moving things?

Question

how does hydraulics and pneumatics move things?
good answer and get 10 points

Answer 1

Hydraulics moves things by pressurizing liquids to produce forces large enough to move very heavy objects.

Pneumatics moves things the same as hydraulics, but by using pressurized air or gases instead of liquids.

Answer 2

Let us say that you have a Hydraulic pump connected by a 1" dia. pipe to a cylinder containing a piston with a head area of 20in².
The pump, connecting line and cylinder are full of hydraulic fluid. The pump is started and puts out a pressure of 300psi.
In the fluid filled system, (being incompressible), the pressure goes to 300psi instantly and acts on the surface area of the piston. We then have 300psi acting on a 20in² area.
This produces a TOTAL FORCE of 20in² x 300psi = 6000 pounds force. This power is used to do work, like operating a hydraulic jacking machine.

Pneumatic systems operate in a similar way as in a pneumatic control system in a process fluid line in industry.
A large area diaphragm in a casing, is fitted to a control valve which is controlling a process flow at 400psi.
The diaphragm is connected by a shaft (stem) to the plug of the control valve. Assume that this plug has an area of 2in². The line pressure of 400psi below it is trying to push it upwards with a force of 2 x 400 = 800pounds..
The diaphragm has a powerful spring installed set to oppose this force and keep the valve closed (or open as requirements demand).
The diaphragm has a radius of 10" making its area 314in².
Even at the lowest air supply pressure of 3psi, the diaphragm will oppose the spring and begin to move the valve plug due to the force of 3psi acting on the 314in² area = 942 pounds force which begins to compress the opposing spring and, as the air pressure increases, the force becomes greater and the valve opens wider. By controlling the air to the diaphragm, the flow or the pressure of fluid within the pipeline is controlled.

(That's about as basic as I can get. There's a whole lot more to the controls associated with such systems).

Answer 3

"HOW" GOES LIKE THIS. HYDRAULICS AND PNEUMATICS USE THE SAME PRINCIPAL, HYDRAULICS USES LIQUID AND PNEUMATICS USES AIR.

A SMALL PISTON, SAY WITH A FACE AREA EQUAL 1 SQUARE INCH , IS PUSHED FROM BEHIND INTO A CYLINDER THAT IT FITS INTO NICE AND SNUG. THIS SMALL PISTON PUSHES THE FLUID IN FRONT OF IT FROM THE SMALL CYLINDER INTO A BIGGER CYLINDER AND PISTON, SAY WITH A FACE AREA OF 10 SQUARE INCHES. WHEN WE PUSH ON THE SMALL PISTON WITH ONE POUND FORCE THE LIQUID TRANSFERS THAT ONE POUND OF FORCE AGAINST THE 10 SQUARE INCHES OF THE LARGER PISTON MAKING THE FORCE AGAINST THAT PISTON 10 POUNDS. THE FORCE FROM THE SMALL PISTON TO THE LARGE ONE HAS BEEN MULTIPLIED TEN TIMES. THE TRADE OFF IS THAT THE LARGER PISTON ONLY MOVES 1/10th AS FOR AS THE SMALLER ONE DOES. THIS WHOLE PROCESS WORKS IN REVERSE ALSO; TEN POUNDS OF FORCE AGAINST THE LARGE PISTON MOVES THE SMALL PISTON WITH ONE POUND OF FORCE TEN TIMES FARTHER THAN THE LARGE PISTON MOVED.