Brake Tests

243 These tests were made under two conditions of wheel load as follows:— (a) Six (6) rings in the fly wheel, equivalent to 15 900 lb. wheel load. This corresponds to a four wheel truck car weighing 127 200 lb. with one brake shoe per wheel. NII K. F © B L o / H Pl C 80 Fig. 148. BRAKE SHOE TESTING MACHINE. At A is shown the main lever holding the brake shoe B. An adjustable weight D is carried on the lever C. The rod K transmits the pull of the brake shoe to the weighing mechanism at L. (b) Two (2) rings in the fly wheel equivalent to 7 220 lb. wheel load. This corresponds to a four wheel truck car weighing 115 600 lb. with brake shoes on each side of the wheel. It will be noted that the wheel load in this case was slightly less than half of that in the first case, but the difference could not be eliminated with the fly wheel adjustment provided. D.—Necessary controller and electric devices for governing the speed of the motor and test wheel. B.— A head for holding a brake shoe with a system of levers and adjustable weights for applying any desired pressure to the brake shoe. F.—An air cylinder with brake valve for holding the shoe away from the wheel and bringing same into contact with the wheel when desired and at any rate required. G.—An Emery Dynamometer and Chronograph for graphically recording (n) Pull of brake shoes. (b) Speed. (c) Distance traveled or length of stop.