction prop has a pin and a hoop. The pin and the hoop are different, separate parts which are rotationally rigidly connected to one another, meaning the pin cannot rotate relative to the hoop because they are rigidly fixed to one another. The pin has a force introduction portion with a surface which is curved regionally and a force removal portion which is diametrically opposite the force introduction portion and whose surface is formed substantially planar.

A locking pin 240 for an extendable structure, such as a acrow prop, having a first protrusion 244 and a second protrusion 248 extending from the shaft 242 of the pin, the first protrusion 244 extending from an intended lower surface of the shaft and having a curved inner wall facing towards the centre of the shaft and the second protrusion 248 extending from an intended upper surface of the shaft 242 and forming a box-like structure having a recess 245 for receipt of a leash 250.

A locking mechanism for locking an inner tube with an outer tube of an adjustable telescopic push-pull prop assembly is disclosed. The locking mechanism includes a slotted prop nut having a slot and adapted to move in either direction when rotated on the outer tube having threads, a guiding ring adapted to be accommodated in the slot of the slotted prop nut, and a captive grooved pin assembly adapted to be accommodated in the guiding ring for locking and unlocking the inner tube and the outer tube such that the slotted prop nut encases the guiding ring and the captive grooved pin assembly. The positioning of the captive grooved pin assembly is such that it does not hinder the rotation of the slotted prop nut.