The Hydraulic press is a class of Machine tool that enabled the Industrial revolution. Forming of sheet materials had previous required the material to be formed by hammering and shaping by hand with chisel and mallet. There had been previous press technology Screw press but these had significant limitations the biggest being the obtainable press pressure. Modern hydraulic presses are capable of pressure at the head of 2000 tons and can cold form metal. Other application of hydraulic presses are the compositing of material in the brick and concrete industry allowing complex shapes and production lines.
The hydraulic or bramah press depends on Pascal's principle: The pressure throughout a closed system
is constant. At one end of the system is a small area piston driven by a lever to increase the mechanical advantage. The small-diameter tubing leads to the other end of the system. This is
a large area piston that exerts a large force equal to the force exerted on the small piston, multiplied by the ratio of the areas.
The hydraulic press was made practical by Joseph Bramah's 1796 development of an oil impregnated leather gasket that sealed the large-diameter piston:
- <math>\frac{F_1}{A_1}= \frac{F_2}{A_2}<math>
Applications of Hydraulic Principle
- Used for weighing vehicles. The vehicle is placed on the larger piston while the smaller one is attached to an appropriate scale. Used to test if a vehicle exceeds mass limit for bridges.
- Used to print serial numbers on bank notes.
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