Brake Tests

124 275. The braking power was equalized on all shoes, but the brake hangers were given approximately the same inclination as with clasp brake No. 1. This again resulted in the inside brake shoe falling away from the wheel and taking all the available slack, causing the outside shoes to drag on the wheel. Clasp Brake No. 3. 276. In this type of brake rigging, Figs. 6, 7 and 71, the members were so located that when the brake was applied, all the rods pulled perpendicularly to their respective levers and the pull rods rested on rollers, reducing the friction to a minimum. The shoes were hung as high as conditions would permit being 24 inches below the center line of the axle, the brake heads were pin connected to the hanger levers, enabling the shoe to adjust itself readily to the wheel. When first applied, the cylinder end of the main brake rod was higher than the other-end, which resulted in an undesirable lifting of the radius bar in the center sill. After a few tests had been made this condition was remedied and the rigging arranged so as to move properly without interference. 277. This rigging also differed from the first and second designs in having a radius bar connecting the body pull rods to the top of the live truck levers. 278. There is a possibility of this radius bar connection shortening the piston travel during brake applications on curves. Definite infor- mation was not obtained on this latter feature during the tests. Tests Made AND RESULTS. 279. The standard (single shoe) brake rigging and the first and second designs of clasp brake rigging, already described, were tested under various conditions of speed, air brake equipment and braking power, using the complete train of twelve (12) cars and locomotive, and also in twelve (12) car breakaway stops. The second design of clasp brake rigging was also tried out in single car breakaway tests and the third design of clasp brake rigging in single car breakaway tests only, there being but one of the test cars equipped with this type of rigging. Therefore, in comparing the different types of rigging it will be necessary to make the comparisions accordingly so far as the actual stops are concerned, although a method has been developed whereby the probable stop of a complete train equipped with the No. 3 design of clasp brake can be computed with what is believed to be reasonable accuracy. This is explained in Par. 406. 280. On account of the many different conditions of air brake equipment, per cent, of braking power, and manipulation used with the different types of brake rigging, it is necessary to choose arbitrarily some representative combination of these factors and compare the dif- ferent riggings all on the same basis. For this purpose the best avail- able records are those of the so-called check runs, namely, emergency