Brake Tests
År: 1913
Forlag: Pensylvania Railroad Company
Sted: Altoona, Penna.
Sider: 401
A Report Of A Series Of Road Tests Of Brakes On Passanger Equipment Cars Made At Absecon, New Jersey, In 1913
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234
CHAPTER VII.
BRAKE SHOES.
Road Tests.
437. The condition of the material in the brake shoes, the manner
in which they are adjusted to fit the wheel, and the bearing which the
shoes have upon the wheel will materially influence the length of stop,
having the greatest effect at the higher speeds. These agencies,
although previously observed and recognized in a theoretical way, had
never been so forcibly impressed upon observers as during the present
series of tests and the information gained from the special attention
given the performance of the brake shoes in the tests has devéloped
some noteworthy facts in regard to them.
438. Prior to starting the tests it was arranged to have the brake
shoes made from special heats and to be as near as possible to the normal
composition of our standard cast iron shoes in order that the variation
in brake shoes might not affect comparisons of air brake equipment
and the brake rigging.
439. Before applying these shoes to the test train they were
broken in on other trains to wear off the face surface or slight chill
incident to foundry practice. When so broken in, with an average of
1inch of thickness removed from the face, Brinell hardness readings of
the surface were taken and the shoes grouped according to hardness
numbers. The results of this preliminary work, showing the grouping
as to the number of shoes obtained from two heats in range of hardness
and the chemical analysis are shown in the following tables:
Range of Hardness and Number of Shoes Under Each Group.
First Heat.
Range of Brinell Hardness Numbers 160 to 170 170 to 180 180 to 185 ♦ 185 to 190 * 190 to 195 * 195 to 200 ♦ 200 to 205 205 to 210 ♦ 210 to 215 215 to 220 220 to 230 230 to 240 240 to 300 i Total |
Number of Shoes 6 29 39 27 54 73 99 102 95 31 21 8 8 592
Second Heat.
Number of Shoes 1 136 474 38 649
* Shoes placed on test train.
ANALYSIS OF Shoe.
Per Cent. Per Cent.
Graphitic carbon........2.71 Phosphorus..........0.53
Combined carbon.......0.69 Silicon.............0.92
Manganese...............0.46 Sulphur..............0.135