Brake Tests

109 STANDING TESTS. Improvement in Brake Release Resulting from the Use of UC Equipment Mixed with PM Equipment. 234. Test No. 679 (Fig. 64), already referred to (Par. 226), showed the greater sensitiveness of the UC equipment to release under conditions which resulted in the PM equipment failing to release. The standing tests (670 and 671) were made to further demonstrate that the UC equipment in the place of PM equipment on some of the cars of a train would tend to cause such PM equipments as were used to release more certainly than if the UC equipment were not used. 235. A 14-car train was made up as follows: Six PM equipments at the head end followed by three UC equipments, then three PM and on the rear end two Pullman chair cars having the PM equipment. A ten pound brake pipe reduction was made by the engineman and the brake valve handle placed in running position after exhaust at the brake valve had ceased. Under these conditions (test 670) the PM brake on car five failed to release although all the other cars in the train released satisfactorily. It follows, therefore, that to insure a release of this brake some improvement in the condition existing when re- leasing was required. 236. To show that the use of the UC equipment brought about this necessary improvement in conditions, test 671 was made with all circumstances as mentioned above, except that the UC equipment instead of the PM equipment as in test 670, was cut in on cars 1, 2 and 3. In this test the brake on car five released promptly, as did all the others. 237. This showed that the presence of the three UC equipment cars at the head end of the train permitted a sufficiently faster build-up in brake pipe pressure to insure the release of the brake on car five which did not release when the rise in brake pipe pressure was not so favored. In other words, the presence of the UC equipment mixed with the PM equipment in the same train will result in an improvement in the release action of all the brakes in proportion to the number of UC equipments used. DETECTION OF CLOSED ANGLE COCK WHEN OPERATING Electrically. 238. In order to determine what would result from the closing of a brake pipe angle cock when using the electro-pneumatic control of the brakes, the following test (669) was made:— With the 12-car train charged, the angle cock between the fourth and fifth cars was closed and an emergency application was made by opening the conductor’s valve on the fifth car. The emergency appli- cation was transmitted electrically through all cars in the train, the