Hydraulic Brake Pads
Brake pad lining life will vary depending on vehicle
application, working environment, equipment
maintenance, and style of driving. The brake pad lining
wear rate has to be monitored for individual driving
habits — original equipment linings have mechanical
wear indicators to help with this. When you are down to
the last 10% of the brake lining, the brake lining wear
indicator will rub on the rotor, causing a scratching or
chirping sound. When you hear this sound, it is time to
service the brake pads. See Scheduled Maintenance on
page 6-5.
Aftermarket brake linings might not meet the same
stringent requirements as the original equipment linings.
Using aftermarket brake linings can affect braking
performance, pedal feel, noise, and lining wear.
Air Brake Systems
If your vehicle has air brakes, it is important to get rid of
moisture in the system. Moisture will damage the
system if it is not removed daily.
There are two ways to do this. One is automatic through
the air brake vehicle’s air dryer with integral automatic
moisture ejector that purges air from the system through
a self-contained reservoir. The other way to drain
moisture from the air brake system is to manually activate
drain valves at each reservoir. Drain the air reservoirs
occasionally to be sure the air dryer is working properly.
Drain the air brakes at full system pressure. To be sure
you are at full pressure, check the air pressure gage.
It should read at least 100 psi (692 kPa).
Air Dryer
If your vehicle has air brakes, it has an air dryer
mounted on the passenger side frame rail. This collects
and removes dirt, moisture, or other foreign matter
from the air prior to entering the brake system. The dryer
also acts as a moisture ejector. It automatically ejects
the moisture when the compressor cycles. The
purge tank has a manual drain valve that must be
drained every day. See “Air Brake Systems” for the
manual drain procedure.
The dryer has a filter that you need to change at
intervals. See Scheduled Maintenance on page 6-5 for
more about servicing this filter.
Electric Air Compressor
Your vehicle might have an electric air compressor. This
compressor is used to run options that require
pressurized air, such as an air horn or air seat.
The air compressor is used when vehicles do not have
an air brake system.
5-60