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Pull′ing-jack.

A hydraulic device for lift- [1821] ing or pulling heavy weights. It consists of a cylinder a containing a tube b pivoted with a piston c, and having a second, interior tube d passing into the foot of the pump e, which projects into the reservoir f. In operation, one of the hooks g g′ is attached to some fixed object, and the other to the weight to be moved; the water is introduced into the cistern, and the communicating valve between it and the interior tube d is closed by turning the screw h; working the lever i operates the plunger k, causing water to pass through the tube d from the cistern to the upper part of the cylinder a, into which it is discharged through apertures in the tubes b d, forcing the piston downward and lifting or drawing the object to which the hook g′ is attached a distance equal to the movement of the piston. By unscrewing the valve h the water is again returned to the cistern f as the weight is lowered.

The view shows section and elevation.

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