Brake Tests

68 149. With regard to the latter feature it is of interest to note that several cases no blow-down at all was obtained (see Figs. 58, 59, 60 and 61, tender brake cylinder indicator cards). This was due to a lack of sensitiveness in the working parts of the by-pass valve. It is interesting to note, however, that a comparison of the results obtained when the by-pass valve blow-down feature operated properly, and when it did not, shows that under the conditions of this test the blow-down feature appeared to have but little effect. The results were substantially the same whether or not the high locomotive pressure was blown down toward the end of the stop. 150. The device itself and its installation were of a temporary character, for the purpose of obtaining immediate results in connection with this series of tests, and will not be described in detail. If such a device were to be used material modification would be made in the construction of the apparatus to insure its performing whatever func- tions were considered to be desirable and to enable it to be conveniently used as an integral part of the standard ET brake equipment. ELECTRIC SIGNAL SYSTEM. 151. When the test train was being equipped, advantage was taken of the opportunity to install a circuit and the necessary details which would permit the many advantages of an electro-pneumatic signal system to be demonstrated. The wiring required is shown in Fig. 27. The standard car discharge valve (Fig. 40) was furnished with electric contacts for the purpose of this test. A plain magnet valve was used on the locomotive in addition to the standard signal valve, arranged so that either the electro-pneumatic or the pneumatic signal system could be used at will. 152. While no records were made of tests of the electro-pneumatic signal system its performance when used in the ordinary course of the handling of the test train was such as to demonstrate the possibilities of this form of signal system.