Anti-rotation lock for fastener bolt
AssigneeThe United States of America as represented by the Secretary of the Army
InventorRobert B. de Claire
Life of this patent
Estimating the term…
Abstract
An improved lock washer locatable between the head of a fastener bolt and e work being fastened. The lock washer includes a retractable blade having a "hinged" connection with the main plate area of the washer. During thread-in operations the blade assumes a non-obstruct position. When the bolt is torqued to its seated position the blade is engaged with a shoulder formed on the head of the bolt, thereby positively obstructing the bolt from unthreading movement. If it should be necessary to unthread the bolt the blade can be manually pried or forced to a non-obstructing position. The blade has a positive lock action that does not depend on frictional forces.
Claims1
In an engine-transmission assembly wherein the transmission includes a bell-like housing having a peripheral flange mating with an end face of the engine, the mating areas of the transmission flange and engine face having a number of aligned holes spaced therealong, a bolt having a threaded shank portion extending through each set of aligned holes for thereby rigidly connecting the engine and transmission together, each bolt having a head spaced outwardly from the exposed face of the transmission flange, and a washer associated with each bolt for preventing unthreading thereof from the transmission-engine assembly;
- each washer including a main plate section underlying the bolt head, and a blade section extending outwardly from said main plate section beyond the peripheral edge of the transmission flange;
- the main plate section of the washer including a wing area (23 or 25) extending along the surface of the transmission flange with one edge thereof located in near proximity to the transmission bell surface, to thereby prevent the washer from turning around the bolt axis;
- the head of each bolt having a non-circular outline defining a system of wrench flats on the bolt head side surfaces defing corners therebetween the blade section of each washer having a circular aperture with a diameter slightly greater than the diametrical spacing of the bolt head flats but less than the diametrical spacing of the corners between the flats;
- the washer being formed of a material that permits the blade section to be moved in hinge-like fashion around its connection with the main plate section, whereby the circular aperture axially aligns with the bolt head;
- the dimension of the circular aperture and the material of the washer enabling the blade section to be hammered down and around the bolt head so that the bolt head corners defined by the aforementioned flats pierce the blade material, thereby preventing relative rotation of the bolt and washer.
Dependencies are inferred from the claim text.