Machine element or mechanism – Elements – Pawls and ratchets
Patent
1991-07-15
1993-07-13
Herrmann, Allan D.
Machine element or mechanism
Elements
Pawls and ratchets
74577R, 74577M, 74578, 188 822, 188 827, G05G 506
Patent
active
052263428
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a locking device of the rachet-type capable of limiting the movement of a moving component between two extreme stop positions.
Various ratchet locking devices are known. Two conventional types are shown in FIGS. 1 and 2. The moving component of the device shown in FIG. 1 is constituted by a rack comprising a uniform succession of triangular-shaped notches on one side which are disposed so that together they define a saw-tooth profile. The means for locking the above rack is constituted by a sharp finger for engaging in one of the notches of the rack under drive acting in the direction of the arrow shown in FIG. 1. The finger is held in its locking position by a spring mounted in a prestressed condition to urge the finger against the bottom of the triangular profile of a notch. Passage from one tooth to the next takes place suddenly after the locking finger has slid over the sloping side of the preceding notch. Travelling from the first notch to the last notch defines the maximum stroke of the rack in the above-defined direction. In this case, it is clear that in order to return to the initial position, it is necessary to apply external action to the device so as to disengage the locking finger from the last notch and to slide the rack so as to bring the first notch into coincidence with the locking finger.
As for the device shown in FIG. 2, the moving component thereof comprises a special type of rack which is provided with a succession of notches on one side having the shape of circular arcs (which are slightly smaller than the corresponding semi-circumference), which notches are uniformly spaced apart along one side of the rack. The locking means for the rack is constituted by a ball for resiliently engaging in a notch and remaining therein under drive from a spring, which spring is likewise prestressed, with the ball remaining in a notch until a force is applied in either direction as shown by the double-headed arrow of FIG. 2.
The locking device shown in FIG. 1 is of the "one-way" type whereas the locking device of FIG. 2 is of the "two-way" type for which the direction of motion of the rack is reversed automatically at the end of its stroke without requiring the locking means to be deactivated. However, the FIG. 2 device suffers from the drawback that the load which may be applied thereto is limited because it is difficult to actuate the rack if the prestress of the spring is too high.
An object of the present invention it thus to provide a two-directional type ratchet locking device capable of limiting the motion of a moving component between two extreme stop positions in which the load that can be applied is not limited by the prestress of the spring acting on the locking means (ratchet) and in which it is therefore easy to put the moving component into action, i.e. the motion of the moving component reverses automatically without there being any need to unlock the ratchet to allow the moving component to go to its opposite extreme stop position when the direction of application of the applied load reverses: in the context of the present invention this condition is expressed by saying that the device is an "automatically-unlocking" device (with the ratchet naturally being unlocked); which device should also be capable of detecting intermediate positions between the two extreme stop positions through which the moving component passes, with such detection having no effect on the motion of said moving component and being independent of its direction of movement; and, naturally, it should require no external action to activate locking of the moving component when it reaches one of its extreme stop positions (i.e. the device is self-locking).
The present invention provides a moving component for moving between first and second extreme stop positions, and including at least a first notch and a second notch formed in the moving component symmetrically about an axis of symmetry thereof and in positions corresponding to its extreme stop positions, with the bottoms of said not
REFERENCES:
patent: 41574 (1864-02-01), Groel
patent: 275657 (1883-04-01), How
patent: 839957 (1907-01-01), Reiss
patent: 1140167 (1915-05-01), Kolb et al.
patent: 1824515 (1931-09-01), Traphagen
patent: 2871719 (1959-02-01), Hooker
patent: 3590656 (1971-07-01), Lloyd
patent: 4468005 (1984-08-01), Nakamura
Agence Spatiale Europeenne
Herrmann Allan D.
Trousdell William O.
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