Geometrical instruments – Distance measuring – Opposed contacts
Reexamination Certificate
1999-02-18
2001-04-17
Gutierrez, Diego (Department: 2859)
Geometrical instruments
Distance measuring
Opposed contacts
C033S811000, C033S610000
Reexamination Certificate
active
06216357
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention generally relates to measurement instruments, and more specifically to an adjustable gage for measuring the inside diameter of a brake drum of a vehicle while a wheel is mounted on the vehicle.
2. Description of the Prior Art
Brake drums on motor vehicles have an internal cylindrical surface arranged to be engaged by brake shoes or pads during braking. Because braking action relies on friction the brake shoes or pads as well as the cylindrical surface of the brake drums slowly wear with use and need to be adjusted or replaced in order to provide the necessary tolerances to provide reliable braking action. However, while the condition of the brake shoes or pads can frequently be established by visual inspection, it is more difficult to establish whether the brake drums fall within required specifications without utilizing a measuring instrument, such as a brake drum gage. One such brake drum gage is disclosed in U.S. Pat. No. 5,465,501 assigned to the assignee of the present application.
The problem addressed by the aforementioned U.S. Pat. No. 5,464,501 is the need to avoid inaccurate measurements resulting from improper positioning of the brake drum gage within the brake drum. The disclosed gage is provided with a plurality of pairs of adjustable depth stops that are movable along the jaws or arms of the gage which support the pointed anvils that contact the internal or external cylindrical surface to be measured. By adjusting selected depth stops to either retracted or extended positions, one pair of depth stops can be arranged to engage a rim or abutment surface of a cylindrical member, such as a brake drum, thereby ensuring that the measurement anvils will contact diametrically opposite sides of the cylindrical surface to be measured along a plane which is substantially normal to the axis of the cylindrical surface. This avoids oblique misalignments of the gage and ensures more precise measurements. However, the brake drum with adjustable depth stops disclosed in this patents is essentially a two-dimensional brake drum gage in which the jaws or arms are planar members essentially arranged in a common plane of the bar on which they are mounted. While the gage is suitable for providing very accurate measurements of a drum when the wheel is removed from the vehicle, and there are no encumbrances in the way for making the measurements on the brake drum, a gage that is two dimensional is not practical for making brake drum measurements while the wheel is mounted on the vehicle due to the presence of undercarriage and other components or parts that block free access to the cylindrical surface of the brake drum. The major obstacle or encumbrance that typically prevents such access is the wheel axle and axle tube which generally has a large diameter and extends transversely across the vehicle between opposing wheels. It is difficult, in the presence of such an axle tube, as well as other undercarriage components or parts, to position a two dimensional brake drum gage which properly aligns the measuring anvils at diametrically opposite points of the brake drum cylindrical surface, as discussed in the aforementioned patent, and the same time orients the brake drum gage in a position that makes it possible for the mechanic to read the dimensional markings or indications on the gage.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide an adjustable drum gage which does not have the disadvantages inherent in prior art drum measurement gages.
It is another object of the present invention to provide an adjustable gage for conveniently and accurately measuring the diameter of the cylindrical surface of a body such as a brake drum in the presence or absence of encumbrances in the region of the cylindrical surface such as an axle tube or other undercarriage components or parts in the proximity of a brake drum.
It is still another object of the present invention to provide an adjustable brake drum gage as aforementioned which is simple in construction and inexpensive to manufacture.
It is yet another object of the present invention to provide an adjustable gage as suggested in the previous objects which allows precise measurements to be obtained both by expert mechanics or technicians as well as those with lesser experience.
It is a further object of the present invention to provide a brake drum gage of the type under discussion which can be quickly and conveniently calibrated for zero spacing between the measurement anvils.
In order to achieve the above objects as well as others which will become apparent hereafter a brake drum gage in accordance with the present invention is used for measuring the inside diameter of a brake drum of a vehicle with the wheels mounted on the vehicle in the presence of an axle tube or other undercarriage components or parts. The brake drum gage comprises an elongate generally flat bar having proximate and remote ends and defining an elongate axis in a reference plane. A fixed element is fixedly mounted at said proximate end of said bar and a remote element is movably mounted on said bar for movements along said bar between said proximate and remote ends for adjusting the spacing between said elements. Each element includes a generally V-shaped arm including an upright portion generally parallel to said reference plane and an angled portion inclined in relation to an associated upright portion and said reference plane. A fixed anvil is provided on said angled portion of said fixed element and has a tip extending beyond said fixed element in a direction of said remote end of said bar and a movable anvil on said angled portion of said movable element and having a tip extending beyond said movable element in a direction of said proximate end of said bar. Indicating means is provided for providing an indication of the distance between said tips of said anvils along a direction substantially parallel to said axis, said anvils on said angled portions being positionable at diametrically opposite positions on the inside cylindrical surface of a brake drum while said bar is spaced inwardly from said drum and clears the axial tube and other undercarriage components or parts of the vehicle. In this manner the drum gage can be used to measure brake drums without removing the wheels from the vehicle.
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Offiler Stephen
Victor Richard
Central Tools, Inc
Guadalupe Yaritza
Gutierrez Diego
Lackenbach Siegel Marzullo Aronson & Greenspan
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