MECHANICS 



273 



COEFFICIENTS OF FRICTION, ANGLES OF REPOSE, 

 AND WEIGHTS OF EARTHS 



Material 



Coefficient 

 of Friction 



Angle of 

 Repose 

 Degrees 



Weight 

 Pounds per 

 Cubic Foot 



Mixed earth, dry 



Mixed earth, damp 



Mixed earth, wet 



Sand, dry 



Sand, wet 



Loam, dry 



Loam, wet 



Clay, dry 



Clay, wet 



.70 

 .80 

 .40 

 .65 

 .05 

 .70 

 .50 

 1.00 

 .30 



35 

 39 

 22 

 33 

 3 



35 

 27 

 45 

 17 



95 



115 



115 



110 



125 



75 to 100 

 90 to 120 



100 



125 



COEFFICIENTS AND ANGLES OF FRICTION FOR 

 MISCELLANEOUS MATERIALS 



Materials 



Coefficient Angle 



of Friction of Friction 



Cast iron on cast iron .15 



Cast iron on brass .15 



Cast iron on oak .49 



Wrought iron on wrought iron .... .14 



Wrought iron on cast iron .19 



Wrought iron on brass .17 



Wrought iron on mahogany .18 



Wrought iron on oak .62 



Steel on cast iron .20 



Steel on brass .15 



Steel on ice .014 



Yellow copper on cast iron .19 



Yellow copper on oak .62 



Brass on cast iron .22 



Brass on brass .20 



Brass on wrought iron .16 



Bronze on cast iron .21 



Bronze on wrought iron .16 



Bronze on bronze .20 



Oak on oak .48 



Oak on elm .25 



Oak on cast iron .37 



Leather on oak .33 



Leather belt on oak drum .27 



Leather belt on cast iron .56 



Leather packing .56 



)eg. Min. 



8 32 



8 32 

 26 6 



7 58 

 10 46 



9 39 



10 12 

 31 47 



11 19 



8 32 

 48 



10 46 

 31 48 



12 25 



11 19 



9 6 

 11 52 



9 5 



11 19 



25 38 



14 3 

 20 19 

 18 16 



15 7 

 29 15 

 29 15 



