Speed in
Miles per
Hour.
Distance in
Feet.
Time in
Seconds.
Equivalent Distance
at 20 m. and 40.
19½ 186  9¾ 196 · ·
19¼ 215 11 233 · ·
36½ 588 17 · · 693

The remarkable shortness of these stops is the more evident when they are compared with the best results obtained in 1886, as shown in Table II.

Table II.—Stops of a Train of Fifty Empty Cars, 1886Automatic Air-Brakes.

Speed in
Miles.
Distance in
Feet.
Time in
Seconds.
Equivalent Distance
at 20 m. and 40.
23.5 424 17½ 307 · ·
20.3 354 16 340 · ·
40  922 22½ · · 922
40  927 22¾ · · 927

The time that elapsed between the application of the brakes on the engine and on the fiftieth vehicle was almost twice as great in 1886 as in 1887, being in the latter tests only five to six seconds, and in 1887 the stops were made in less than two-thirds the distance required in 1886. Still, violent shocks were caused by the rear vehicles running against those in front, before the brakes on the former were applied with sufficient force to hold them, and these shocks were so severe as to make the use of the brakes in practice impossible on long trains. When the triple-valves were actuated electrically, however, the stops were still further improved, as shown in Table III.

Table III.—Stops of a Train of Fifty Empty Cars— Electric Application of Air-Brakes.

Speed in
Miles.
Distance in
Feet.
Time in
Seconds.
Equivalent Distance
at 20 m. and 40.
21½ 160  7 139 · ·
23  183  8 138 · ·
38  475 14½ · · 519
36½ 460 14 · · 545

Although the same levers, shoes, rods and other connexions were used, there were no shocks in the fiftieth car of the train on any stop, whether on the level or on a gradient. The committee in charge reported that the best type of brake for long freight trains was one operated by air, in which the valves were actuated by electricity, but they expressed doubt of the practicability of using electricity on freight trains. The Westinghouse Company then proceeded to quicken the action of the triple-valve, operated by air only, so that stops with fifty-car trains could be made without shock, and without electrically operated valves; and they were so successful in this respect that, towards the end of the same year, 1887, with a train of fifty vehicles, stops were made without shock, fully equalling in quickness and shortness of distance run any that had been made at the trials by the electrically operated brakes.

In 1889 some further tests were made by Sir Douglas Galton with the automatic vacuum-brake, on a practically level portion of the Manchester, Sheffield & Lincolnshire railway (now the Great Central). The train was composed of an engine, tender and forty carriages, the total length over buffers being 1464 ft., and the total weight 574 tons, of which 423 tons were braked. At a speed of about 32 m. an hour this train was brought to a standstill in twelve seconds after the application of the brakes, in a distance of 342 ft.