BENDIX A2LS Manuel - Page 2

Parcourez en ligne ou téléchargez le pdf Manuel pour {nom_de_la_catégorie} BENDIX A2LS. BENDIX A2LS 17 pages. Hydraulic drum brakes w/parking

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manual override access holes are covered by rubber

grommets.

WHEEL

CYLINDER

PISTONS

WHEEL

CYLINDER

PISTONS

FIGURE 2 - SERVICE BRAKE APPLICATION

OPERATION

On brake pedal application, hydraulic fluid pressure is

delivered to the wheel cylinder and expander unit. This

hydraulic pressure forces the wheel cylinder pistons

outwards, Figure 2, moving the brake shoes against the

drum. At the same time hydraulic pressure also forces the

input tappet piston and abutment tappet in the expander

unit outward, moving the opposite end of the brake shoes

toward the drum. The expander input tappet/piston pushes

against one shoe, and the roller tappet/piston pushes on

the expander abutment tappet and through this to the other

shoe.

(ARROW INDICATES DIRECTION OF DRUM ROTATION)

TORQUE

LOAD

FIGURE 3 - FORWARD DRUM ROTATION

INPUT/

TAPPET

PISTON

ROLLER/TAPPET

PISTON

ABUTMENT

TAPPET

TORQUE

LOAD

(ARROW INDICATES DIRECTION OF DRUM ROTATION)

TORQUE

LOAD

FIGURE 4 - REVERSE DRUM ROTATION

When the brake shoe lining contacts the drum the shoes

are forced around, sliding on the abutments, in the direction

Of drum rotation. In the forward direction, Figure 3, the torque

load from one shoe is taken by the wheel cylinder piston

bottoming in its bore in the wheel cylinder, and from the

opposite shoe by the expander abutment tappet resting

against the expander unit body. In the reverse direction,

Figure 4, the torque load from one shoe is taken by the

other wheel cylinder piston bottoming in its bore in the wheel

cylinder, and from the opposite shoe by the expander input

tappet/piston head resting against the expander body. In

this way, regardless of forward or reverse drum rotation,

the brake will always be a two leading shoe brake.

PARKING BRAKE APPLICATION

On application of the parking brake, the spring actuator

screwed into the back of the expander unit housing pushes

the wedge assembly forward. As the wedge assembly moves

FIGURE 5 - PARKING BRAKE APPLICATION

TORQUE

LOAD

WEDGE

ASSEMBLY