17730-299
25
Preventive Maintenance
ULTIMAAX
®
for Fire and Rescue Vehicles
SHOCK ABSORBERS
FIGURE 6-27
NOTE
It is not necessary to replace shock absorbers in pairs
if one shock absorber requires replacement .
Hendrickson offers a long service life, premium shock
absorber for use on ULTIMAAX suspensions . If shock
absorber replacement is necessary, Hendrickson rec-
ommends that original Hendrickson shock absorbers
be replaced with identical Hendrickson Genuine
parts for servicing . Failure to do so will affect the
suspension performance, durability, and will void the
warranty .
Inspection of the shock absorber can be performed
by doing a heat test, and a visual inspection . For
instructions on shock absorber replacement see the
Component Replacement Section of this publication .
HEAT TEST
1 . Drive the vehicle at moderate speeds on rough
road for minimum of fifteen minutes .
DO NOT GRAB THE SHOCK AS IT COULD POSSIBLY CAUSE PERSONAL INJURY .
2 . Use an infrared thermometer to check the temperature of the shock absorber . This can also
be performed by carefully touching the shock body below the dust cover . Touch the frame to
get an ambient reference, see Figure 6-27 . A warm shock absorber is acceptable, a cold shock
absorber should be replaced .
3 . To inspect for an internal failure, remove and shake the suspected shock . Listen for the sound
of metal parts rattling inside . Rattling of metal parts can indicate that the shock has an inter-
nal failure .
VISUAL INSPECTION
Look for any of the potential problems shown in Figure 6-28 when doing a visual inspection .
Inspect the shock absorbers fully extended . Replace as necessary .
FIGURE 6-28
SHOCK ABSORBER VISUAL INSPECTION - UNACCEPTABLE CONDITIONS