Chevrolet TrailBlazer, Service Manual

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Cleanliness and Care, Shop Practice
It should be understood that proper cleaning and protection of machined surfaces
and friction areas is part of the repair procedure. This is considered standard shop
practice even if not specifically stated.
When any internal engine parts are serviced, care and cleanliness is important.
When components are removed for service, they should be marked, organized or
retained in a specific order for reassembly.
At the time of installation, components should be installed in the same location and
with the same mating surface as when removed.
An automobile engine is a combination of many machined, honed, polished and
lapped surfaces with tolerances that are measured in millimeters or thousandths of
an inch. These surfaces should be covered or protected to avoid component
damage.
A liberal coating of clean engine oil should be applied to friction areas during
assembly.
Proper lubrication will protect and lubricate friction surfaces during initial operation.
Basic Operating Principles
Hydraulic systems are used to actuate the brakes of all modern automobiles. The system
transports the power required to force the frictional surfaces of the braking system together
from the pedal to the individual brake units at each wheel. A hydraulic system is used for
two reasons.
First, fluid under pressure can be carried to all parts of an automobile by small pipes and
flexible hoses without taking up a significant amount of room or posing routing problems.
Second, a great mechanical advantage can be given to the brake pedal end of the system,
and the foot pressure required to actuate the brakes can be reduced by making the
surface area of the master cylinder pistons smaller than that of any of the pistons in the
wheel cylinders or calipers.
The master cylinder consists of a fluid reservoir along with a double cylinder and piston
assembly. Double type master cylinders are designed to separate the front and rear
braking systems hydraulically in case of a leak. The master cylinder converts mechanical
motion from the pedal into hydraulic pressure within the lines. This pressure is translated
back into mechanical motion at the wheels by either the wheel cylinder (drum brakes) or
the caliper (disc brakes).
Steel lines carry the brake fluid to a point on the vehicle's frame near each of the vehicle's
wheels. The fluid is then carried to the calipers and wheel cylinders by flexible tubes in
order to allow for suspension and steering movements.
In drum brake systems, each wheel cylinder contains two pistons, one at either end, which
pushes outward in opposite directions and force the brake shoe into contact with the drum.
In disc brake systems, the cylinders are part of the calipers. At least one cylinder in each
caliper is used to force the brake pads against the disc.