DE2257173C3

DE2257173C3 - Automatic adjustment device for internal shoe brakes

Info

Publication number: DE2257173C3
Application number: DE19722257173
Authority: DE
Inventors: Felix 6370 Oberursel Kaiser
Original assignee: Alfred Teves GmbH
Current assignee: Continental Teves AG and Co oHG
Priority date: 1972-11-22
Filing date: 1972-11-22
Publication date: 1980-08-28
Also published as: FR2208485A5; GB1447388A; IT999414B; DE2257173A1; DE2257173B2

Description

Nachstellbolzen und einer Halteschraube,Adjustment bolt and a retaining screw,

Fig. 6 eine Seitenansicht des Radzylinders nach Fig. 5 im Schnitt.6 shows a side view of the wheel cylinder according to FIG. 5 in section.

In dem Radzylinder 1 sind zwei Bremskolben 2 gegenseitig zueinander angeordnet. In die Zylinderbohrungen 3 der Bremskolben 2 sind Büchsen 4 fest eingepreßt. Diese Büchsen 4 sind mit einem Sägezahngewinde 5 ausgebildet, welches in das gleichartige Gewinde der Nachstellbüchse 6 eingreift, die vier Längsschlitze 7 aufweist, wodurch vier Federaime entstehen. Diese Nachstellbüchse 6 sitzt gleitend auf dem Nachstellbolzen 8. der quer zur Bolzenachse eine Bohrung hat, in der ein Spannstift 9 befestigt ist. Der einen zylinderfesten Anschlag bildende Spannstift 9 ragt auf beiden Seiten in zwei gegenüberliegende Längsschlitze 7 der Nachstellbüchse 6 hinein. Die geschlossenen Enden dieser Längsschlitze 7 bilden gleichzeitig den Anschlag 10 für den Spannstift 9. Die Nachstellbolzen 8 liegen in der Bremslösestellung mit ihren konisch ausgebildeten Enden 11 an den entsprechend ausgebildeten Innenflächen 12 der Federarme auf. Die entgegengesetzten Enden 13 der Nachstellbolzen 8 sind abgeflacht und liegen mit den abgeflachten Teilen aufeinander. Die Teile 4 bis 13 bilden ein linear wirkendes in Löserichtung der Bremse sperrendes Richtgesperre. Eine an ihrem Ende zapfenförmig ausgebildete Halteschraube 15 ist durch eine beide Nachstellbolzen durchdringende Bohrung 16 geführt und verbindet die Nachstellbolzen 8 miteinander. Die Halteschraube 15 ist in eine Bohrung 17 des Zylindergehäuses eingeschraubt und mit einer Längsbohrung 18 versehen, in die das Entlüftungsventil 19 eingeschraubt ist. Das Einschrauben der Halteschraube 15 erfolgt über einen Innensechskant 14, der an ihrem oberen Ende eingearbeitet ist. Um vor dem Ausbau der Bremstrommel die Bremsbacken zurückzustellen, wird die Halteschraube 15 entfernt. Hierdurch wird die Verbindung zwischen den beiden Nachstellbolzen 8 gelöst, so daß diese wegen des zwischen ihnen vorhandenen Spiels sich aufeinanderzu bewegen könner, um dadurch ein Entfernen der Bremsbacken von der Bremstrommel um das erforderliche Maß zu ermöglichen. In the wheel cylinder 1, two brake pistons 2 are mutually arranged. In the cylinder bores 3 of the brake piston 2 sleeves 4 are firmly pressed. These sleeves 4 have a buttress thread 5 formed, which engages in the similar thread of the adjustment sleeve 6, the four Has longitudinal slots 7, whereby four Federaime arise. This adjustment sleeve 6 is slidably seated the adjusting bolt 8, which has a hole transversely to the bolt axis in which a dowel pin 9 is attached. Of the A dowel pin 9, which forms a fixed cylinder stop, protrudes into two opposite sides on both sides Longitudinal slots 7 of the adjustment sleeve 6 into it. The closed ends of these longitudinal slots 7 form at the same time the stop 10 for the dowel pin 9. The Adjusting bolts 8 are in the brake release position with their conical ends 11 on the corresponding formed inner surfaces 12 of the spring arms. The opposite ends 13 of the adjustment bolts 8 are flattened and lie on top of each other with the flattened parts. Parts 4 to 13 form a directional lock acting linearly in the brake release direction. One at its end is cone-shaped formed retaining screw 15 is guided through a bore 16 penetrating both adjustment bolts and connects the adjusting bolts 8 to one another. The retaining screw 15 is in a bore 17 of the cylinder housing screwed in and provided with a longitudinal bore 18 into which the vent valve 19 is screwed is. The screwing in of the retaining screw 15 takes place via a hexagon socket 14, which is attached to her upper end is incorporated. To reset the brake shoes before removing the brake drum, the retaining screw 15 is removed. This creates the connection between the two adjustment bolts 8 solved so that they can move towards each other because of the game between them, in order to enable the brake shoes to be removed from the brake drum by the required amount.

