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Care and maintenance of springs
The leaf springs are working, flexible components and the main supporting members of a trailer suspension.
They cushion the trailer and its load from various road shocks and provide necessary stability. A reasonable
amount of care and maintenance is required to provide satisfactory service life. The springs must be tightly
clamped to the spring seat and the axle to prevent any movement between V-bolts, which results in
misalignment of axles. It is important that spring V-bolts be checked for proper tightness regularly during the
first few months of service or until such time as the spring leaves wear-in with usage. Thereafter, they should be
checked periodically as a matter of normal maintenance.
To obtain maximum service from the springs on your trailer, the following steps should be followed.
1. The V-bolts are adjusted to the suspension manufacturers' specifications before delivery of your semi
trailer. They should be retorqued at the end of 30 days of operation, but no later than 45 days. We
suggest that you return the unit to your PRATT for this adjustment.
2. Retorque V-bolts at regular maintenance intervals. A loose V-bolt permits play that results in breakage.
Checking the V-bolts frequently is a wise precaution since all V-bolts tend to stretch. All torquing should
be with dry threads.
3. Broken spring leaves between the U-Bolts indicate loose U-Bolts. Replace the spring at the earliest
opportunity.
4. Never replace only one leaf of a multiple spring. Replace the complete spring. Replacing a single spring
leaf may often be false economy. If one leaf is broken, the rest of the leaves have fatigued and are
probably ready to break also.
5. Always use hardened steel washers with-bolts and nuts. This provides uniform torque on the U-bolts.
6. Always replace U-bolts as a pair for best performance.
7. Cracked or broken springs outside the U-bolt are an indication of:
a. Repeated overload, or
b. Spring assembly has completes its normal life cycle. In either case, the entire spring assembly
should be replaced.
Remember, failure to retorque the U-bolts can result in improper axle alignment, spring breakage, abnormal
wear, and/or unsafe operating conditions. Make sure your suspension is always safe and road ready.
Air ride suspension maintenance
Checking trailer ride height
PREPARATION
1. Place the trailer on flat, level ground that is free of stones and debris.
2. Check air pressure in tires. If necessary, inflate tire(s) to proper pressure (figure 2).
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