74 
If, for example, a force of 170 pounds is exerted on an 18-inch lever arm 
applied to a single square thread screw, Its inches in mean diameter and with 
a pitch of one-third (three turns to the inch) the approximate load (W) 
would be — 
170X18 
W = 
[0.20X3.1416X1.3125] +0.3333 
.6562 
V[3.1416X 1.3125] -[0.20X0.3333]/ - 
= 16,335 pounds^ total load applied by screw. 
HYDRAULIC PRESSES 
The formula for the calculation of the amount of pressure per square inch 
of glue joint in a hydraulic press is as follows : 
GXA 
Where — 
P=pressure on glue joint in pounds per square inch. 
G — pressure-gauge reading in pounds. 
A— area of piston or ram in square inches. 
J=area of glue joint in square inches. 
If, for example, the gauge reading G is 2,200 pounds, the area of the piston 
A is 78.54 square inches (assuming the diameter of the piston to be 10 inches — 
the piston area is 3.1416 by 5 by 5) ; and the area of the panel J (assumed to be 
24 by 48 inches in size) is 1,152 square inches, then the pressure per square 
inch of panel P would be : 
2200X78.54 
F ~ 1152 
or about 150 pounds. 
If a given pressure per square inch of panel is desired, the necessary gauge 
reading G can be calculated by the following formula : 
FX/ 
G —A-' 
the same values being used as in the case cited above, 
150X1152 
^~ 78.54 
or approximately 2,200 pounds. 
In the use of these formulas, it is an excellent plan to calculate the gauge 
reading required for different pressures and for panels of different size and to 
prepare the results in tables for the use of the press operator. 
