Brake Tests

129 but after making due allowance in this manner, the stops with the No. 3 clasp brake are still materially shorter than corresponding stops with the No. 2 clasp brake. 287. To sum up, therefore, the relative performance of the several different types of rigging tested on the basis of stopping distance alone, would on the whole be arranged in the following order: Best, the No. 3 clasp brake next, the No. 2 clasp brake next, the No. 1 clasp brake and, lastly, the standard single shoe brake. Brake: Rigging Efficiency. 288. The device as shown in Figs. 72 to 75 was used to measure the efficiencies of the various types of brake rigging tested. The prin- Fig. 72. BRAKE SHOE PRESSURE MEASURING DEVICE. This shows how the device was applied to the single shoe brake. ciple on which this device is based was the same for all riggings, modi- fications being necessary to make its application suitable to the various types of truck and brake rigging arrangements used. 289. A soft steel plate of known hardness and uniform structure was used to record the pressure with which a hardened steel ball was pressed against it, the depth of the impression being proportional to the force. 290. The device holding the ball and plate was located in the brake rigging as near the shoe as possible so that the force transmitted by the brake rigging passed through the ball to the plate on its way