|
The maximum
span of lock wire between points shall be six inches.
Where multiple
groups are lock by either the double twist or the single strand
method, the maximum number in a series shall be determined by
the number of units that can be lock wired by a twenty-four inch
length of wire.
Wire shall
be pulled taut while being twisted. The number of twists per
inch as recorded in Table 1-1, represents general practice and
is given as guidance information only.
Caution must
be exercised during the twisting operation to keep the wire tight
without overstressing. Abrasions caused by commercially available
wire twisting pliers shall be acceptable but nicks, kinks, and
other damage to the wire are not.
Lock wire shall
not be installed in such a manner as to cause the wire to be
subjected to chafing, fatigue through vibration, or additional
tension other than the tension imposed on the wire to prevent
loosening. In the event that no wire hole is provided, wiring
should be to a convenient neighboring part in a manner so as
not to interfere with the function of the parts. Hose and electrical
coupling nuts shall be wired in the same manner as tube coupling
nuts.
Various examples
of lock wiring are shown in Figures 1-1 through 1-12. Figure
1-12 shows the single-stranded method, while the other figures
show the two-stranded or double twist method.
Detail Instructions For The Installation
Of Lock Wire
Check the units
to be lock wired to make sure that they have been correctly torqued.
Under-torquing or over-torquing to obtain proper alignment of
the holes is not advisable. If it is impossible to obtain a proper
alignment within the specified torque limits, back off the unit
and try it again or select another unit.
In adjacent
units, it is desirable that the holes be in approximately the
same relationship to each other as shown in Figures 1-1 through
1-4 (for right-handed threads), thus the lock wire will have
a tendency to pull the unit clockwise. This should be reversed
for left-handed threads.
Where lock
wire is used to secure a castellated nut on a threaded item,
selection of locking hole diameter for the item shall be based
on cotter pin requirements.
Table 1-1
Lockwire
and Lockwire Hold Data
Wire Diameter
Twists per Inch Recommended Hole Diameter
0.020 9-12
0.037-0.057
0.025 9-12 0.060-0.080
0.032 7-10 0.060-0.080

|