OVERSPEED INDICATOR FOR A ROTATABLE SHAFT

• US 3,807,348 A
• Filed: 05/24/1973
• Issued: 04/30/1974
• Est. Priority Date: 05/24/1973
• Status: Expired due to Term

• Current Assignee: Bernard N. Hill, James A. Perham
• Original Assignee: Bernard N. Hill, James A. Perham
• Inventors: Perham, James A., Hill, Bernard N.
• Primary Examiner(s): Capozi, Louis J.
• Application Number:
  US05/363,371
• Time in Patent Office: 341 Days
• Field of Search: 116/73,74,114,115 73/492,512,535,536,548,488 74/573,574
• US Class Current: 116/74
• CPC Class Codes: G01P 1/10 for indicating predetermined speeds
• CPC Class Codes: G01P 3/16 by using centrifugal forces of solid masses governors G05D13/10

Abstract

An overspeed indicator for a rotatable shaft comprises, in the example disclosed, a circular disc of inexpensive, frangible material such as chip board, paper board, or card board. The disc has a central, polygonal opening enabling it to be screwed onto a threaded end of a shaft as a temporary substitute for a rotatable member such as a grinding wheel normally supported on it. The disc also has an off-center opening within which there is a cantilever overspeed tab integral with the body of the disc extending radially inwardly from an outer peripheral edge portion of the disc and parallel to the fibrous grain of the frangible material. The tab is designed to fly off, harmlessly, when rotated at a sufficiently high speed above the normal rating of the grinding wheel to indicate it would be hazardous to use the wheel at that speed. Non-fibrous material having little or no grain may be substituted for chip board, one example being given as '"'"''"'"''"'"''"'"'STYROFOAM'"'"''"'"''"'"''"'"' foamed polystyrene sheet material.

Claims

1. An overspeed indicator for a rotatable shaft comprising:

a disc-like body of frangible material having means to attach said body to the shaft for rotation therewith about a common axis;

said body having a weakened portion defining a tab which is dislocatable by centrifugal force in response to rotation above a predetermined speed.

2. An overspeed indicator for a rotatable shaft according to claim 1 in which said weakened portion includes an off-center opening near the periphery of the body, said frangible material is chip board, and said tab is a cantilever member integral with said body in said opening and extends radially inwardly toward the center of the body.

3. An overspeed indicator for a rotatable shaft according to claim 2 in which said tab is parallel to the fibrous grain of the chip board material.

4. An overspeed indicator for a rotatable shaft according to claim 1 in which said tab is defined by a generally U-shaped opening in said body having open arm portions pointing radially outwardly from the center of rotation of the body to thereby connect the tab and body across a base portion between the tips of said open arm portions and the outer periphery of the body.

5. An overspeed indicator for a rotatable shaft according to claim 1 in which said means comprises a polygonal center opening adapted to be screwed onto a threaded shaft.

6. An overspeed indicator for a rotatable shaft comprising:

a flat, disc-like body of frangible material having means for assembling on said shaft for rotation about a common axis;

said body having an off-center opening;

a tab in said off-center opening having a base portion integral with the periphery of the body at the outer portion of said opening and extending radially inwardly toward the center of said body;

said tab and base portion having selected dimensions enabling said tab to break off by centrifugal force in response to rotation in a predetermined speed range.

7. An overspeed indicator for a rotatable shaft according to claim 6 in which said means comprises has a center opening for said shaft.

8. An overspeed indicator for a rotatable shaft according to claim 6 in which said frangible material is chip board.

9. An overspeed indicator for a rotatable shaft comprising a disc made of chip board sheet material having a continuous circular periphery;

said disc being formed with a central polygonal opening adapted to be screwed onto a threaded end of a shaft for rotation therewith about a common axis;

said disc being formed with an off-center opening adjacent the periphery and having within said opening a cantilever tab integral with the disc and extending radially inward from the outer peripheral portion of said disc parallel to the fibrous grain of the chip board sheet material; and

said tab being dislocatable by centrifugal force in a predetermined speed range depending on the dimensions of the tab and of said peripheral portion and the strength of the said chip board sheet material.

10. An overspeed indicator for a rotatable shaft comprising:

a body having means to attach said body to the shaft for rotation therewith about a common axis;

said body having a portion thereof which is dislocatable by centrifugal force in response to rotation above a certaiN speed.