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