Tools – Wrench – screwdriver – or driver therefor – Handle clutched to head
Reexamination Certificate
2001-07-09
2003-12-23
Smith, James G. (Department: 3723)
Tools
Wrench, screwdriver, or driver therefor
Handle clutched to head
C192S043200
Reexamination Certificate
active
06666112
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a switching arrangement for a reversible ratchet-type wrench to provide reliable ratcheting and to allow easy assembly and manufacture.
2. Description of the Related Art
Several factors are considered in designing wrenches and spanners, including improving the torque-bearing capacity, providing as many teeth as possible for the drive member, and providing an easy-to-manufacture structure. U.S. Pat. No. 2,957,377 issued to Hare on Oct. 25, 1960 discloses a reversible ratchet type wrench comprising a body
10
having a handle
11
and a head
12
. A cap
39
and an annular wall
44
are provided to upper side and lower side of the head
12
, respectively. Yet, this increases the assembly time and the manufacture cost and adversely affects the appearance. A shifting lever
35
is retained in place by a spring
33
that is located in a cylindrical opening
34
. Nevertheless, formation of the cylindrical opening
34
that extends upward at an incline is relatively difficult. In addition, formation of the cavity
16
having converging straight sides
17
,
18
which diverge in the direction of the periphery of rotatable member
14
requires expensive and accurate computer-numeric-control (CNC), which further results in an increase in the cost together with a low production rate. This is why such a reversible ratchet type wrench is hardly seen in the market.
FIGS. 13 and 14
illustrate another conventional ratchet type wrench comprising a handle
12
′ and a head
11
′. The head
11
′ is machined to form four consecutive compartments for receiving the drive member
20
′, the pawl
30
′ and the shifting lever
40
′, wherein three of the compartments can be formed by cutting, yet the remaining one must be machined by CNC. Further, the resultant head structure is relatively weak and thus has a poor torque-bearing capacity. In addition, the movement of the pawl
30
′ for changing ratcheting direction is found unreliable, as it is achieved via transmission of the hook end
442
′ of a spring
44
′ attached to the shifting lever
40
′.
FIG. 15
of the drawings illustrates a conventional wrench of the type having a handle B′ and a head in which a drive member A′ is rotatably received. A pawl D′ is slidably received in a transverse through-hole C′ in a web between the handle B′ and the head. However, an end of the pawl D′ extends beyond the transverse through-hole C′ and thus adversely affects operation of the wrench when used in a limited space. A two-pawl type wrench was proposed to solve this problem. As illustrated in
FIGS. 16 through 18
, the two-pawl type wrench includes a handle
1
′ and a head
11
′ extended from the handle
1
′. A drive member
2
′ is rotatably received in the head
11
′, a receptacle
121
′ is defined in a web
12
′ between the handle
1
′ and the head
11
′, and a spring-biased switch member
4
′ is mounted in a cavity
13
′ in the web
12
′. Two spaced pawls
3
′ are received in the receptacle
121
′ and are biased by two springs
6
′, respectively. A threaded end cap
5
′ is engaged with a threaded outer end of the receptacle
121
′ to enclose the pawls
3
′ and springs
6
′. As illustrated in
FIGS. 17 and 18
, the switch member
4
′ is turned to bias one of the pawls
3
′ to engage its teeth
31
′ with the drive member
2
′ to thereby change the ratcheting direction of the wrench. However, it was found that the switch member
4
′ cannot be reliably retained in place and thus tends to disengage from the cavity
13
′. In addition, the pawl
3
′ engaged with the drive member
2
′ is not engaged with an inner longitudinal wall that defines the transverse through-hole and that faces the drive member
2
′. As a result, the torque-bearing capacity of the wrench is poor. Furthermore, the outer pawl
3
′ (
FIGS. 17 and 18
) tends to be stuck when the threaded end cap
5
′ is mounted too close to the switch member
4
′. To the contrary, if the threaded end cap
5
′ is too far away from the switch member
4
′, the pawl
3
′ cannot be firmly engaged with the drive member
2
′. Further, the threaded end cap
5
′ tends to be disengaged from the drive member
2
′, as the former is in threading engagement with the threaded outer end of the receptacle
121
′.
FIGS. 19 through 21
illustrate another conventional wrench having a substantially V-shape transverse through-hole
25
′ in a web between a handle
20
′ and a head
21
′ thereof. The head
21
′ includes a compartment in which a drive member
22
′ is rotatably received. A spring-biased pawl
23
′ is received in each limb of the V-shape transverse through-hole
25
′. A switch member
30
′ includes a stem
35
′ pivotally received in a cavity
24
′ in the web and a thumb-piece
32
′ extending from the stem
35
′ for manual operation, thereby switching the switch member
30
′ between two positions corresponding to two opposite ratcheting direction of the wrench. The thumb piece
32
′ of the switch member
30
′ includes a downwardly facing receptacle
36
′ (
FIG. 21
) for receiving a spring
37
′ and a ball
38
′ that is biased by the spring
37
′ to be positioned in one of two positioning recesses
281
′ (
FIG. 20
) in a sector-like recessed area
28
′ (
FIG. 19
) of the web. The switch member
30
′ may be retained in place reliably. However, a C-clip
33
′ is required for mounting the switch member
30
′ in place, which adversely affects the aesthetically pleasing effect. In addition, processing of the sector-like recessed area
28
′ in the web and the V-shape transverse through-hole
25
′ is difficult. Mounting of the switch member
30
′ as well as the pawl
23
′ and associated springs
26
′ and threaded end caps
27
′ are troublesome and time-consuming. The sector-like recessed area
28
′ in the web results in an increase in the overall thickness of the wrench, which limits application of the wrench in limited spaces. The torque-bearing capacity was found poor, as only a portion of the pawl
23
′ meshed with the drive member
22
′ was supported by the inner wall of the V-shape transverse through-hole
25
′, as shown in FIG.
20
.
SUMMARY OF THE INVENTION
In accordance with the present invention, a reversible ratchet type wrench comprises:
a handle;
a head extended from the handle and including a hole, the handle comprising a transverse receptacle communicated with the hole, the transverse receptacle comprising an inner longitudinal wall that faces the hole of the head, the handle further comprising a cavity that communicates with the transverse receptacle;
a drive member rotatably mounted in the hole of the head, the drive member including a plurality of teeth formed on an outer periphery thereof;
two pawls mounted in the transverse receptacle in a spaced manner and each including a first side with a plurality of teeth for releasably engaging with the teeth of the drive member and a second side abutting against the inner longitudinal wall of the transverse receptacle;
a switch member including a turn-piece for manual operation, the switch member being rotatably mounted in the cavity of the handle and comprising an actuating portion for selectively moving one of the pawls to a position not engaging with the teeth of the drive member, the switch member further comprising two support portions for selectively supporting a portion of the other pawl that disengages from the inner longitudinal wall of the transverse receptacle, thereby supporting the other pawl that engages with the teeth of the drive member; and
means fo
Kamrath Alan D.
Rider Bennett LLP.
Smith James G.
LandOfFree
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