Brake drum and disc micrometer

• US 3,889,378 A
• Filed: 06/28/1973
• Issued: 06/17/1975
• Est. Priority Date: 06/28/1973
• Status: Expired due to Term

• Current Assignee: Hein-Werner Corporation
• Original Assignee: William J. Senecal
• Inventors: Senecal, William J.
• Primary Examiner(s): Aegerter, Richard E.
• Assistant Examiner(s): Little, Willis
• Application Number:
  US05/374,684
• Time in Patent Office: 719 Days
• Field of Search: 33/143R,147K,178R,18AT,164C,164D,147T,147J,147G,159,163,165,158
• US Class Current: 33/610
• CPC Class Codes: G01B 5/0028 Brakes, brakeshoes, clutches

Abstract

A micrometer for measuring the inside diameter of brake drums and the thicknesses of brake discs includes a calibrated rod and a fixed sleeve member rigidly attached to one end of said rod. An adjustable contact pin having a machined contact surface at both ends is threadably engaged in the fixed sleeve member and is translatably mounted in a manually rotated dial. Calibrations on the dial correspond to the amount of linear movement experienced by the contact pin when the dial is rotated. A movable sleeve is also mounted on the calibrated rod and carries a set screw for positioning the sleeve on the rod by engaging one of a row of regularly spaced holes drilled in the rod for this purpose. Fixed contact pins carried by the movable sleeve are mounted in axial alignment with the adjustable contact pin on the fixed sleeve and point in opposite directions with respect to each other. Two sets of calibrations on the rod are in registry with the regularly spaced holes and correspond to the distances between the inner and outer contact surfaces of the adjustable and fixed contact pins. Inside or outside distances may thus be measured by first adjusting the calibrated dial to zero, placing the appropriate fixed contact pin in abutting relation to the workpiece, adjusting the movable sleeve to the closest corresponding calibration on the rod and then rotating the calibrated dial to bring the inside or outside contact surface of the adjustable contact pin into engagement with the workpiece.

Claims

1. A brake drum and disc micrometer comprising an elongated rod, means fixedly secured to said rod and having an arm extending therefrom, first contact pin means movably supported in said arm parallel to said rod and having an outer end for engaging the inner surface of a brake drum and an inner end for engaging the outer surface of a brake disc, calibrated means for axially adjusting said pin means in said arm and for indicAting the extent of movement thereof from a normal or '"'"''"'"''"'"''"'"'zero'"'"''"'"''"'"''"'"' position relative to the arm, a sleeve supported on said rod for movement thereon to predetermined fixed positions and having an arm extending therefrom, second contact pin means fixedly secured to the last mentioned arm in axial alignment with the first pin means and also having outer and inner ends for contacting the inner and outer surfaces of brake drums and discs respectively, the total length of said two contact pin means being known, the said rod is provided with a pair of calibrated scales along its length for reading brake disc thickness and brake drum inside diameter respectively with reference to the position of the sleeve on the rod, the disc thickness scale having a starting calibration indicative of the predetermined distance apart of the inner ends of the two contact pin means at one predetermined fixed position of the sleeve and with the first contact pin means set at its calibrated '"'"''"'"''"'"''"'"'zero'"'"''"'"''"'"''"'"' position, and the drum diameter scale having a coincident starting calibration which is larger than the starting calibration on the disc scale by the said known total length of said contact pin means.

2. A micrometer as defined in claim 1 wherein said first contact pin means comprises a single pin threaded into its associated arm, and the means for axially adjusting said first contact pin means comprises a cylindrical dial around the pin rotatably supported in said associated arm and having peripheral calibrations referenced to a point on said associated arm.

3. The micrometer of claim 2 and wherein said contact pin comprising the first pin means has an axial series of calibrations provided thereon corresponding to the said dial cylinder whereby a vernier reading is provided in combining the visible calibrations on said first pin means with the dial calibrations referenced to said point on said associated arm.

4. The drum and disc micrometer as set forth in claim 1 wherein both of said arms are adapted to rest on the rim of a brake drum while supporting the first and second contact pin means for engagement with the inner surface of the drum in diametrically opposed locations.

5. The micrometer of claim 1 wherein the second contact pin means comprises a pair of pins threaded into the sleeve arm to extend in opposite directions, and wherein means are provided to retain the said pair of pins against axial movement after they have been located in preselected positions in said sleeve arm.