Unidirectional ratchet wrench

Details Unidirectional ratchet wrench Unidirectional ratchet wrench

2002-01-07

2003-03-11

Smith, James G. (Department: 3723)

Tools

Wrench, screwdriver, or driver therefor

Handle clutched to head

C081S058000, C081S058400, C192S043200

Reexamination Certificate

active

06530296

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a unidirectional ratchet wrench, and more particularly to a unidirectional ratchet wrench that has excellent torsion-resisting force.
2. Description of Related Art
With reference to
FIGS. 6 and 7
, a conventional unidirectional ratchet wrench, invented by the applicant of this invention, is essentially composed of a wrench body (
60
) and a socket assembly.
The wrench body (
60
) has a toothed cavity (
61
) defined in one end of the wrench body (
60
) to receive the socket assembly in the toothed cavity (
61
). Multiple teeth (
62
) are formed longitudinally on an inner periphery of the toothed cavity (
61
). Each tooth (
62
) has an inclined face (
621
) and an upright face (
623
), and the inclined faces (
621
) of the teeth (
62
) are all arranged in the same direction.
The socket assembly is composed of a socket wheel (
70
), two pawls (
74
) and a split ring (
76
). A socket (
71
) is defined in the socket wheel (
70
) and is adapted to engage a nut or the similar fitting. Two pawl recesses (
72
) are defined longitudinally in an outer periphery of the socket wheel (
70
) to hold the two pawls (
74
) inside, and a groove (
73
) is defined around in the outer periphery of the socket wheel (
70
) to receive the split ring (
76
). Each pawl (
74
) is a curved sheet with a tapered thickness and a slot (
741
) transversally defined in the central part of an outer periphery of the pawl (
74
). A locking end (
75
) is formed on a thin edge of each pawl (
74
), and a lever end (
751
) formed on a thick edge opposite to the thin edge of each pawl (
74
). When the two pawls (
74
) are inside the pawl recesses (
74
) of the socket wheel (
70
), the slots (
741
) of the pawls align with the groove (
73
) in the socket wheel (
70
) and have a special cut or orientation to allow the pawls (
74
) to rock inside. The split ring (
76
) resiliently holds the pawls inside the pawl recesses (
74
) and compresses the lever end (
53
) of the pawls (
74
) to make the locking end (
75
) of the pawls lever outwardly. Whereby, the split ring (
76
) provides a restitution force on the pawls (
74
) to make the pawls (
74
) mate with the teeth (
62
) and then to lock the socket wheel (
70
) with the wrench body (
60
). Additionally, two locking rings (
77
) are mounted on opposite openings of the toothed cavity (
61
) to hold the socket assembly inside the wrench body (
60
).
When the conventional unidirectional ratchet wrench operates, the wrench body (
60
) is rotated to make the locking ends (
751
) of the pawls (
74
) engage the straight faces (
623
) of the teeth (
62
). Then, the socket wheel (
70
) is twisted by the wrench body (
60
) and rotates with the wrench body (
60
) so that a nut inside the socket (
71
) is also rotated. When the wrench body (
60
) is rotated in the opposite direction, the locking ends (
751
) of the pawls (
74
) move along the inclined faces (
621
) of the teeth (
62
). Then, the socket wheel (
70
) does not rotate with the wrench body, and the wrench is in an idle running state.
However, the conventional unidirectional ratchet wrench has the following drawbacks:
1. The slot (
741
) in each pawl (
74
) has to be defined precisely in a special cut and orientation. Otherwise, the pawl (
74
) cannot be levered to engage the locking end (
75
) with the teeth (
61
) perfectly, and then the torsion-resisting force of the conventional unidirectional ratchet wrench is weak.
2. The torsion-resisting efficiency of the wrench is provided by the locking ends (
751
) of the pawls (
74
) and is uneven and insufficient. Therefore, the split ring (
74
) easily deforms when the torsional force is slightly exceeded.
To make the unidirectional ratchet wrench endurable, the present invention has arisen to mitigate and/or obviate the disadvantage of the conventional unidirectional ratchet wrench.
SUMMARY OF THE INVENTION
The main objective of the present invention is to provide a unidirectional ratchet wrench that has excellent torsion-resisting efficiency.
Further benefits and advantages of the present invention will become apparent after a careful reading of the detailed description with appropriate reference to the accompanying drawings.


REFERENCES:
patent: 1271671 (1918-07-01), Cooper
patent: 4796492 (1989-01-01), Liou
patent: 5878635 (1999-03-01), Hsieh
patent: 6357323 (2002-03-01), Chi et al.
patent: 3319-818 (1984-12-01), None

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