SOME HYDRAULIC PRESSURE MACHINES 529 
_ 4 inches respectively. Neglecting friction, what is the pressure of the water in 
Ibs, per square inch? 
10. In an intensifying accumulator (Fig. 836, p. 524) the diameter of the ram 
is 4 inches, and the diameter of the piston is 20 inches, If the head of water on 
the piston is 60 feet, what is the pressure of the water on the ram in lbs. per square 
inch? If the stroke of the ram and piston is 30 inches, what is the capacity of 
this accumulator in ft,-lbs, ? 
11. On board ship an accumulator is used in which the ram is 9 inches 
in diameter, and the pressure of the water is 800 lbs. per square inch. The load 
is produced by steam pressure of 60 lbs. per square inch acting on a piston 
connected directly to the ram and working in a separate steam cylinder. 
rere friction, what must be the diameter of the steam piston ? 
12. A hydraulic intensifier is required to increase the pressure of 700 Ibs. per 
square inch in the mains to 3000 lbs. per square inch. The stroke of the 
intensifier is to be 4 feet, and its capacity 3 gallons. Determine the diameters 
of the rams, [Inst.C, E.] 
13. Referring to the hydraulic intensifier shown in Fig. 837, p. 525, if the 
diameters of the rams are 24, 4, 6, and 8 inches respectively, and if the pressure 
of the water introduced into the outer cylinder is 700 lbs. per square inch, what 
are the pressures, in lbs. per square inch, which may be obtained in the pipe 
leading from the interior of the smaller ram, neglecting friction ? 
14. What would the results of the preceding exercise be if the friction of the 
_ stuffing-boxes is allowed for, assuming that the frictional resistance of one 
stuffing-box, in lbs., is equal to 0°05PD, where P is the pressure of the water in 
lbs. per square inch, and D is the diameter of the ram in inches? 
15. Ina hydraulic press for squirting lead pipes (Fig. 838, p. 526) the larger 
ram has a diameter of 20 inches, and the smaller ram has a diameter of 5 inches. 
Find the intensity of the pressure on the lead when the water pressure is 1 ton 
r square inch, and the bore of the lead pipe is } inch. If the stroke of the ram 
12 inches, and the lead pipe weighs 1:1 lbs. per foot of length, find the length 
of pipe produced in one stroke if the lead weighs 712 lbs. per cubic foot. 
16. The diameter of the ram of a hydraulic jack is 3 inches, the diameter of 
the plunger of the pump is # inch, and the mechanical advantage of the lever is 
20. If the efficiency of this jack is 75 per cent., what weight will be raised by a 
force of 70 lbs. at the end of the lever? 
17. What is the efficiency of a hydraulic crane which uses 70 gallons of water 
at a pressure of 700 lbs. per square inch in raising a weight of 10 tons to a 
height of 27 feet? 
18. In a hydraulic crane the ram is 9 inches in diameter, and the velocity 
ratio (or the ratio between the velocity of the lift and the velocity of the ram) is 
10. The water is delivered to the crane under a pressure of 1200 Ibs. per square 
inch, and the mechanical efficiency of the crane is 52'per cent. Find (1) what 
load this crane will lift; (2) the quantity of water used in gallons per 35 feet 
lift. Why do these cranes have such’a low mechanical efficiency ? [B.E.] 
19. Calculate the displacement of the ram of a hydraulic crane, whose 
efficiency is 55 per cent., in order that, with a water pressure of 700 lbs. per 
square inch, it may raise a load of 5 tons to a height of 30 feet: Find the 
diameter of the ram if its stroke is six times its diameter. 
20. A hydraulic lift with ram, load, etc., weighs 10 tons, the ram is 9 inches 
in diameter, and the friction ia the mechanism is equal to 0°05 of the gross load. 
The accumulator is half a mile away, and is loaded to 800 lbs. per square inch ; 
the diameter of the supply pipe is 3 inches. Estimate the speed of ascent of the 
lift, if the loss of head in the pipe is 0°0005/v/d, 1 being the length in feet, 
d the diameter in feet, v the velocity of the water in the pipe in feet per 
second, [B. E.] 
2L 
