Hydraulic Brake System Operation - Polaris 2013 RANGER RZR S Service Manual

BRAKES

HYDRAULIC BRAKE SYSTEM OPERATION

The Polaris brake system consists of the following components or assemblies: brake pedal, master cylinder, hydraulic
brake lines, brake calipers, brake pads, and brake discs, which are secured to the drive line.
When the foot activated brake lever is applied it applies pressure on the piston within the master cylinder. As the master
cylinder piston moves inward it closes a small opening (compensating port) within the cylinder and starts to build pressure
within the brake system. As the pressure within the system is increased, the pistons located in the brake calipers move
outward and apply pressure to the moveable brake pads. These pads contact the brake discs and move the calipers in
their floating bracket, pulling the stationary side pads into the brake discs. The resulting friction reduces brake disc and
vehicle speed.
The friction applied to the brake pads will cause the pads to wear. As these pads wear, the piston within the caliper moves
further outward and becomes self adjusting. Fluid from the reservoir fills the additional area created when the caliper
piston moves outward.
Brake fluid level is critical to proper system operation. Too little fluid will allow air to enter the system and cause the brakes
to feel spongy. Too much fluid could cause brakes to drag due to fluid expansion.
Located within the master cylinder is the compensating port which is opened and closed by the master cylinder piston
assembly. As the temperature within the hydraulic system changes, this port compensates for fluid expansion or
contraction. Due to the high temperatures created within the system during heavy braking, it is very important that the
master cylinder reservoir have adequate space to allow for fluid expansion. Never overfill the reservoir! Do not fill the
reservoir beyond the MAX LEVEL line!
When servicing Polaris brake systems use only Polaris DOT 4 Brake Fluid (PN 2872189). WARNING: Once a bottle
is opened, use what is necessary and discard the rest in accordance with local laws. Do not store or use a partial bottle
of brake fluid. Brake fluid is hygroscopic, meaning it rapidly absorbs moisture. This causes the boiling temperature of
the brake fluid to drop, which can lead to early brake fade and the possibility of serious injury.
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9924125 - 2013 RANGER RZR / RZR S / RZR 4 Service Manual
© Copyright 2012 Polaris Sales Inc.