Setscrew, plug, and flare nut wrenches.
(g) Setscrew and hollow-head capscrew wrenches. Most setscrews and
hollow-head capscrews have a hexagon (six-sided) socket. The commonly known key
(Allen) wrench (fig 9) is L-shaped, is made of tool steel, and has a hexagonal or
square section to fit these screws. Splined setscrew wrenches (fig 9) are made of
round stock with ends to fit little flutes or splines in headless setscrews. A
hollow-head capscrew set is also supplied. This set has detachable sockets which
are used with the accompanying handles.
(h) Plug wrenches. A plug wrench is a straight bar having a hexagon or
square shape and is available in a range of sizes from 3/8 to 1 inch in width.
They are usually 2 inches long. Plug wrenches are also made to fit drain plugs of
transmissions, differentials, and all types of gearcases. The multiple plug wrench
is a combination type having several different size and shape ends. Most plug
wrenches are made for a specific size plug. There are single-end plug wrenches
that range in size from 3/16 to 11/16 inch with a hexagonal or square end. Double-
end plug wrenches with square ends are issued for 3/8-and 1/2-inch plugs and 3/8-
and 3/4-inch plugs. These wrenches are normally 8 to 12 inches long. Socket plug
wrenches (fig 9) have a 1/2-inch square drive to be used with socket wrench handles.
(i) Flare nut wrenches. A flare nut wrench (fig 9) is a notched thin
walled split box wrench especially designed to fit over nuts in very close places.
It is ideal for tightening brass tube flare nuts. It grips the nut on five sides;
thus, it does not slip and mar the nut. Flare nut wrenches are of 12-point design
and have either a single or double end. Openings range in size from 3/4 to 1-5/8