Bar Pin End Bushing; Bar Pin Shim; Bolster Springs - ProGear Hendrickson HN FR Series Service Manual

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17730-285
Pro Gear and Transmission • 906 W. Gore St. Orlando, FL 32805 • 1 (877) 776-4600 / (407) 872-1901 • parts@eprogear.com

BAR PIN END BUSHING

An indication that the bar pin end bushing requires
replacement is when one or more of the following
conditions apply:
Visual inspection of contact area (the flat face
area where bar pin contacts the axle bracket) on
the bar pin reveals signs of excessive wear. If the
thickness of the bar pin in the contact area mea-
sures less than 1.874" (47.59 mm), bar pin end
bushing requires replacement, see Figure 6-5.
Visual inspection of the bolt holes in the bar
pin reveals signs of elongation or wear, see
Figure 6-5.

BAR PIN SHIM

An indication that the bar pin shims
require replacement is when one or
more of the following conditions apply:
Visual inspection of contact area
on the shim reveals signs of exces-
sive wear.
The thickness of any single leg on
the shim, is less than the measure-
ment shown in Figure 6-6, replacement of bar pin shim is required.

BOLSTER SPRINGS

Inspect all four bolster springs on a periodic basis. Actual bolster spring service condition and
performance may vary depending upon suspension and vehicle configuration, operation,
service and other factors. The following inspection guidelines are intended to assist vehicle
operators and maintenance personnel in examining the bolster springs and determining when
replacements may be needed. In the event one bolster spring on one equalizing beam assem-
bly shows signs of damage or excessive wear, Hendrickson recommends that both bolster
springs installed on that equalizing beam assembly be replaced. When the bolster springs are
replaced on one side only, the vehicle may lean slightly. The new bolster springs will tend to
settle to some degree, and return the vehicle to its original condition. The following procedure is
recommended for proper inspection.
1. Chock the front wheels to prevent movement of the vehicle during inspection of the
suspension.
2. Raise rear of vehicle approximately 4.0" - 5.0", (102 mm - 127 mm) just prior to lifting
wheels off ground, and support with stands.
3. Inspect all bolster springs using the following criteria. If cuts, splits, or bonding separation
are detected in the rubber, measure the depth of the damaged area using a six-inch ma-
chinist scale to determine if replacement is required.
Bent, burred or overhanging edges of the bolster spring metal plates may occur due
to mishandling in service. If the rubber is not trapped, and there are no sharp metal
edges in contact with the free surface of the rubber, this condition is acceptable.
Creases formed by folding of the rubber surface under load are acceptable. These creases
appear as stripes on the surface, polished by wear or covered with tacky rubber.
FIGURE 6-5
If bar pin measurement is
1.874" (47.59
replacement is required.
FIGURE 6-6
15
HN
®
FR Series
Rubber
Bar Pin Mount
Bolt Hole
Contact Area
1.874"
(47.59 mm)
less than
mm), component
Thickness
Minimum
of
Thickness
Shim Leg
Required
"
1
0.123" (3.1 mm)
8
"
3
0.186" (4.7 mm)
1 6
¼"
0.248" (6.3 mm)
"
3
0.371" (9.4 mm)
8
Preventive Maintenance

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