Tools – Wrench – screwdriver – or driver therefor – Handle clutched to head
Reexamination Certificate
2000-04-03
2001-09-04
Smith, James G. (Department: 3723)
Tools
Wrench, screwdriver, or driver therefor
Handle clutched to head
C081S060000, C081S063000
Reexamination Certificate
active
06282992
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a biasing arrangement for a pawl of a reversible ratchet-type wrench to provide reliable ratcheting. The present invention also relates to an improved head structure for a ratchet-type wrench to lower the manufacture cost.
2. Description of the Related Art
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. 10 and 11
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
′.
SUMMARY OF THE INVENTION
In accordance with a first aspect of the invention, a reversible ratchet-type wrench comprises:
a handle;
a head extended from the handle and including a hole, a web being defined between the handle and the head, a cavity being defined in the web and communicated with the hole, the web further including a compartment having a first end communicated with the cavity and a second end communicated with outside, thereby leaving a bridge in the web;
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;
a pawl mounted in the cavity and including a first side with a plurality of ratchet teeth for releasably engaging with the teeth of the drive member;
a switch member including a turn-piece for manual operation and an actuating plate extended from the turn-piece and rotatably received in the second end of the compartment of the web, the switch member being switchable between two positions for changing ratcheting direction of the drive member; and
a biasing means mounted in the cavity and between the pawl and the actuating plate for biasing the ratchet teeth of the pawl to engage with the teeth of the drive member.
An inner periphery defining the hole of the head includes a first annular groove. The outer periphery of the drive member includes a second annular groove. A C-clip is received in the first annular groove and the second annular groove, thereby rotatably retaining the drive member in the head.
The biasing means includes an elastic element and a peg. The pawl further includes a second side with a recess. The peg has a first end movably received in the recess of the pawl and a second end. The elastic element biases the second end of the peg for exerting a force to the peg toward the pawl, thereby urging the ratchet teeth of the pawl to engage with the teeth of the gear wheel.
In an embodiment of the invention, the actuating plate of the switch member includes a receptacle that faces the cavity. The elastic element includes a first end received in the receptacle and a second end outside the receptacle and configured to be attached to the actuating plate. The second end of the peg is received in the elastic element. The first end of the elastic element is configured to bias the second end of the peg toward the recess of the pawl.
In another embodiment of the invention, the actuating plate of the switch member includes a first receptacle that faces the cavity, the first receptacle having a first end wall. The second end of the peg is received in the first receptacle and includes a second receptacle with a second end wall. Two ends of the elastic element are attached between the first end wall and the second end wall.
The drive member may be a gear wheel including an inner periphery for driving a fastener. Alternatively, the drive member includes a drive column for releasably engaging with a socket. The head includes an end wall with an opening, and the drive member includes a stub rotatably received in the opening.
In accordance with a second aspect of the invention, a reversible ratchet-type wrench comprises:
a handle;
a head extended from the handle and including a hole, a web being defined between the handle and the head, a cavity being defined in the web and communicated with the hole, the web further including a compartment communicated with the cavity;
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;
a pawl mounted in the cavity and including a first side with a plurality of ratchet teeth for releasably engaging with the teeth of the drive member, the pawl further including a second side with a recess;
a switch member including a turn-piece for manual operation and an actuating plate extended from the turn-piece and rotatably received in the compartment of the web, the switch member being switchable between two positions for changing ratcheting direction of the drive member; and
a biasing means mounted in the cavity and between the recess of the pawl and the actuating plate for biasing the ratchet teeth of the pawl to engage with the teeth of the drive member, the biasing means including an elastic element and a peg, the peg having a first end movably received in the recess of the pawl and a second end, the elastic element biasing the second end of the peg for exerting a force to the peg toward the pawl, thereby urging the ratchet teeth of the pawl to engage with the teeth of the gear wheel;
the actuating plate of the switch member including a receptacle that faces the cavity, the elastic element including a first end received in the receptacle and a second end outside the receptacle and configured to be attached to the actuating plate, the second end of the peg being received in the elastic element, the first end of the elastic element being configured to bias the second end of the peg toward the recess of the pawl.
In accordance with a third aspect of the invention, a reversible ratchet-type wrench comprises:
a handle;
a head extended from the handle and including a hole, a web being defined between the handle and the head, a cavity being defined in the web and communicated with the hole, the web further including a compartment communicated with the cavity,
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;
a pawl mounted in the cavity and including a first side with a plurality of ratchet teeth for releasably engaging with the teeth of the drive member, the pawl further including a second side with a recess;
a switch member including a turn-piece for manual operation and an actuating plate extended from the turn-piece and rotatably received in the compartment of the web, the switch member being switchable between two positions for changing ratcheting direction of the drive member; and
a biasing means mounted in the cavity and between the recess o
Kamrath Alan
Rider Bennett Egan & Arundel LLP
Shakeri Hadi
Smith James G.
LandOfFree
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