Self-Locking Fasteners; Recommendations For Reuse - PREVOST H3-41 Maintenance Manual

4.3 SELF-LOCKING FASTENERS

A self-locking fastener is designed with an
interference fit between the nut and bolt threads.
This is most often accomplished by distortion of
the top thread of an all-metal nut or bolt or by
using a nylon patch on the threads. A nylon
insert or the use of adhesives may also be used
as a method of interference between nut and
bolt threads (Figure 13).
FIGURE 13: SELF-LOCKING FASTENERS

4.4 RECOMMENDATIONS FOR REUSE

Clean, rust-free self-locking fasteners may be
reused as follows:
SELF-LOCKING TORQUE CHART BEFORE FASTERNER SEATS
METRIC
NUTS AND
ALL-METAL BOLTS
ADHESIVE OR NYLON
COATED BOLTS
US STANDARD
NUTS AND
ALL-METAL BOLTS
ADHESIVE OR NYLON
COATED BOLTS
00004
6 & 6.3 8
Nm 0.4 0.8
lb-in 4.0 7.0
Nm 0.4 0.6
lb-in 4.0 5.0
¼ 5/16
Nm 0.4 0.6
lb-in 4.0 5.0
Nm 0.4 0.6
lb-in 4.0 5.0
PA1621 Maintenance Manual All Series | Section 00 revised Sept 2019
SECTION 00 : GENERAL INFORMATION
a) Clean dirt and other foreign matter from
the fastener;
b) Inspect the fastener to ensure there is no
crack, elongation, or other sign of fatigue
or over tightening. If there is any doubt,
replace with a new self-locking fastener of
equal or greater strength;
c) Assemble parts and hand start fastener;
d) Observe that, before the fastener seats, it
develops torque per the chart in the
following table. If there is any doubt,
replace with a new self-locking fastener of
equal or greater strength;
e) Tighten the fastener to the torque specified
in the applicable section of this manual;
Fasteners which are rusty or damaged should be
replaced with new ones of equal or greater
strength
.
10 12
1.4 2.2
12 18
1.2 1.6
10 14
3/8 7/16 ½
1.4 1.8 2.4
12 15 20
1.0 1.4 1.8
9.0 12 15
14 16 20
3.0 4.2 7.0
25 35 57
2.4 3.4 5.6
20 28 46
9/16 5/8 ¾
3.2 4.2 6.2
27 35 51
2.6 3.4 5.2
22 28 43
13