dangerous equipment found in R-l division. All
structural shops, regardless of the type of ship or shore
facility you will be assigned to, have some or all of the
equipment discussed in this chapter. It is important that
you have a general understanding and knowledge of
how to use these different types of equipment. It is not
the intent of this training manual to make you an expert
on the use and operation of the different machines. You
should, however, be able to identify the types of
machinery, the general operation, and safety
precautions associated with this equipment.
The machinery found in most structural shops can
be classified into two basic categories: cutting
machines and forming machines.
CUTTING MACHINERY
This section will take a look at machinery
associated with cutting metal plate and shapes. You
have already studied some of the equipment associated
Figure 13-20.--Examples of continuous identification
with cutting plate, such as the oxyacetylene torch,
marking.
mechanical hacksaw, and band saws that are found in
some of the smaller shops in the fleet. This section will
society or industrial association. Some of the
include such machinery as the shear, universal
designations used are as follows:
ironworker, Pullmax, and plasma arc machine.
CR--Cold rolled
Drop Shear
HR--Hot rolled
The drop shear enables the HT to produce quality
HT--Heat treated
work in minimum time. The drop shear is used to trim
AQ--Aircraft quality
metal and make straight cuts with square sides. Metal,
such as mild steel, black iron, copper, aluminum, and
1/4H--Quarter hard
stainless steel, can be cut on the drop shear.
HTQ--High tensile quality
You have already been introduced to the squaring
shear in chapter 12 of this text. The drop shear is very
Specification data, such as the revision letter of
similar to the squaring shear but the drop shear is
the specification number, type, grade, class of
designed to cut thick plates. Most drop shears on ships
material or manufacturer's specification data,
and at shore facilities are designed to cut plate from l/8
such as heat number.
to l/2 inch thick. Metal thinner than l/8 inch should be
Small metal shapes, such as small tubing, coils of
cut on a squaring shear in the sheet metal shop since the
wire, and bar stock, cannot be marked readily by this
drop shear would just bend the sheet metal around the
method. On these items, the material may be tagged.
knives. Drop shears at some shipyards are designed to
Whenever a piece of material is removed from the
cut plate 1 inch and thicker.
original piece, you should mark the piece if the marking
SHEAR SAFETY.--As with any job or
label is incomplete or destroyed. This will prevent the
equipment, safety should be your primary concern. The
piece from being mistaken for another type of material
drop shear is a very dangerous piece of equipment to
or from being used where it shouldn't be used.
operate due to the force required to cut thick metal. As
you can imagine, it requires a lot of shearing force to
SHIPFITTER SHOP EQUIPMENT
cut thick plate. To compound this danger, the shearing
force is accomplished in one stroke of the machine.
Shipfitter shops, whether ashore are afloat, are
Once you have tripped the release lever, the shearing
equipped with some of the largest, most powerful, and
action is nonstoppable until the machine has made one
13-19
