Hy-drau′lic Lift′ing-jack.
（Hoisting.) A portable lifting apparatus in which the power is a form of the hydrostatic press (M, in same plate). In this form of the machine, the reservoir a, pump [1149] b, and pressure cylinder c are above the ram d, and maintained in line therewith by the tubular casing c. The plunger f is operated by the lever g. Water is admitted to the reservoir a through the screwfitted opening h, and flows through the valve i into the pump-cylinder b, when the piston f is raised. The downward motion of the piston forces the water through a suitably arranged valve into the lower cylinder c, where the pressure it exerts between the head of the immovable ram and the movable pump and reservoir causes them to raise a weight placed either on the head k or projecting foot l. The machine is re-adjusted for lifting by the screw-valve m, which opens a communication between the upper and lower chambers. M′ and M′ are perspective views of a similar machine. M‴ has a hollow base and a stationary ram which acts as a guide-post. The cylinder with a protruding claw slides upon the ram.
