Automatic adjusting device for a brake
AssigneeLucas Industries public limited company
InventorsHeinrich-Bernhard Rath, Dietrich Holz
Life of this patent
Estimating the term…
Abstract
An adjusting device (24,34) of an automatically adjustable shoe drum brake has an at least prartly movable locking member (46) associated with it which cooperates with a heat sensitive spring element (50) and prevents pivoting of an adjusting lever (34) and consequently variation in length of a strut (24) in response to the magnitude of a predeterminable brake actuating force and/or a temperature. A loss distance caused by the movement of at least part of the locking member (46) is reduced by a change in rigidity and/or shape of the spring element (50) at rising temperature, in response to the temperature, and completely cancelled . . . reaching a predeterminable value of the temperature.
Claims12
In an automatic adjusting device for a brake, especially a motor vehicle brake with which a strut (24) is connected functionally in parallel with a brake actuator (16) and has an effective length which depends on the relative positions of two strut members (26,30) adjustable with respect to each other and one (26) of them having an adjustable portion connectable with an adjusting member by which the strut (24) is extendable upon actuation of the brake and which cooperates with at least one intermediate member (46) normally disposed between a brake shoe web (6) and a piston (18) for transmitting the brake actuating force to the web independently of the strut (24), as long as the brake actuating force does not exceed a predetermined amount, wherein said intermediate member comprises a locking member (46;246;350,360;446) having a side facing the piston (18) of the hydraulic actuator (16) and protrudes a predetermined salient distance (a) beyond the end of the web (6) facing the piston (18), when the brake is at rest, so that the brake actuating force is normally transmissible from the piston (18) to the web (6) by way of the locking member (46;246;350,446) until the salient distance (a) has been reduced by the movement of the locking member (46;246;350,446) relative to said web and the piston (18) abuts against the side of the web, a heat sensitive spring element (50;250;350) cooperating with the locking member (46;246;350,360,446), the characteristics of the spring element being variable with rising temperature of the brake such that movement of the locking member (46;246;350,446) relative to the web results whereby the salient distance (a) is reduced, and means for connecting said locking member (46;246;360,446) with said adjusting member (34,234,334,434) to prevent movement thereof and thus adjustment of said strut upon a predetermined reduction of said salient distance in response to a predetermined amount of at least one of the brake actuating force and a predetermined value of the temperature.
Dependencies are inferred from the claim text.