Figure 10-8.-Equal pressure applied at each end of a tubecontaining a liquid.Figure 10-9.-A mechanical advantage of 10.1-pound weight on each piston, however, each one willremain in its original position, as shown in figure 10-8.Thus, you see that a pressure of 1 pound per squareinch applied downward on the right-hand piston exertsa pressure of 1 pound per square inch upward againstthe left-hand one. Not only does the force transmitthrough the liquid around the curve, it transmits equallyon each unit area of the container. It makes no differencehow long the connecting tube is or how many turns itmakes. It is important that the entire system be full ofliquid. Hydraulic systems will fail to operate properly ifair is present in the lines or cylinders.Now look at figure 10-9. The piston on the right hasan area of 1 square inch, but the piston on the left has anarea of 10 square inches. If you push down on thesmaller piston with a force of 1 pound, the liquid willtransmit this pressure to every square inch of surface inthe system. Since the left-hand piston has an area of 10square inches, each square inch has a force of 1 poundtransmitted to it. The total effect is a push on the largerpiston with a total force of 10 pounds. Set a 10-poundweight on the larger piston and it will support the1-pound force of the smaller piston. You then have a1-pound push resulting in a 10-pound force. That’s amechanical advantage of 10. This mechanical advantageis why hydraulic machines are important.Here’s a formula that will help you to figure theforces that act in a hydraulic machine:In that,FI = force, in pounds, applied to the small piston;Fz= force, in pounds, applied to the large piston;Al = area of the small piston, in square inches; andAZ = area of the large piston, in square inches.Let’s apply the formula to the hydraulic press shownin figure 10-10. The large piston has an area of 90 squareinches, and the smaller one has an area of 2 squareinches. The handle exerts a total force of 15 pounds onthe small piston. With what total force could you raisethe large piston?Write down the formulaSubstitute the known valuesandUSES OF HYDRAULIC PRESSUREYou know from your experience with levers thatyou can’t get something for nothing. Applying thisknowledge to the simple system in figure 10-9, youknow that you can’t get a 10-pound force from a10-6