102 



Soft cast-iron shoe. 

 Slow speed. 



Pressure increasing from 2,700 pounds to 10,700 pounds. 

 Coefficient of friction decreasing from 37 per cent, to 20 per 

 cent. 

 Soft cast-iron sboe. 

 High speed. 



Pressure increasing from 2,700 pounds to 10,700 pounds. 

 Coefficient of friction decreasing from 25 per cent, to 15 

 per cent. 

 Hard cast-iron shoe. 

 Slow speed. 



Pressure increasing from 2,700 pounds to 10,700 pounds. 

 Coefficient of friction decreasing from 33 per cent, to 

 18 per cent. 

 Hard east-iron shoe. 

 Higli speed. 



Pressure increasing from 2,700 pounds to 10,700 pounds. 

 Coefficient of friction decreasing from 17 per cent, to 12 

 per cent. 

 2. The coefficient of friction of brake shoes decreases with increase 

 of initial speed. The values are approximately as follows: 

 Soft cast-iron shoe. 

 Light pressure. 



Speed increasing from 10 to 05 miles per hour. 

 Coefficient of friction decreasing from 37 per cent, to 25 pei 

 cent. 

 Soft cast-iron shoe. 

 Heavy pressure. 



Speed increasing from 10 to 65 miles per hour. 

 Coefficient of friction decreasing from 27 per cent, to 20 per 

 cent. 

 Hard cast-iron shoe. 

 Light pressure. 



Speed increasing from 10 to 65 miles per hour. 

 Coefficient of friction decreasing from 33 per cent, to 20 per 

 cent. 



