Special Tools; Hydraulic Brake System; Operation Overview - Polaris A12MH46AX Service Manual

SPECIAL TOOLS

Special Tools
PN 2870975
SPX Corporation -
polaris.spx.com

HYDRAULIC BRAKE SYSTEM

Operation Overview

Must be clear to
allow proper
diaphragm
movement
F
A B
Move Brake Pad
The Polaris disc brake system consists of the following
components or assemblies: brake lever; master cylinder;
hydraulic hose; brake calipers (slave cylinder); brake
pads; and brake discs, which are secured to the drive line.
™
Mity Vac
1-800-328-6657 or http://
Compensating port
compensates for
E
temperature changes by
allowing fluid back to
master cylinder
C
D
9923412 - 2012 Sportsman 400/500 and EFI Tractor Service Manual
© Copyright 2011 Polaris Sales Inc.
When the hand activated brake lever (A) is applied it
contacts piston (B) within the master cylinder. As the
master cylinder piston moves inward it closes a small
opening (compensating port C) within the cylinder and
starts to build pressure within the brake system. As the
pressure within the system is increased, the piston (D)
located in the brake caliper moves outward and applies
pressure to the brake pad. This pad contacts the brake
disc and moves the caliper in its floating bracket, pulling
the stationary side pad into the brake disc. The resulting
friction reduces brake disc and vehicle speed. As the lever
pressure is increased, the braking affect is also increased.
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 (C) which is opened and closed by the master cylinder
piston assembly. The port is open when the lever is
released and the master cylinder piston is outward. As the
temperature within the hydraulic system changes, this port
compensates for fluid expansion (heated fluid) or
contraction (cooled fluid). During system service, be sure
this port is open. Due to the high temperatures created
within the system during heavy braking, it is very important
that the master cylinder reservoir has adequate space to
allow for fluid expansion. Never overfill the reservoir!
Fill to 1/4, - 5/16, (.64 - .80 cm) from top of the cylinder.
This system also incorporates a diaphragm (E) as part of
the cover gasket; and a vent port (F) located between the
gasket and the cover. The combination diaphragm and
vent allow for the air above the fluid to equalize pressure
as the fluid expands or contracts. Make sure the vent is
open and allowed to function. If the reservoir is over filled
or the diaphragm vent is plugged the expanding fluid may
build pressure in the brake system leading to brake fail
BRAKES
9
9.3