Page 19 - Catalog spare parts BPW brake disc
P. 19
AUTO PARTS
Page 19 - Catalog spare parts BPW brake disc
Auto Parts / Page 18 BPW-EL-TSB 31231601e
3 Brake parts BPW ECO Disc
TSB 3709 / 4309 / 4312
General
BPW ECO Disc Trailer disc brakes TSB 3709 / 4309 / 4312
OPERATING PRINCIPLE: SLIDING CALLIPER BRAKE
APPLYING THE BRAKE
During braking, the cylinder pushrod of the spring brake or diaphragm cylinder presses onto the brake
lever (1).
The offset position of the brake lever amplifi es the force created by the brake cylinder and allows it to be transferred
to the intermediate plate (2) with minimal loss via a needle bearing.
Mounted in the pressure plate (4), the intermediate plate counteracts the vertical movement of the lever and ensures
optimal transfer to the cross support.
The clamping force acts on the inner brake pad (7a) via the cross support (5) and the pressure plates (6).
Once the play between the inner brake pad and the brake disc (8) has been overcome, the reaction force is
transferred to the outer brake pad (7b) via the brake calliper.
The brake torque for the wheel is generated when the brake pads contact the brake disc.
The radial stabilizer force created by the responding brake pad at this time is transferred directly to the axle via
the brake calliper.
RELEASING THE BRAKE
When brake pressure rises, 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 constant clearance between
the brake pad and the brake disc.
Each time the brake is operated the axial movement of the lever block (2) and pressure plate (4) causes the adjuster
pin (11) to be rotated via a trapezoidal thread.
The adjuster pin is connected to the threaded tube (14) by the movement thread (11a) which in turn can rotate the
threaded tube (14) via the spring loaded indented ball coupling sleeve (12). When play increases the threaded tube
(14) is turned correspondingly via the indented ball coupling (12).
Axial play in the trapezoidal thread between the pressure plate (4) and the adjuster pin determines the free play
value of the disc brake.
When the free play is set correctly the spring loaded indented ball coupling sleeve (12) can disengage without
turning the threaded tube (14).
The overall play (total play on both sides of the disc brake) measures 0.7 - 1.3 mm.
RESET MECHANISM
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 pressure plates (6) can return to their initial position. Only minimal torque is required to move the pressure
plates (6) back to this position or preset the play.
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, apart from the sealing of the fl ange surface, are fi tted
with a so called „inner sealing“.
This means that the pushrod acting on the lever (1) must be hermetically sealed from the secondary chamber of
the brake cylinder as otherwise the internal mechanism is completely open to its surroundings.
