MEMBERS IN TENSION. 573 



The size of pin required by shear and moment can be obtained from the lower part of Table 

 93, and is a 2 in. pin if the forks are closed, or a 3 in. pin if the forks are used straight. The 

 thickness of connection plate required by bearing when a 2 in. pin is used, is 48,000 * (2.00 X 24,- 

 ooo) i.oo in., if a 3 in. pin is used the plate must be 48,000 -5- (3.00 X 24,000) 0.66 in. 



The weight of the bar and two clevises is estimated as follows: 



The length of the rod, allowing for clearance, etc., must be reduced by A % in. 8 % 

 7/4 in. (Table 93) at each end, or a total of 2 X 7H = i' 3"- The diameter of upset for a 

 l% in. square bar is 2}^ in., which requires 4^ in. material to make each upset (Table 89), or 9 

 in. for both upsets. 



The total length and weight of 1% in. square bar is: 



c. to c. of pins, less i' 3", = 10' 9" of i% in. square bar, @ 10.41 Ib. per ft. (Table 6) = 111.9 Ib. 



Material for 2 upsets = o' 9" of i% in. square bar, @ 10.41 Ib. per ft. (Table 6) = 7.8 Ib. 



Two No. 6 clevises @ 26 Ib. (Table 93) = 52.0 Ib. 



Total Length = u' 6" Total Weight = 171.7 Ib. 



Eye-Bar. Select an eye-bar to carry a tensile stress of 190,000 Ib., with an 8 in. pin at one 

 end and a 6^ in. pin at the other end, the length center to center of pins being 25' o". 



References. 33, p. 57; 106, p. 62; 162, p. 66; 37, p. 141; 92, p. 144; 141, p. 145; 

 171, p. 147; 14, p. 206; 36, p. 206; "Minimum Bar," p. 207; 83, p. 207; 15, p. 209; 

 36, p. 210; 83, p. 213; 136, p. 216; 162, p. 218. 



Solution. Using an allowable unit stress of /< = 16,000 Ib. per sq. in., the area required is, 



P 190,000 



A = -r = -^ = 11.87 sq. in - 



ft 16,000 



A bar 8 in. X i% in. has an area of 12.00 sq. in. (Table i). From Table 91, the maximum thick- 

 ness allowed for an 8 in. bar on a 6% in. pin is 2 in., and the minimum is I in. (The value 6^ 

 in. does not appear in the table but it is less than 7 in., which is the maximum pin which can be 

 used if the die referred to is used.) For an 8 in. pin the maximum thickness is 2 in. and the 

 minimum I % in. The bar selected satisfies these requirements as to thickness. 



The extra length of bar required to form a head for a 6)^ in. pin (die for 7 in. pin) is 2' 8" for 

 ordering the bar, and 2' 3" for estimating the weight, and for an 8 in. pin 3' o" and 2' 6", respec- 

 tively (Table 91). 



. The total length and weight of eye-bar is therefore: 



c. to c. of pins = 25' o" of 8 in. X 1 1 A in. bar. @ 40.8 Ib. per ft. (Table 2) = 1020.0 Ib. 



Eye for 6H in. pin = 2' 3" of 8 in. X I > in. bar, @ 40.8 Ib. per ft. = gi.Slb. 



Eye for 8 in. pin = 2' 6" of 8 in. X l^ in. bar, @ 40.8 Ib. per ft. = 102.0 Ib. 



Total Length = 29' 9" Total Gross Weight = 1213.8 Ib. 



The weight which must be deducted for pin holes (Table 6) is, 



Pin hole for 6 1 A in. pin is 1.5 -4- 12 X 112.8 = 14.1 Ib. 



Pin hole for 8 in. pin is 1.5 -5- 12 X 171.0 = 21.4 Ib. 



Total weight to be deducted =35-5 Ib. 



The net weight of the eye-bar is then 1213.8 35.5 = 1178.3 Ib. 



For the design of an eye-bar subject to flexure due to its own weight, see "Combined Flexure 

 and Direct Stress" in this chapter. 



Angle in Tension. Select an angle to carry a tensile stress of 40,000 Ib., using % in. rivets. 



References 33, p. 57; 39, p. 57; 40, p. 58; 79, p. 60; 83, p. 60; 84, p. 60; 85, 

 p. 60; 89, p. 61; 104, p. 61; 22, p. 105; 37, p. 141; 43, p. 141; 60, p. 142; 79, p. 144; 

 80, p. 144; 14, p. 206; 26, p. 206; 45, p. 206; "Fastening Angles," p. 207; 15, p. 209; 

 26, p. 210; 38, p. 210; 57, p. 210; 74, p. 212; p. 219; p. 223; 232, p. 363; 8, p. 379. 



