17730-299
21
Preventive Maintenance
ULTIMAAX
®
for Fire and Rescue Vehicles
FIGURE 6-18
■
Bonding separation of the rubber from any of the
bonded rate plate surfaces to a maximum depth
of approximately 2" (50 mm) is acceptable, see
Figure 6-18 . If the bonding separation depth is
2" (50 mm) or more, the shear springs require
replacement .
■
A certain amount of gradual breakup of the rubber sur-
face is acceptable . Use a feeler gauge to measure cuts
or splits in the rubber . If the measurement is over a
depth of 2" (50 mm), then the shear springs require replacement, see Figures 6-19 and 6-20 .
FIGURE 6-19
FIGURE 6-20
FIGURE 6-21
PROGRESSIVE LOAD SPRINGS (PLS)
NOTE
Hendrickson Lit. No. 48422-592
– ULTIMAAX Gauge
Card (Figure 6-21) can be used to measure in the
unloaded condition the height of the progressive load
spring (PLS), plus the length of cuts / splits and depth of
separation of the shear spring and the PLS .
Visually inspect the progressive load springs at
regular preventive maintenance intervals . The follow-
ing points are for guidance and intended to assist
personnel in determining when progressive load spring
component requires replacement, refer to the Component
Replacement Section of this publication .
NOTE
The Hendrickson ULTIMAAX suspension progressive load
springs must be replaced in pairs (left side pairs or right
side pairs or rear position pairs or front position pairs),
even if only one PLS shows unacceptable conditions .
Replacement of only one PLS can cause uneven wear,
and higher premature wear for the one replaced
■
Always inspect the progressive load spring with the
vehicle in the
UNLOADED
condition .
■
The height of a new PLS is 3
1
⁄
16
" (78 mm) . The PLS requires replacement if the height is below
2
5
⁄
16
" (59 mm), see Figure 6-22 .
