The Locomotive - Lighthouse Survival Blog

100 THE LOCOMOTIVE. [July,
rear half of the crown-sheet one part turned up, and the remaining portion turned down
to the side of the fire-box. There was no indication of low water. The safety-valve
was so w y edged into the debris that we could not get at it for examination. Engineer
Weimer stated that there was plenty of water in the boiler, and that the steam-gauge
indicated 80 pounds.
It will be seen from Fig. 2 that flat Z-braces were used on the crown-sheet. This
form of brace is inherently weak, and should never be used for such purposes. The
solid crow-foot brace is superior to it in every way. In Fig. 4 we present two views of
the Z-brace, which will illustrate the cause of its weakness. The left-hand view shows
the brace as first put in, while the right-hand view shows what happens to the brace
when a pull comes on it. The ends are drawn away from the sheets, and the brace
straightens out and allows the crown-sheet to bulge outwards. In most cases this de-
flection of the crown-sheet will not be sufficient to cause an immediate fracture; but as
the pressure in the boiler varies the brace will bend back and forth, and in the course of
time it is almost certain to crystallize and fracture across the line of greatest bending.
This action is well illustrated by the common process of breaking a wire by repeatedly
bending it back and forth with the hands. The action in the case of the Z-brace is
precisely the same, and that is why we say that this form of brace is inherently weak.
Inspectors' Report.
May, 1894.
During this month our inspectors made 8,142 inspection trips, visited 15,966 boilers,
inspected 6,893 both internally and externally, and subjected 735 to hydrostatic press-
ure. The whole number of defects reported reached 11,613, of which 1,123 were considered
dangerous; 35 boilers were regarded unsafe for f-irther use. Our usual summary
is given below
:
Nature of Defects.
Cases of deposit of sediment, -
Cases of incrustation and scale
Cases of internal grooving, -
...
Cases of internal corrosion, -
-----
Cases of external corrosion, -
Broken and loose braces and stays, -
Settings defective,
Furnaces out of shape,
Fractured plates, -
Burned plates, -
Blistered plates, -
-
-
- - ...
Cases of defective riveting, - - - -
Defective heads,
Serious leakage around tube ends, -
-
...
-----
Serious leakage at seams, -
Defective water-gauges,
Defective blow-offs,
Cases of deficiency of water, - - - -
Safety-valves overloaded, -
Whole Number.