BULLETIN 
SWINGING DEVICE. 
The swinging device used on the different makes of dredge varies 
greatly. In some cases it consists of a circular, double-channel frame, 
firmly anchored to the deck, with several sheaves bolted at intervals 
in the circumference of the frame to carry the cable that travels over 
them in swinging the boom. In this fixed type of swinging device a 
large diameter of circle can be used. There is also the movable type 
of swinging circle. This generally consists of a solid iron circle 
mounted on a pivot. The heel of the boom is over the point of the 
pivot and the boom is braced to the circle. This type requires more 
deck room than does the first named type. The turntable may be 
placed on deck (PL I, fig. 1) or overhead (PL I, fig. 2), but the deck 
plan is generally used. 
Independent engines may be used for swinging the boom or power 
may be obtained from the main engine to drive the swinging drums. 
If this latter plan is followed two independent friction drums are 
attached to the bed plate of the engine and geared so as to be driven 
by it. If internal-combustion engines are used, independent friction 
drums are necessary for the various operations of the dredge. The 
common practice on large steam-operated machines is to have inde- 
pendent swinging engines. 
SPUDS. 
Spuds are heavy timber or steel members, the purpose of which is 
to hold the dredge in position while operating. One is placed on 
each side near the front and the third in the center line of the boat 
at the stern. Vertical spuds extend directly downward at the side 
of the hull and rest on the bottom of the excavated channel. They 
are used on deep-water dredges or for excavating large channels. 
For a dredge with a narrow hull bank spuds, which extend outward 
and rest on the ground surface, are preferable, since they give a large 
bearing surface and the footing is usually on solid ground. These 
are important features, as a longer boom and a larger bucket can then 
be used on a narrow hull. 
There are various patented types of bank spuds. One is the con- 
vertible bank-and-vertical power spud. This type can easily be 
changed from a bank into a vertical spud and is most convenient in 
crossing old channels, digging cut-offs, or making a double cut. 
Another type is the telescopic bank spud, so designed that the spud 
is either lengthened or shortened by means of a telescopic device. 
There are other styles of bank spuds, which, although they possibly 
do not have as wide a range as the telescopic type, can,' nevertheless, 
be operated successfully several feet above or below the water surface. 
Plate I, figure 1, shows a dipper dredge equipped with telescopic bank 
spuds. 
