Magnetic compass
OwnerAlbert M. DeGaeta, Edythe C. DeGaetainventors
Life of this patent
Estimating the term…
Abstract
A magnetic compass comprises a case having a transparent cover and a magnetic compass card having a hub, which is rotatably supported on a central shaft projecting up from the base of the case by bearings comprising a thrust bearing between the hub and the upper end of the shaft and a radial bearing between the hub and a portion of the shaft spaced downwardly from the upper end. The radial bearing comprises a bearing ring set in a central recess in the hub and a full circle of small balls between the bearing ring and the shaft. In one embodiment there are two such radial bearings located one below the other. The bearings rotatably support the compass card on the shaft and retain it approximately perpendicular to the shaft even if the case is tilted.
Claims14
A magnetic compass comprising a case having a peripheral wall, a base and a transparent cover defining a card-receiving cavity, a fixed vertical shaft projecting up from said base centrally of said cavity and having an upper end below said cover, a compass card received in said cavity for rotation therein on said shaft, said compass card having a hub and magnetic means for orienting said card relative to terrestrial magnetic lines of force, and bearing means in said hub for rotatably supporting said card on said shaft, said bearing means comprising thrust bearing means engaging said upper end of said shaft to support said card vertically, and radial bearing means rotatably engaging said shaft below said upper end to position said card radially and to retain it approximately perpendicular to said shaft, said radial bearing means comprising an anti-friction bearing comprising an annular bearing race in said hub of said compass card formed of hard, strong, durable material and having a smooth circular cylindrical inner surface coaxially encircling and radially spaced from said shaft, a full circle of small precisely spherical balls of hard, strong, durable material between said bearing race and said shaft and flat annular end plates at opposite ends of said bearing race for retaining said balls in a circle, said balls being retained solely by said shaft, bearing race and end plates.
A magnetic compass comprising a case having a peripheral wall, a base and a transparent cover defining a card-receiving cavity, a fixed vertical shaft projecting up from said base centrally of said cavity and having an upper end below said cover, a compass card received in said cavity for rotation therein on said shaft, said compass card having a hub and magnetic means for orienting said card relative to terrestrial magnetic lines of force, and bearing means in said hub for rotatably supporting said card on said shaft, said bearing means comprising thrust bearing means rotatably engaging said shaft below said upper end to position said card radially and to retain it approximately perpendicular to said shaft, said radial bearing means comprising two anti-friction bearings disposed axially of one another on said shaft, each of said anti-friction bearings comprising an annular bearing race in said hub of said compass card formed of hard, strong, durable material and having a smooth circular cylindrical inner surface coaxially encircling and radially spaced from said shaft, a full circle of small precisely spherical balls of hard, strong, durable material between said bearing race and said shaft and flat annular end plates at opposite ends of said bearing race for retaining said balls in a circle, said balls being retained solely by said shaft, bearing race and end plates.
A magnetic compass comprising a case having a peripheral wall, a base and a transparent cover defining a card-receiving cavity, a vertical shaft projecting up from the base central of said cavity and having a pointed upper end below said cover, a balanced compass card received in said cavity for rotation therein on said shaft, said compass card having a hub with a central downwardly opening recess and magnetic means mounted on said hub for orienting said card to terrestrial magnetic lines of force, and bearing means in said hub for rotatably supporting said card on said shaft, said bearing means comprising a bearing block of hard low-friction material set in an upper portion of said hub and having on its lower side a cavity receiving said pointed upper end of said shaft and anti-friction radial bearing means rotatably engaging the shaft below the upper end, said radial bearing means comprising axially spaced flat annular end plates set tightly in said recess of said hub, a bearing ring of hard, strong, durable material sandwiched between said end plates and having a circular cylindrical bearing surface uniformly spaced radially from said shaft and a full circle of small precisely spherical balls of hard, strong, durable material between said end plates and between said bearing ring and said shaft, said bearing rings being of material having a substantially higher modulus of elasticity than material of said hub.
A magnetic compass comprising a case having a peripheral wall, a base and a transparent cover defining a card-receiving cavity, a vertical shaft projecting up from the base centrally of said cavity and having an upper end below said cover, a balanced compass card received in said cavity for rotation therein on said shaft, said compass card having a hub with a central downwardly opening recess and magnetic means mounted on said hub for orienting said card to torrestrial lines of force, and bearing means in said hub for rotatably supporting said card on said shaft, said bearing means comprising thrust bearing means in an upper portion of said hub engaging the upper end of said shaft to support said card vertically, and anti-friction radial bearing means set in said recess of said hub and rotatably engaging said shaft below its upper end, said radial bearing means comprising in sequence a first flat annular end plate, a first bearing ring set against said first end plate, a second flat annular end plate set against said first bearing ring, a second like bearing ring set against said second end plate and a third like flat annular end plate set against said second bearing ring, a first full circle of small balls between said first bearing ring and said shaft and between said first and second end rings and a second full circle of small balls between said second bearing ring and said shaft and between said second and third end rings, said hub closely confining said end plates and bearing rings to hold them in assembled rotation, said shaft, end plates, bearing rings and balls being of hard, strong, durable material and said hub being of material having a modulus of elasticity substantially lower than that of the material of said bearing rings and end plates.
Dependencies are inferred from the claim text.