102 



Soft cast-iron shoe. 

 Slow speed. 



Pressure increasinj;- Iroin 2,100 pounds to lOJUO pounds. 

 Coefficient of friction docreasini;- from 37 per cent, to 20 per 

 cent. 

 Soft cast-iron slioe. 

 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 deci'easing- from 33 per cent, to 

 18 per cent. 

 Hard cast-iron shoe. 

 High 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 slioes decreases with increase 

 of initial speed. The values are approximately as follows: 

 Soft cast-iron shoe. 

 Light pressure. 



Speed increasing fi'om 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 horn-. 

 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. 



