Transactions of the American Society of Civil Engineers, Vol. LXX, Dec. 1910 | Page 7

Gravity (=20 A) = 11.94. Friction = 4.70 |B |
16.64 | | Load: | Cars. | Locomotive.| Tender. | | Maximum[E] | 1,561 |
44.60 | 25.25 |C | 1,631 Minimum[F] | 1,031 | 60.50 | 34.50 |C | 1,126 | |
Traction (= B C ÷ 2,000 ) Maximum[E] |D | 13.60 Minimum[F] |D |
9.38 Weight on Drivers: | Locomotive.| Helper. | | Maximum[E] | 21.60
| 63.00 |E | 84.60 Minimum[F] | 47.00 | 72.00 |E | 119.00 | | Percentage
( = D ÷ E ). | | Maximum |F | 16.1 Minimum |F | 7.9
===================================================
=====================
FOOTNOTES:
[Footnote E: Giving maximum values of percentage, F.]
[Footnote F: Giving minimum values of percentage, F.]

BEVERLY S. RANDOLPH, M. AM. SOC. C. E. (by letter).--The
percentages given by Mr. Purdon would seem to indicate that the length
of the grades did not affect the loads in the cases cited, but these
percentages are so much below those shown in the table, for similar
distances, as to indicate some special conditions which the writer has
been unable to find in the text.
The use of the percentage of weight on drivers which is utilized in
traction as a measure of the efficiency of the locomotive, while,
probably, not applicable to individual machines, is sound for the
purposes of comparison of results to be obtained on various portions of
a line as far as affected by conditions of grade and alignment. It has the
advantage of disregarding questions of temperature, condition of track,
character of fuel, etc., which, being the same on all portions of the line,
naturally balance and do not affect the comparison. It is, of course,
simply a method of expressing the final efficiency of the various parts
of the locomotive, and, since it depends entirely on actual results
already accomplished, leaves no room for difference of opinion or

theoretical error.
The writer has always considered an "under-cylindered" locomotive as
a defective machine. All weight is a distinct debit, in the shape of wear
and tear of track and running gear, resistance due to gravity on grades,
interest on cost, etc. When this weight fails to earn a credit in the way
of tractive efficiency, it should not be present.
The statement relative to the performance of locomotives on "Hill C" is
interesting, especially in that it appears to have been immaterial
whether they made a dead start after stopping at the station or
approached the foot of the hill at 16 to 18 miles per hour. The
momentum would appear to be an insignificant factor.
It is gratifying to note that Mr. Trautwine has been able to brace up the
weak member of Table 1 so completely with his detailed data; also that
his other results strengthen the conclusions reached in the paper.
FOOTNOTES:
[Footnote A: "The Economic Theory of Railway Location," 1887
edition, p. 502.]
[Footnote B: Transactions, Am. Soc. C. E., Vol. L, p. 1.]
[Footnote C: "Nearly 200 tons exclusive of eng. & ten." (Vol. III, p.
176-1/10.)]
[Footnote D: American Railway Engineering and Maintenance of Way
Association, Bulletin 84, February, 1907, p. 99.]

End of the Project Gutenberg EBook of Transactions of the American
Society of Civil Engineers, Vol. LXX, Dec. 1910, by Beverly S.
Randolph
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