Scientific American Supplement, No. 312, December 24, 1881 | Page 2

of one another, seems therefore more
suited for this kind of work. Other not inconsiderable advantages are
also secured by the adoption of the foundry crane type, the amount of
clear headway under the jib being much increased, and the difficulty
avoided of making a jib sixty feet long sufficiently stiff without undue
weight.
The principal dimensions of the crane are, total height of lift 46 feet,
radius variable from 25 feet minimum to 45 feet maximum, height from
rail to underside of jib 22 feet 2¾ inches, radius of tail to center of
boiler 22 feet, working load 15 tons, proof load 19 tons.
The general arrangement consists of a truck on which is fixed a post,
round which the crane revolves; the jib is supported midway by an
inclined strut, above which is placed the king-post; the strut is curved
round at the bottom and forms one piece with the side frames, which
are carried right back as a tail to support the boiler and balance weight.
The hoisting gear consists of a double system of chains 13/16 in. in
diameter placed side by side; each chain is anchored by an adjustable
screw to the end of the jib, and, passing round the traveling carriage

and down to the falling block, is taken along the jib over a sliding
pulley which leads it on to the grooved barrel, 3 ft. 9 in. in diameter. In
front of the barrel is placed an automatic winder which insures a proper
coiling of the chain in the grooves. The motive power is derived from
two cylinders 10 in. in diameter and 16 in. stroke, one being bolted to
each side frame; these cylinders, which are provided with link motion
and reversing gear, drive a steel crank shaft 2¾ in. in diameter; on this
shaft is a steel sliding pinion which drives the barrel by a double
purchase.
In the center of the crank-shaft is a large reversing friction clutch,
which drives, through miter gear, a vertical shaft placed just in front of
the post; from the latter the slewing, racking, and traveling motions are
obtained.
The crane can be turned through a complete circle by a pinion gearing
into a machine-moulded toothed ring bolted to the top of the truck; this
ring is 11 ft. 4-7/8 in. in diameter, and contains 172 teeth 2½ in pitch.
The slewing pinion is driven by intermediate gearing from the bottom
of the vertical shaft mentioned above. For the turning motion two
distinct sets of rollers are provided; these are carried by cross-girders
placed between the side frames; one set runs against a cast-iron roller
path bolted round the bottom of the post, and the other on the large
horizontal roller path seen in the engraving. The latter is 14 ft. in
diameter; it is built up of two deep curved channel irons with top and
bottom plates forming a circular box girder, on the top of which a
heavy flat rail is riveted, and the whole turned up in the lathe. The
racking and traveling motions are driven from the top end of the
vertical shaft; the racking gear consists of wire ropes attached to each
side of the traveling carriage and coiled round a large barrel, the outer
rope being brought over a pulley at the end of the jib. The rails for the
carriage rest on rolled joints bolted to the underside of jib. This
arrangement involves the use of an overhung traveling carriage, but
enables the jib to be of a stiff box section, the side stiffness being
further secured by wind ties.
The traveling motion is worked by a second vertical shaft, which passes

down the center of the post, and by means of a cross shaft is geared to
the front axle, from which four of the ground wheels are driven.
The post is octagonal, built up of plates ¾ in. thick; at the bottom end it
is secured to the girders of the truck, and at the top is shrunk on to a
large gudgeon 12 in. in diameter, which enters a casting fixed in the
back end of the jib; on the top of the gudgeon are two steel disks on
which an adjustable cap rests; by means of this and the ties to the tail
and the lower end of the strut a proportion of the weight can be brought
on to the post so as to relieve the roller path to any desired extent, and
enable the crane to be revolved easily.
The truck is 24 ft. long and 16 ft. 4½ in. wide; it is constructed of
longitudinal and transverse box girders 2 ft. 8 in. deep, and rests on two
axles 6 in. in diameter; round these axles swivel the cast-iron bogie
frames which carry