Tools – Wrench – screwdriver – or driver therefor – Handle clutched to head
Reexamination Certificate
2002-05-17
2003-04-08
Smith, James G. (Department: 3723)
Tools
Wrench, screwdriver, or driver therefor
Handle clutched to head
C081S058400, C081S063100, C192S043200
Reexamination Certificate
active
06543315
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is related to an improved ratchet structure of a screwdriver in which the ratchet mechanism includes a left dog and a right dog. A left and a right projecting sections of a post are cooperatively inlaid in left and right notches of the middle sections of the left and right dogs. The left and right projecting sections serve as supports for the left and right dogs, whereby the ratchet screwdriver can be more truly operated and the torque value of the ratchet screwdriver is increased.
FIGS. 6 and 7
show a conventional ratchet screwdriver. The front end of the handle
81
has a seat body
82
. A stem
83
is fitted in the seat body
82
. A section of the stem
83
in the seat body
82
is a toothed section
831
. The seat body
82
is formed with a cavity
821
in which a ratchet mechanism
9
is disposed. The ratchet mechanism
9
has two dogs
91
. The wall of the cavity
821
is formed with two dented sections
822
in which the two dogs
91
are planted. The dented sections
822
serve as supports for the dogs
91
, whereby the dogs
91
can swing about the sections abutting against the dented section
822
. Two springs
92
are respectively disposed between two lateral walls of the cavity
821
and the two dogs
91
. The springs
92
push the dogs
91
to engage with the toothed section
831
of the stem
83
. A drive block
93
is disposed between the two dogs
91
. One end of the drive block
93
extends out of the seat body
82
to couple with an outer collar
84
fitted around the seat body
82
. By means of turning the outer collar
84
, the drive block
93
is driven and rotated to respectively push and disengage the dogs
91
from the toothed section
831
. Accordingly, the rotational direction of the stem
83
driven by the seat body
82
can be controlled.
The sections of the dogs
91
abutting against the dented sections
822
serve as supporting points for the dogs
91
. The free ends of the dogs
91
engaged with the toothed section
831
of the stem
83
are opposite to the sections abutting against the dented sections
822
. Accordingly, the arm of resistance of the dogs
91
engaged with the toothed section
831
is considerably long. Therefore, the dogs
91
are easy to deform or break when suffering too great force. Under such circumstance, the ratchet mechanism
9
will fail. Furthermore, the dogs
91
have considerable lengths and swing about the sections abutting against the dented sections
822
. Therefore, the drive block
93
needs to push the dogs
91
to swing by a considerable amplitude so as to disengage from the toothed section
831
. In the case that the drive block
93
is worn or the dogs
91
are deformed, it often takes place that the dogs
91
cannot be totally disengaged from the toothed section
831
of the stem
93
. As a result, the screwdriver can be hardly truly operated.
SUMMARY OF THE INVENTION
It is therefore a primary object of the present invention to provide an improved ratchet structure of a screwdriver in which the left and right dogs of the ratchet mechanism are respectively disposed in the left and right splits defined between the stop wall and the post integrally projecting from the seat body. The post is formed with a left and a right projecting sections respectively corresponding to the left and right dogs and inlaid in the left and right notches of the middle sections of the left and right dogs. Accordingly, the post serves to support the left and right dogs, whereby the left and right dogs can swing about the projecting sections inlaid in the left and right notches of the middle sections of the left and right dogs. Therefore, the swinging amplitude of the left and right dogs is reduced and the ratchet screwdriver can be more truly operated.
It is a further object of the present invention to provide the above ratchet structure in which the left and right projecting sections of the post inlaid in the left and right notches of the middle sections of the left and right dogs serve as supports for the left and right dogs. Therefore, the arm of resistance of the left and right dogs engaged with the toothed section of the stem is shortened. Therefore, the left and right dogs can bear greater resistance and the torque value of the ratchet screwdriver is increased.
The present invention can be best understood through the following description and accompanying drawings wherein:
REFERENCES:
patent: 2803980 (1957-08-01), Vogel
patent: 4541310 (1985-09-01), Lindenberger
patent: 5520073 (1996-05-01), Bakula et al.
patent: 5531139 (1996-07-01), Fanchang et al.
patent: 5535648 (1996-07-01), Braun et al.
patent: 5570616 (1996-11-01), Thompson et al.
Shakeri Hadi
Smith James G.
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