Ford F-650 2001 Owner's Manual page 212

General maintenance information
AIR BRAKE ADJUSTMENT
Failure to maintain proper air brake adjustment can result in
reduction or loss of braking ability.
Air brake inspection and adjustment should be performed by a qualified
service technician in accordance with the instructions in the Ford Truck
Service Manual.
Cam brakes - automatic slack adjusters
Inspect standard air brakes equipped with automatic slack adjusters for
proper brake adjustment every four months or 32 000 km (20 000 miles)
whichever occurs first.
However, more frequent inspection is required if your vehicle's brakes
are subjected to heavy use or adverse operating conditions such as:
• Frequent brake applications while fully loaded.
• Operation on hilly or mountainous terrain.
• Frequent operation on dirt, gravel or mud.
Some aftermarket brake linings also require more frequent inspections.
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