Brakes – Wheel – Transversely movable
Reexamination Certificate
1996-10-15
2001-04-10
Graham, Matthew C. (Department: 3613)
Brakes
Wheel
Transversely movable
C188S341000
Reexamination Certificate
active
06213264
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to an improved sealing and support arrangement for the camshaft of a cam brake system.
Cam brakes arc used to brake heavy vehicles such as trucks, by moving brake linings into contact with a brake drum upon rotation of a cam. The cam is typically in the form of an “S” shape. The cam rotates to force rollers radially outwardly, which then move the brake linings into contact with the drum. A camshaft, which rotates the cam, is rotated by an air brake actuator, typically through a connection with a slack adjuster. The camshaft must withstand very high forces as it is rotated to actuate the brake, and thus must be securely and properly mounted within its housing. In addition, lubrication of the camshaft to insure proper rotation is also necessary. In the prior art, seals and bearings have been provided between the camshaft, its housing and the slack adjuster; however, the seals and bearings have not always adequately mounted and sealed the camshaft. Rather, prior art camshafts have required frequent maintenance.
In addition, the connection between the slack adjuster and the camshaft has presented some difficulties. A large amount of rotational force is passed between the two members. Proper position and adequate sealing are also important at this connection, and yet sometimes difficult to achieve.
SUMMARY OF THE INVENTION
A disclosed embodiment of this invention includes a camshaft mounted within a housing, and provided with unique seals at each axial end. In addition, the camshaft is provided with specially machined surfaces to properly position its seals and bearings.
The camshaft is preferably provided with two bearings, with the bearing mounted closest to the slack adjuster being smaller than the outer bearing. The camshaft locations which support the bearings are provided with surface treatment, only at the location of contact within the bearing. In this way, the invention reduces the amount of material that must be surface treated, thus reducing cost.
In addition, the camshaft has a relatively large outer diameter at one end, near the cam, then moves to smaller diameters in a direction from the cam and towards the slack adjuster. In this way, the camshaft may be moved through the housing and into the bearings and seals with little difficulty. The progressively larger portions of the camshaft will move through the larger seals, bearings, etc., until the proper sized portion comes into alignment with the seal, bearing, etc. This feature of the invention provides improved assembly characteristics.
In a preferred embodiment of this invention, a first seal is placed between the camshaft and the housing at the cam end. The first seal has a lip contacting the camshaft, and a second lip extending radially outwardly to contact a radially outward surface of the camshaft housing. The outer seal prevents dirt, dust or other impurities from entering the housing. This first seal preferably also includes a bearing washer contacting the cam to provide a thrust washer surface for the cam. The first seal preferably does not rotate with the camshaft, but remains fixed with the camshaft housing. This seal, in combination with other seals at the other end of the camshaft housing, insure a camshaft and housing arrangement that is virtually maintenance free during the expected life of the brake system. The system is initially lubricated and the seals prevent leakage out of the housing. The seals prevent ingress of impurities to provide a dirt free environment within the camshaft housing such that no maintenance should be necessary.
In addition, the connection between the slack adjuster and the camshaft is also provided with seals. These seals insure that the lubrication between these two members also enjoys an unusually long life. Preferably seals are provided at each end of the connection between the camshaft and the slack adjuster.
In addition, the seals between the slack adjuster and the camshaft are each associated with washers which assist in positioning the slack adjuster on the camshaft. An outer snap ring abuts an outer washer holding the slack adjuster against the outer end of the camshaft housing. A second washer is positioned intermediate the camshaft housing and the slack adjuster, and provides a thrust washer surface. The combined washers provide proper positioning of the slack adjuster on the camshaft.
These and other features of the present invention can be best understood from the following specification and drawings, of which the following is a brief description.
REFERENCES:
patent: 3076531 (1963-02-01), Hanley et al.
patent: 3367458 (1968-02-01), Self et al.
patent: 3368648 (1968-02-01), Brownyer
patent: 3497037 (1970-02-01), Deibel
patent: 3677374 (1972-07-01), Newstead et al.
patent: 4476968 (1984-10-01), Urban et al.
patent: 4905800 (1990-03-01), Mathews
patent: 4981200 (1991-01-01), Gee
patent: 5044475 (1991-09-01), Clark
patent: 5062506 (1991-11-01), White
patent: 40 34 359A1 (1992-04-01), None
patent: 03 06 851A2 (1989-03-01), None
patent: 04 08 254A1 (1991-01-01), None
patent: WO96/25313 (1996-08-01), None
Dettloff David J.
Edwards David J.
Walker Donald G.
Graham Matthew C.
Howard & Howard
Meritor Heavy Vehicle Systems L.L.C.
LandOfFree
Sealing arrangement for brake camshaft does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Sealing arrangement for brake camshaft, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Sealing arrangement for brake camshaft will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2521875