Modular disc brake and actuator lever therefor

Details Modular disc brake and actuator lever therefor Modular disc brake and actuator lever therefor

1998-11-30

2001-11-06

Graham, Matthew C. (Department: 3613)

Brakes

Wheel

Axially movable brake element or housing therefor

C188S072700

Reexamination Certificate

active

06311809

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to an actuator lever for a disc brake, a modular assembly incorporating an actuator lever, and a disc brake incorporating the actuator lever.
More particularly, the present invention relates to an actuator lever for a disc brake, a modular assembly incorporating an actuator lever, and a disc brake incorporating the actuator lever, of the type actuated by a fluid controlled brake applying means, particularly in the form of a pneumatically operated diaphragm cylinder.
DISCUSSION OF BACKGROUND
In known constructions of pneumatically operated disc brakes the basic construction includes an annular braking disc straddled by a clamp member or caliper containing an actuator mechanism which applies braking force to one side of the braking disc via a brake pad. The clamp member or caliper is mounted on a torque taking member so as to be slidable axially of the braking disc, whereby when the first mentioned brake pad is applied to one side of the braking disc, the clamp member/caliper slides axially of the brake disc to apply the other brake pad to the other side of the braking disc, thus completing the braking action. The brake pads are usually carried by the torque taking member which is fixedly secured to the vehicle.
In pneumatically operated disc brake constructions, of known type, the brake applying means incorporates a piston with a piston rod extending out of the chamber of the brake applying means, the piston engaging with a pivotal lever. In certain constructions the pivotal lever has at its end region remote from the piston rod, a curved supporting surface which sits in an appropriate bearing which is located between the curved surface and a fixed surface in the brake construction. Provided on another part of this other end region of the lever is a force transmitting member in the form of a cylindrical rod or roller which is located in a complimentary channel in the other end region of the lever with the force transmitting member being usually rotatable about its longitudinal axis in the channel with an appropriate bearing e.g., a proprietory PVDF, PTFE and lead composition, located between the cylindrical force transmitting member and the surface of the channel. One such construction is described in WO-A-92/07202.
The channel may be so located as to be axially offset from the pivotal axis of the said other end region of the lever i.e. the center of curvature of the cylindrical force transmitting member is spaced from the center of curvature of the curved surface at the other end region of the lever. This cylindrical force transmitting member engages an axially moveable tappet which can be adjustable in length i.e., it cooperates with an appropriate adjuster mechanism, the tappet acting either directly or via another member against the first mentioned friction pad. Thus, by pivoting the lever about the curved surface, the force transmitting member presses against the tappet applying the first mentioned brake pad against one side of the brake disc. The clamp member/calliper thus slides axially of the braking disc applying the other brake pad to the other side of the brake disc.
The above type of brake may have one adjustable length tappet or more usually, two adjustable length tappets, with an adjuster mechanism coupled to the pivotal lever whereby the tappet can be adjusted in length to cater for pad wear, the adjuster assembly acting on one tappet which is coupled to the other tappet for equivalent adjustment.
Whilst on assembly the attachment of the diaphragm/piston brake applying means to the brake construction with the piston rod engaging one end of the actuating lever is basically quite simple, it will be appreciated that the assembly and construction of the lever with the appropriate bearings and the force transmitting member together with the tappets and adjuster mechanism is quite complicated and an expensive manufacturing operation.
SUMMARY OF THE INVENTION
It is thus the aim of the present invention to simplify the construction and to provide an improved form of adjuster mechanism form of adjuster mechanism.
According to a first aspect of the present invention there is provided an actuating lever for a disc brake, comprising an elongate member, one end of which member is adapted to be, in use, engaged by brake applying means, the other end region of the member having a cam section with a part cylindrical curved surface having a longitudinal axis extending through the center of curvature of the surface, transversely of the longitudinal axis of the elongate member, the other end region also having a part cylindrical channel formed therein in a region separate from the part cylindrical curved surface, with an elongate cylindrical force transmitting member located therein and extending radially outwardly of the channel, the cylindrical force transmitting member being parallel to the longitudinal axis of the part cylindrical surface, and having opposite end regions which are located in recesses formed in the lever at opposite ends of the channel to thus retain the force transmitting member in position on the lever.
In a preferred embodiment of the present invention a bearing e.g., a proprietary PVDF, PTFE and lead composition, is located between the cylindrical force transmitting member and the channel to allow the force transmitting member to rotate therein about its longitudinal axis. Further, a series of teeth are provided adjacent to the cam section along a path following the cylindrical cam section, these teeth, in use, being used to operate an adjuster to cater for pad wear.
According to a further aspect of the present invention there is provided an actuating lever for a disc brake comprising an elongate member, one end of which member is adapted to be, in use, engaged by brake applying means, the other end region of the elongate member having two cam sections which extend laterally in opposite directions from the elongate member, each cam section having a part cylindrical surface, the cylindrical surfaces being coaxial with each other, with their common longitudinal axis extending transversely on the longitudinal axis of the elongate member, each cam section having a part cylindrical channel formed in a region separate from the part cylindrical surface thereof, an elongate cylindrical force transmitting member being located in each the channel and extending radially outward therefrom, the axis of the respective channels and cylindrical force transmitting members being parallel to the longitudinal axis of the part cylindrical surfaces, with the cylindrical force transmitting members each having opposite end regions which are located in recesses formed in the lever at opposite ends of the channels to thus retain the respective force transmitting members in position in their respective channels in the lever.
In a preferred embodiment, one recess is formed as a cylindrical blind bore in the elongate member, and the other recess for retaining a force transmitting member is formed as a cylindrical bore in an extension of the cam section, with the cylindrical bore and the blind bore being coaxial with each other and with the channels. Thus, on assembly, a cylindrical force transmitting member can be passed axially through the cylindrical bore along the channel and engaged in the blind bore, one end region being thus retained by the blind bore and the other end of the force transmitting member then being retained in the cylindrical bore. During transit and initial assembly a plug e.g., a plastic or rubber plug, can be located in the cylindrical bore to close the bore and hold the force transmitting member in position.
Further, the lever arm i.e., the elongate member, is preferably formed as a generally triangular structure with the one end region of the elongate member being located at an upper corner and the lateral cam sections projecting in opposite directions from each of the lower two corners. In this generally triangular construction, an aperture is formed in approximately the central region for the central l

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