Two centuries of shipbuilding by the Scotts at Greenock

Joggling Plates and Angles : Hydraulic Riveting. 99
special hydraulic tools are provided to carry out this work.
The firm were also early in adopting the practice of
joggling frames, deck beams, etc. The frames and beams
are joggled when cold, to suit each alternate inner strake
of plating, in a special design of hydraulic press, of which
there are several in the works. This tool, illustrated on
Plate XLL, adjoining page 95, carries dies on the ram-head
and on the anvil, to form between them the obverse and
reverse sides of the dent or joggle desired. Movable
centre-pieces on the ram-head and anvil are traversed in all
directions by screw thread to suit the position and width of
the joggled part, and a gauge shows variations of 0.1 in. in
the position of the joggled part of the frame. A 2 ft.
length of angle can be joggled at each stroke. The machines
are by Messrs. Hugh Smith and Co., Limited, Glasgow.
The same machine joggles the lap or edge of a shell,
inner bottom, or deckplate in a similar way. The whole
length of the frame or plate can thus be worked in a very
short time. A powerful jib crane, of 16 ft. radius, assists
materially in the rapidity of the work turned out by these
tools. The only slips required are at the ends of the
vessel, where the bevel of the frames precludes the use of
joggling. A special electrically-driven hammer is used for
forming these taper slips.
The angles, etc., to form the frames are assembled at
the head of the building-berth, and when lying on skids
are riveted to form the double bottom, frames and margin
plates. Hydraulic riveters are used wherever possible.
There are about a score of these at work in the ship-
building yard, with cylinders from 8 in. to 10^ in. in
diameter, a stroke of 1\ in., and a gap of 55 in., so that
heavy work can be done. Some of them are specially
designed for keel work, for closing rivets in beams, and
for difficult parts.
The frames thus riveted are conveyed down the berth