STRENGTH OF BEAMS 



59 



127. The yoke of a hydraulic press used for forcing gears on shafts is of the 

 form and dimensions shown in Fig. 56. The yoke is ^horizontal, with groove up, 



so that the shaft to be fitted lies in the 

 groove, as shown in plan in the figure. 

 The ram is 32 in. in diameter and under 

 a water pressure of 250 lb./in. 2 Find 

 the dangerous section of the yoke and 

 the maximum stress at this section. 



128. A 10-in. I-bar weighing 40 Ib./ft. 

 is supported on two trestles 15 ft. apart. 

 A chain block carrying a 1-ton load 

 hangs at the center of the beam. Find 



the factor of safety. 



129. The hydraulic punch shown in 

 FIG. 58 Fig- 57 is designed to punch a f-in. hole 



in a f-in plate. The dimensions of the 



dangerous section AB are as given in the figure. Find the maximum stress at 

 this section. 



130. The load on a car axle is 8 tons, equally distributed between the two 

 wheels (Fig. 58). The axle is of cast steel. Find its diameter for a factor of 

 safety of 15. 



131. The floor of an ordinary dwelling is 

 assumed to carry a load of 50 Ib./ft. 2 and is 

 supported by wooden joists 2 in. by 10 in. in 

 section, spaced 16 in. apart on centers. Find 

 the greatest allowable span for a factor of 

 safety of 10. 



132. An engine shaft of machinery steel 

 rests in bearings 6 ft. apart between centers 



and carries a 12-ton flywheel midway between p IG 59 



the bearings. Find the required size of shaft. 



133. A cast-iron flange coupling is connected with ten wrought-iron bolts. 

 Distance from axis of each bolt to axis of shaft is 6 in. Total torque (twisting 

 moment) transmitted is 12,000 ft.-lb. If the flanges are accidentally separated 2 in. 

 and the bolts are a drive fit, find the bending stress produced in each bolt. 



134. In the carriage clamp shown in Fig. 59 the screw is of wrought iron, | in. 

 .diameter, square thread, 5 threads per inch, and the casting has the dimensions 



given in the figure. Find what 

 load on the screw will cause fail- 

 ure by shearing the threads, and 

 find the maximum stress in the 

 casting under this load, due to 

 combined bending and tension. 

 135. In the joiner's clamp 



shown in Fig. 60 the bar is of carbon steel, l^in. x in., tensile strength 

 70,000 lb./in. 2 , and the screw is steel, fin. diameter, square threads, 5 threads 

 to the inch. Find the dimensions of the cast-iron handle so that it shall be light 

 enough to act as the breaking piece, 



FIG. 60 



