truck shock absorber inspection procedures

8/19/2019 Truck Shock Absorber Inspection Procedures

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Information contained in this literature was accurate at the time of publication, product changes may have been made after the publication date that are not reflected here

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97117-208

THE BOLER COMPANYCOPYRIGHT ©2009

HENDRICKSON ASIA PACIFIC PTY LTDALL RIGHTS RESERVED

ABN 21 004 992 76932-44 Letcon Dve/P.O. Box 1063,Dandenong, South Vic 3175 Australia

Phone 61.3.8792 3600 Fax 61.3.8792.3699

www.hendrickson.com.au

No: 97117-208Subject: SHOCK ABSORBER INSPECTION PROCEDURES Date: December - 2009 Revision: A

TRUCK SUSPENSION

1. The role of the shock absorber has changed dramatically. Not so many years ago most suspensions hadheavy multi-leaf springs with limited travel and a great deal of inherent friction. These suspensions quickly selfdampened and therefore limited the amount of work that the shock absorber needed to perform.

2. Low-friction suspensions, such as air, have dramatically changed the shock absorbers role and theircharacteristics. Shocks now perform a critical role in dampening suspension oscilliation. Properly functioningshock absorbers can help reduce the wear of more expensive suspension components, such as air springs,while assisting in the reduction of tyre wear. Worn shock absorbers simply cannot assist in providing control

over today’s sophisticated suspensions systems.

3. Like most other suspension components, a program of regular scheduled preventative maintenance forshock absorbers, will avoid unscheduled downtime and reduce overall maintenance costs.

INTRODUCTION

GUIDE TO INSPECTING SHOCK ABSORBERS


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TRUCK SUSPENSION – SHOCK ABSORBER INSPECTION PROCEDURES


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97117-208




Phone 61.3.8792 3600 Fax 61.3.8792.3699


4. Shock absorbers function at temperatures ranging fromambient to 175 deg C (350 deg F). A shock’s role is to dampen

the oscillation of the suspension. It does this by transformingthe energy produced by the air springs to heat and dissipatingit. As a result the shock should be slightly warm to hot to touchafter normal use.

5. If ride deterioration is experienced and there issuspicion that a shock has failed internally, which is visuallyundetectable, perform the following SHOCK HEAT TEST:

a. Operate the vehicle at moderate speeds for at leastfifteen minutes

b. Within a few minutes of driving the vehicle, toucheach shock absorber carefully on its body belowthe dust cover or tube (Figure 1.) after first touchinga nearby part of the frame to establish a referenceambient temperature of the metal.

c. All shock absorbers should be warmer than thevehicle frame. Suspect a failure in any shockabsorber that is noticeably cooler than its mate onthe other end of the axle. Different temperature onany axle warrants removal and examination of thecooler shock absorber.

d. To inspect for an internal failure, remove and shakethe suspected shock absorber. Listen for thesound of metal parts rattling inside. Rattling ofmetal parts can indicate that the shock has aninternal failure and requires replacement.

TAKE THE HEAT TEST

TO AVOID SKIN DAMAGE FROM EXCESSIVE HEAT,

FEEL FOR SHOCK ABSORBER TEMPERATURE, WITHTHE BACK OF YOUR HAND

Figure 1


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Phone 61.3.8792 3600 Fax 61.3.8792.3699


5. There are many tell tale signs that indicate it may be time to replace shock absorbers:

INSPECT FOR :

UNEVEN TYRE WEAR

Check balance first

RIDE DETERIORATION

BROKEN OR TORN AIR SPRINGS

Shocks will affect air springs only if they are broken or missing.

Any questions in relation to this Technical Bulletin please forward to the Hendrickson Product SupportGroup: Telephone (03) 8792 3600 or email to: [email protected]

WHEN SHOULD SHOCK ABSORBERS BE REPLACED

SHOCK VISUAL CHECKS

truck shock absorber inspection procedures

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