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US 4,787,781 AGranted
Shoring device
AssigneeWalter Lipscomb
InventorGeorge Bradberry
Life of this patent
Estimating the term…
Abstract
There is disclosed a device for shoring the side walls of a trench or the like which includes a pair of elongate rails and a pair of parallel, hydraulically extendible and contractible actuators connected at opposite ends to the rails for lowering with the rails into and out of positions between the walls of the trench, and adapted, when extended, to hold the rails tightly against the walls.
Claims3
A device for shoring the side walls of a trench or the like, comprising
- a pair of elongate rails,
- a pair of parallel, extendible and contractible actuators each connected at its opposite ends to the rails for lowering and raising with the rails into and out of positions in which the rails are opposite the walls, and adapted, when extended, to hold the rails tightly against the walls,
- each actuator including a cylinder connected to one rail and a piston on a rod connected to the other rail and sealably reciprocable within the cylinder to form a pressure chamber between one end of the piston and a closed end of the cylinder adjacent its connection to the one rail,
- each cylinder having a passageway therein connecting the pressure chamber with a fitting to which a hose may be connected for introducing hydraulic fluid into the chamber for extending the piston with respect to the cylinder, and
- a nut threadedly connected to each rod for movement lengthwise of the rod intermediate its connection to the other rail and the piston thereon,
- said nut being engageable with the cylinder adjacent its open end, when moved longitudinally of the rod in one direction, so as to prevent contraction of the rod with respect to the cylinder in the event of the loss of hydraulic fluid pressure.
3 more elements
Dependencies are inferred from the claim text.