AUTO PARTS

Page 24 - Catalog spare parts BPW EL-TS2

Auto Parts / Page 24 BPW-EL-TS2/TSB 31231902e
3 BPW ECO Disc brake parts

3.5 Functional principle (TSB)

BPW ECO Disc disc brakes TSB 3709 / 4309 / 4312
FUNCTIONAL PRINCIPLE: SLIDING CALIPER BRAKE (TSB)

APPLYING THE BRAKE
During braking, the push rod of the spring brake or diaphragm cylinder presses onto the brake lever (1). The of set
position of the brake lever ampliﬁ es the force created by the brake cylinder and allows it to be transferred to the
pressure plate (4) with minimal loss via a needle bearing (3).
The clamping force acts on the inner brake lining (7a) via the transverse (5) and the tappets (6).
Once the clearance between the inner brake lining and the brake disc (8) has been overcome, the reaction force is
transferred to the outer brake lining (7b) via the brake caliper.
The braking moment for the wheel results from the contact pressure of the brake linings on the brake disc.
The radial stabilizer force created by the responding brake lining at this time is transferred directly to the axle via
the brake calliper.

RELEASING THE BRAKE
When brake pressure decreases, the pressure spring (9) moves the actuating unit back to its initial position.

ADJUSTMENT
The brake is ﬁ tted with an automatic non-wearing adjusting device (10) to maintain a constant clearance between
the brake linings and the brake disc.
Each brake application simultaneously activates the adjuster pin (11), which is coupled with the brake actuating
unit via a movement thread (11a). The axial clearance of the trapezoidal thread determines the clearance value of
the disc brake.
When the clearance increases due to brake lining and brake disc wear, the threaded tube (14) is turned by the
degree of wear through adjustment via a ball joint (12).
When the clearance is correctly set, the ball joint moves out without turning the threaded tube.
The overall clearance (total clearance on both sides of the brake disc) measures 0.7 − 1.3 mm.

RESET
The disc brake features a reset mechanism at the front for replacing the brake pads and brake disc.
The return spring gear wheel (13) is mechanically connected to the external gearing of the threaded tube (14) so
that the tappets (6) can return to their initial position. Only minimal torque is required to move the tappets (6) back
to their initial position or preset the clearance.

BRAKE CYLINDER
Air pressure builds up behind the diaphragm due to the action of compressed air on the brake cylinder.
Air pressure forces the thrust rod out of the cylinder via the diaphragm plate.
The brakes may only be ﬁ tted with brake cylinders which are ﬁ tted with a so-called “inner sealing”, apart from the
sealing of the ﬂ ange surface.
This means that the push rod acting on the lever (1) must be hermetically sealed from the secondary chamber of
the brake cylinder, as otherwise the clamping mechanism is completely open to its surroundings.

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