Brake Tests

168 (e) Greater brake pipe reduction in service than was desired. (/) Trip not properly set, resulting in delayed brake application. C.—Tests made with less than twelve cars. These have either been excluded or averaged in themselves. D.—Tests intended for one group which, due to improper cutting in of equipment on cars, gave operation of the air brake equipment similar to some other series. E.—Speeds differing considerably from the nominal. F.—Brake shoes not worn to a good bearing. For this reason most of the early tests on all types of brakes were excluded as well as many of the later tests with the single shoe brake during which many new shoes were being applied, as shown on the graphical log. G.—Excessive wheel sliding. An arbitrary limit was chosen of 3,000 feet or over of total wheel sliding on a twelve car breakaway or train stop, and 250 feet on a single car test. H.—Car stops affected by locomotive in breakaway tests. In some cases these have not been excluded but attention is called to those tests on which this condition was present, usually those made at the lower braking powers. I .—Equipment variables. This includes: (a) Locomotive used, No. 3394—K2a or No. 5223—K2Bll. (b) Nominal tender braking power. (c) Brake cylinder levers (80 or 90 per cent.). (d) Condition of lever pins and compression rod guides. 380. A test containing two or more equipment variables not found in the other tests of the series was excluded from the average. 381. It will be noted in the summary of tests that all tests of a series in which the same equipment variables are present have been averaged separately, as well as being included in the general averages. 382. The average equated stop was calculated by equating to the nominal speed the average actual stop from the average actual speed. 383. In some of the train and twelve car breakaway tests the first car in the train had brake heads and shoes unlike the other cars of the train. This variable in itself was not considered of sufficient weight to exclude the test from the average of a series of train tests. In tests of this car alone separate averages were made for these variables. 384. In the breakaway tests separate averages are shown for the locomotive stops, except in cases when the locomotive brakes were intentionally released or prevented from applying with the car brakes to avoid affecting the stop of the cars.