Trailer Talk

Tips for Inspecting and Maintaining Air Suspensions

July 7, 2010

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Air suspensions are in wide use on trailers and getting more popular. To some fleets, air-ride equipment is new, and maintenance people might not be aware of proper inspection and repair procedures.

Sage mechanics will always educate themselves by seeking training offered by component manufacturers, whether in person, online or if nothing else, consulting manuals. Each suspension manufacturer has maintenance manuals that walk a technician through the replacement of components.

Experts at ArvinMeritor, one of the major makers of air-ride suspensions, checked their own manuals to compile these recommendations for technicians. The first steps are for inspections:

* Before each trip, visually inspect the suspension system and listen for any air leaks.

* Look at the height control valve and axle(s) at regular intervals during normal operation and each time the trailer is serviced. Replace damaged fasteners and properly torque them per specifications to comply with warranty requirements.

Perform the following inspections after the first 1,000 miles of operation, each time the trailer is serviced, and annually:

* Check torque values on all nuts and bolts, and properly tighten loose fasteners. Check the manual to find the correct torque values for each fastener. Replace damaged or missing fasteners with the proper parts.

* Check for loose pivot bolts. If they are loose, align the axles before tightening the bolts.

For Maintenance:

1. Look for broken and missing fasteners, and repair or replace as needed.

2. Inspect welds for cracks at the trailing arm, axle subassembly and hanger assemblies.

3. Check the flex-member of the air springs for any cuts and abrasions. Replace the air spring immediately if it is cut or damaged.

4. Check for obstructions and interference at the air springs that may cause scuffing and abrasions. Relocate and secure items such as air hoses that can contact any part of the air spring.

5. Check for leaks in the air lines, at the air spring upper bead plate, piston and mounting studs. Replace leaking air lines, fittings or air springs.

6. Check the shock absorber bushings for looseness and wear. Inspect the shock absorbers for oil leaks and dents. Replace worn or damaged shock absorbers.

7. Inspect the structure of these air suspension components:

a. Hanger assemblies

b. Trailing arm and axle subassembly

c. Shock mountings

d. Axle-to-trailing arm connection

e. Brake interference, cam or chamber

f. Hanger assembly bracing at interface points

g. Pivot connections

It is important when replacing parts, especially air springs and trailing arms, to use only components approved by the suspension manufacturer. Suspension components are specifically designed to operate together, and changing from an original component to one that hasn't been designed for the suspension could lead to decreased suspension performance and possible damage.

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Author Bio

Tom Berg

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Senior Contributing Editor

Journalist since 1965, truck writer and editor since 1978. CDL-qualified; conducts road tests on new heavy-, medium- and light-duty tractors and trucks. Specializes in vocational and hybrid vehicles.


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