BRAKE CYLINDERS 



343 



expander ring and clean the piston-packing leather by rubbing 

 it with clean oily waste. If the leather is worn out or imper- 

 fect in any way, replace it with a new one. The flesh side of 

 the leather should be next to the cylinder walls, because it 

 wears better and is not so apt to leak when put in this way. 

 See that the follower head is in good condition and that the 

 bolts are tight; also, that the piston rod is tight in the piston 

 head. Soften the packing leather by working it with grease; 

 put some grease in the expander-ring groove and replace the 

 piston in the cylinder. To enter the piston properly, start it 

 in edgewise, having the rod extended downwards at 45 with 

 the cylinder; then slowly raise the piston while shoving the 

 packing leather into the cylinder with the fingers. When it 

 is entered, shove it back to position and turn the piston rod so 

 that the expander-ring joint will be at the side of the cylin- 

 der and away from the leakage groove; secure the non- 

 pressure head. Also, see that the bolts that secure the brake 

 cylinder to the car are tight. The brake may then be properly 

 connected up, tested, and any 

 rules and regulations regarding 

 records, etc. complied with. 



CROSS-SECTIONAL AREA 

 OF BRAKE CYLINDERS 



CROSS-SECTIONAL 

 AREA OF CYLINDERS 



The accompanying table 

 gives the cross-sectional areas 

 for the standard sizes of brake 

 cylinders. The calculation of 

 the capacity of brake cylinders 

 and reservoirs may be made by 

 the following rule: 



Rule. To find the cross-sectional area of a cylinder, in square 

 inches, multiply the internal diameter, in inches, by the diameter 

 and by .7854. 



EXAMPLE. What is the cross-sectional area of a cylinder 

 whose internal diameter is 10 in.? 



SOLUTION. The area equals 10 X 10 X. 7854 = 78.54 sq in., 

 call it 78* sq. in. 



