A widely accepted shape for hooks of this character used on cranes is shown in Fig. 71. The shape and formulas for the dimensions are given by Henry R. Towne in his:

## Table I. Sizes Of Hoisting Hooks

 Item Symbol Sizes Load (tons) T i 1 1/2 l 1 1/2 2 3 4 5 6 8 10 Stock (inches) A i 11/16 i 1 1/16 1 1/4 1 3/8 1 3/4 2 2i 2 1/2 2 7/8 31

## "Treatise On Cranes"

The size of stock required for a hook to carry any particular load is given in Table 1; the load for which the hook is designed being given in the upper line, while the lower line gives the size of the stock to be used in making the hook.

T = working load (tons of 2,000 pounds) A = diameter (inches) of round stock used to form hook The other dimensions of the hook are found by the following formulas, all of the dimensions being given in inches:

Fig. 71. Details of Hoisting Hook.

B= .8 A C=1.2 A D = .5 T+1.25 E = .64 T+1.6 F= .33 T+ .85 . G- .75 D 0= .363 T + .66 Q= .64 T+1.6.

H=1.08 A I=1.33 A J=1.2 A K=1.13 A L =1.05 A M = .5 A N = .85 B-.16 U= .866 A.

### Illustrative Example

To illustrate the use of the table, suppose it be required to make a hook to raise a load of 500 pounds or onequarter of a ton. In the line marked T is found the load 1/4; directly below it are the figures 11/16, showing the size of stock to be used. The dimensions of the hook are found as follows:

D-.5 xl+1.25 = l 3/8 inches.

E=.64X 1/4+1.6 -If inches (about) Etc.

1=1.33 A -1.33 X 11/16=.915, or about 29/33 inch.

When reducing the decimals the dimensions which have to do only with the bending of the hook, i.e., the opening, length, length of point, etc., may be taken to the nearest 16th, but the dimensions through the body of the hook or stock should be reduced to the nearest 32nd on small hooks. The completed dimensions of the hook in question, of 500-pound capacity, would be as follows:

D= 1 3/5 inches E = 1 3/4 inches F= 15/16inch G=l inch O= 3/4 inch Q = 1 3/4 inches H= 3/4 inch.

I=29/32 inch J= 13/16 inch K=25/32 inch L = 23/32 inch M= 11/32 inch U=16/33 inch.