flattens, or straightens, a spring section. Many
types of spring nuts use curved metal springs,
bellows, and coil springs. All spin on and off
without locking until the pressure against the
working surface straightens the spring.
You should always consult equipment
manuals for the proper torque value. Be sure
threads are always clean and lightly lubricated
with the proper lubrication. Discard any with
damaged threads.
Figure 6-57.--Helical spring lockwasher.
Spring Beam Nuts
down. When torqued, it acts as a flat washer
Spring beam nuts (fig. 6-56) are formed with
contributing normal friction for locking the screw
a light taper in the threads toward the upper
or bolt and the working surface; it also maintains
portion of the nut. Slots are cut in the outer
the tension on the bolt. Because of the helical
portion, forming segments that can be forced out-
spring lockwasher's small diameter, it is usually
ward when the nut is installed. Elastic reaction
not used on soft materials or with oversized or
causes the segments to push inward, gripping the
elongated holes.
bolt. Like the nylon insert nut, this nut does not
deform the bolt threads and can be used on
Curved or Conical Spring Lockwashers
frequently removed items. If you can thread the
nut past the deflection segments without a wrench,
Curved or conical spring lockwashers have
discard the nut and replace it with a new one.
almost the same properties as the helical spring
lockwasher. They provide a constant tension on
LOCKWASHERS
the bolt or screw when loosened. The tension
Many installations on board naval ships still
produced is usually less than that produced by the
use lockwashers to prevent threaded fasteners
helical spring lockwasher. Like any locking device
from loosening. If loosening has not been a
relying on tension, spring lockwashers may loosen
problem, you may replace worn lockwashers with
on shock loading. When the bolt stretches more
an identical type; however, if loosening has been
than the spring distortion from the shock loading,
a problem, you should use self-locking fasteners
the washer serves no further purpose. Recheck the
instead of lockwashers.
washer, where possible, when shock is sufficient
The most common lockwasher used is the
to suspect loosening. Some spring lockwashers
helical spring washer. Other types are the conical
have teeth on the outer edge. These teeth do not
and toothed tab.
aid in locking, but they prevent side slippage and
turning.
Helical Spring Lockwashers
Toothed Lockwashers
The helical spring lockwasher (split ring)
(fig. 6-57) is flattened when the bolt is torqued
Toothed lockwashers (fig. 6-58) have teeth that
are twisted or bent to prevent loosening. Cutting
Figure 6-58.--Toothed lockwashers.
Figure 6-56.--Spring beam nuts.
6-39
