The Locomotive - Lighthouse Survival Blog

1901.] THE LOCOMOTIVE. i {J
tice requires ; because we have assumed, in deducing .
the formula, that the pin rests
against the brace-jaws at the outer edges of the jaws. When the holes in the jaws are
straight, however, and fair with the hole in the lug, there is a tendency on the part of the
brace pin to yield a littLe, and take the form shown in Fig. 4; and this action will bring
the bearing points of the jaws nearer together, and will, at the same time, tend to make
the lug touch the pin at its two outer edges only. The load being thrown upon the pin
in this new manner, it is not difficult to show that the bending stress on the pin is ma-
terially less than it is when the load falls upon it as shown in Fig. 3. These various
uncertainties can hardly be avoided, in computing the strength of a brace pin ; but if
the pin diameter be calculated in accordance with the formula we have given, we shall
certainly obtain a result that is large enough for safety. If the design and workmun
Fig. 5. — A Brace Pin which Failed Partly by Shearing, and
Partly by Bending.
ship of the pin and its fastenings are good, some reduction in the diameter given by the
bending formula may be allowed. How much reduction it will be safe to make, must be
left to the judgment of the individual designer or inspector, who is familiar with the
facts in each special case. But it will not do, under any circumstances, to allow the
brace pin to be smaller in diameter than our previous rule for calculating its resistance
to shearing would indicate. We may, therefore, say, that the way to compute the
diameter of a brace pin is to find the diameter (I) on the supposition that the pin fails
by shearing, and then (2) on the supposition that it fails by bending; and we must take
for the diameter of the pin a value which is at least as great as the diameter indicated
by the rule for finding its shearing resistance, but which may be somewhat smaller
than the rule for finding its resistance to bending stresses would call for, provided the
design and workmanship of the pin and its fastenings are satisfactory in all respects.
In the special problem submitted for our consideration, and which is illustrated in
Figs. 1 and 2, we, should say that a pin \% in. in diameter would be ample.
Boiler Explosions.
May, 1901.
(134.)— On April 29th a boiler exploded in C. L. Reaves' machine shop, at Muskogee,
I. T. John Harlow was killed, and Charles Nasey was fatally injured. The
explosion tore one end of the shop out, and the shock was felt all over the city.
[Received too late for insertion in the regular April list. — Editor.]
(135.)_ A boiler exploded, on May 1st, at Staufordville, near Poughkeepsie, N. Y.,
in the saw-mill and blacksmith shop of < Icorge and Charles Beilke. Some signs of leak-