In den Fig. 3 und 4 sind die Nachstellbolzen so ausgebildet, daß der eine Nachstellbolzen 21 in eine Längsbohrung des anderen Nachstellbolzens 22 hineinragt. Die Halteschraube 23 hat eine Längsbohrung 24 zum Durchtritt des Druckmittels.In Figs. 3 and 4, the adjustment bolts are designed so that one adjusting bolt 21 protrudes into a longitudinal bore of the other adjusting bolt 22. The retaining screw 23 has a longitudinal bore 24 for the pressure medium to pass through.

In den Fig. 5 und 6 ist die Halteschraube 25 mit einem Sechskantkopf 25 ausgebildet.In FIGS. 5 and 6, the retaining screw 25 is designed with a hexagonal head 25.

Hierzu 3 Blatt ZeichnungenFor this purpose 3 sheets of drawings

Claims

Patent claims:

1.Automatic adjustment device for inner shoe brakes, with one arranged between the adjacent ends of the brake shoes, pressure medium-actuated wheel cylinder in which a brake piston is guided, which is connected to a Adjustment bolt sliding adjustment sleeve via a linear acting, \ on externally non-resettable Richtgesperre is connected that one movement of the brake piston in the actuation direction relative to the adjustment sleeve and in the release direction locks, with one in the socket provided longitudinal slot, the ends of which form movable stops that are fixed to a cylinder Stop cooperating and the free movement of the adjusting sleeve in the axial direction Limit the nominal clearance, and with an externally accessible, screwed into the wheel cylinder and the retaining screw protruding radially into the cylinder bore with its free end, after removing them, the brake piston with the adjustment sleeve shows play in the release direction, which allows the expansion of the brake drum in its axial direction, marked with the combination of the following features:

a) in the wheel cylinder (1) are two counter-rotating brake pistons (2) in a known manner provided, between which two independently acting directional locks (4 to 13) are arranged;

b) the inner, mutually adjacent ends of the two adjusting bolts (8, 21, 22) overlap in the axial direction,

c) the free end of the retaining screw (15; 23; 25, 26) engages in one of the two adjusting bolts without play (8, 21, 22) in the area of the overlap penetrating bore (16);

d) the game (20) required to remove the brake drum is between the inner end of one adjustment bolt (8, 21, 22) and a further stop of the other Adjustment bolts (8, 22, 21) are provided.

2. Automatic adjusting device according to claim 1, characterized in that the overlapping ends of the two adjusting bolts (8) are flattened and with the flattened parts lie on one another.

3. Automatic adjusting device according to claim 1, characterized in that the inner End of one adjusting bolt (21) into a blind hole in the other adjusting bolt (22) protrudes.

4. Automatic adjustment device according to one of claims 1 to 3, characterized in that that the retaining screw (23) has in a known manner a longitudinal bore (24) through which the pressure medium is supplied.

5. Automatic adjustment device according to one of claims 1 to 3, characterized in that that the retaining screw (15) has a longitudinal bore (18) into which the vent valve is screwed is.

6. Automatic adjustment device according to one of claims 1 to 3, characterized in that that the retaining screw (15) is designed as a vent valve.

The invention relates to an automatic adjustment device for inner-shoe brakes according to the preamble of claim 1.

With such adjusting devices that cannot be reset without removing the brake drum it is necessary to create an additional reset option for the brake shoes in order to remove the brake drum even if the brake shoes are in the friction surface of the brake drum

ι »have incorporated and the edge of the brake drum has rust blooms, so that the Adjustment device set brake clearance is not sufficient to the arched brake drum edge to pull over the brake shoes.

ι> An adjusting device mentioned at the beginning is from FR-PS 730 2 H) known. The wheel cylinder in which this adjusting device is installed has a single brake piston. An arrangement of the known adjusting device in a wheel cylinder

2 »with two acting in opposite directions Brake piston would double the already existing large overall length, which is the case with the small one Installation space that is available for brakes on motor vehicles would be a disadvantage.

2-, Furthermore, from DE-OS 1 655 384 a wheel cylinder known with two brake pistons movable in opposite directions, those of the adjusting device described above except for the arrangement of an externally accessible screwed into the wheel cylinder and

ίο with its free end radially into the cylinder bore corresponding retaining screw protruding, after removing the brake piston with adjustment sleeve Has play in the release direction, which allows the expansion of the brake drum in the axial direction. That

η However, the absence of these features leads to that the brake drum can no longer be removed if the brake shoes are in the friction surface have incorporated the brake drum.

It is therefore the object of the invention to provide an automatic

4I term adjustment device for inner shoe brakes to create according to the generic term with two brake pistons, with a simple structure and small size it is easy to reset the brake shoes before removing the brake drum

• Γ) possible.

This object is achieved according to the invention by the combination of the features of the identifier of the Claim 1 solved.

Advantageous further developments of the invention are

-, (i characterized in the subclaims.

Embodiments of the invention are shown in the drawing and are described in more detail below.
It shows

1 shows a longitudinal section through the wheel cylinder an inner shoe brake with two overlapped adjustment bolts and one as a vent valve connection trained retaining screw,

Fig. 2 is a side view of the wheel cylinder according to

Wi Fig. T in section,

3 shows a longitudinal section through the wheel cylinder of an inner shoe brake with two mutually displaceable Adjusting bolt and a retaining screw designed as a pressure medium connection,

(, ι-, Fig. 4 is a side view of the wheel cylinder according to Fig. 3 in section,

Fig. 5 shows a longitudinal section through the wheel cylinder of an inner shoe brake with two overlapped