The monkey wrenches consist in a set built up of a fixed clamp that
forms a body of one only piece with the tool handle and a mobile jaw that is moveable
in approach and separation regarding the mentioned fixed clamp, this mobile jaw
is provided with a toothed rack, with which it engages a drive nut that is mounted
in such a way it can turn freely on a shaft.
Conventionally, the mentioned drive nut is disposed on a rigid metallic
shaft, incorporating, in one end of the nut housing, a pusher spring, so as to
avoid this way the axial looseness of the nut. The movable jaw remains nevertheless
with a certain looseness in the gear with regard to the nut, which causes undesirable
noises when moving the key.
To avoid that problem of the looseness of the mobile jaw, a solution
is known. It consists in preparing the drive nut divided into two axially consecutive
parts, with a reduction of the separation between the fillet carvings of the gear
thread with the mobile jaw, in the area of the mentioned nut division, with which,
by virtue of the pushing of the spring, which eliminates the axial looseness the
contact of the lateral parts of the fillets of the threading of one of the two
parts of the nut components is produced, against the lateral faces of the rack
teeth of the mobile jaw, avoiding with it the looseness of the mentioned mobile
jaw. The execution and assembly of this solution is however complicated, being
it moreover expensive to carry out the nut in two independent pieces.
A solution is also known to allow the separation of the drive nut
regarding the gear with the mobile jaw, so as to allow the quick movement of the
mentioned mobile jaw; in the way it is indicated in the US patents 1.402.686 and
2.724.301. With this same concept, the Chinese patent 92242425 offers a solution
according to which a helical spring is disposed as the shaft of the worm. It is
compressed between two extreme balls that support against some inclined planes,
with which, when pulling at the worm in the sense of their separation with respect
to the rack of the mobile jaw, the sliding of the extreme balls of the shaft along
the inclined supporting planes, makes that the spring that forms the shaft is
compressed axially at the same time as it moves together with the worm in the separation
sense respect to the rack of the mobile jaw, allowing this way the liberation
of the mobile jaw with regard to the worm.
French Patent 2.126.534 discloses a solution in which the worm is
forced by a flexible element to be always in engagement with the rack of the mobile
jaw; this flexible element allowing that the worm may be pushed out of engagement
with the rack (3).
In accordance with the present invention, there is provided a monkey
wrench as defined in the appendent independent claim 1.
The present invention provides a new assembly solution for the drive
worm, to be able to join the two previously mentioned functions, eliminating the
looseness and with the possibility to liberate the mobile jaw, obtaining some
more advantageous constructive and functional characteristics than with the solutions
up to now developed.
The new solution consists in preparing the drive worm on a flexible
shaft of elastomer material, according to an assembly disposition so that this
shaft, because of its flexion, pushes the mentioned drive worm towards the mobile
This way, a radial pressure of the drive worm is reached, against
the mobile jaw, which, in combination with the inclination of the flanks of the
teeth and the gear threads between both pieces, cancels the slackness of the gear,
reaching this way a certain fixation of the mobile jaw, so that undesirable noises
do not take place.
The own flexibility of the shaft allows, on the other hand that the
drive worm can be moved in a forced way in the opposite sense of its pressure against
the mobile jaw, thanks to the elastic deformation of the shaft.
This allows to liberate the mobile jaw from its connection with the
drive nut, so as to leave this mobile jaw free from a quick displacement in the
approaching or separating sense regarding the fixed clamp, with which the adjusting
of the wished opening of the key is easier and quicker.
In combination with that displacement possibility of the drive nut,
until the release of the gear between the nut and the mobile jaw is reached, a
realization of the teeth and of the gear thread is foreseen with a lateral one
according to some inclined planes, with an inclination orientated in the sense
of approach of the mobile jaw towards the fixed clamp.
With it such a disposition is obtained that, by means of a simple
push of the mobile jaw towards the fixed clamp, an elastic jump of the rack teeth
of the mentioned mobile jaw takes place regarding the threads of the drive nut,
due to the displacement in the separation sense to which the mentioned nut is subjected
when sliding the inclined lateral plane of its fillets on the inclined lateral
plane of the rack teeth of the mobile jaw, reaching this way a ratchet effect that
allows the quick closing of the key by means of only the push of the mobile jaw
towards the fixed clamp.
This particularity supposes a great advantage for the handling of
the key, since it allows its quick closing for its approach to the measure of the
object on which it has to act, being able to carry out that closing in an easy
way, even in uncomfortable and difficult positions, since it is only necessary
to push the mobile jaw towards the fixed clamp, which is executable by the user
with a single hand, allowing this way the performance of the wrench in a much easier
way in places where the access with both hands at the same time is difficult
or impossible. It is worth pointing out in this respect that the approaching movement
of the jaws is the one which particularly interests in a quick way when using
the wrench, since the wrench should be prepared with a sufficiently open width,
to insert it on the actuation element, on which it is adjusted once inserted;
while to retreat the wrench, once carried out the performance, only a slight separation
of the jaws is necessary to be able to retire the wrench without difficulty.
The liberation of the mobile jaw regarding the gear with the drive
nut, by the movement of the latter, allows that this mobile jaw can even be extracted
out of its housing assembly in the wrench, in combination with which a realization
with the provided mobile jaw of a plane front in one of its parts and with incorporation
of a toothed piece in the opposed front, in such a way that, by means of the extraction
of the mentioned mobile jaw out of its assembly housing, the position of the same
can be inverted regarding the fixed clamp, allowing this way the adaptation of
the wrench to act on polygonal elements and also to act on cylindrical elements.
The flexible elastomer shaft of the drive worm is built up of a compact
cylindrical body of a diameter in correspondence with the assembly housing of the
wrench, being the fixed disposition of the mentioned shaft foreseen in a preferable
way by means of the gluing of its ends in the assembly housing; although also,
without departing from the invention, the mentioned shaft body can incorporate
a threaded head in a solidary way joined in one end, for the fastening by means
of a threaded assembly in the corresponding housing.
The shaft body can moreover incorporate, in an optional way, inside
the elastomer material, reinforcements with the help of bars or metallic plates,
by means of which at the same time the flexion strength of the mentioned shaft
can be reinforced.
In view of all this, the mentioned monkey wrench object of the present
invention indeed has some very advantageous characteristics as compared to the
conventional monkey wrenches.
Figure 1 represents a monkey wrench in agreement with the invention.
Figure 1a is an enlarged partial view corresponding to the end where
the head of the wrench is situated.
Figure 2 is a corresponding profile of the same extreme part of the
wrench represented in the previous figure.
Figure 3 is a section lateral view and at greater scale of the wrench
Figure 4 is a detail in an enlarged section of the drive worm assembly
of the wrench in its disposition on the corresponding flexible shaft, according
to a non limitative example of a practical realization.
Figure 4a is a detail as the previous one, with the flexible shaft
of the nut provided with bushings incorporated at the ends.
Figure 5 is a similar detail of the assembly of the drive nut of
the wrench in its disposition on the corresponding flexible shaft, according to
another realization example.
Figure 6 is a traverse section of the flexible shaft according to
the indication VI - VI pointed out in the detail of the previous figure, having
represented some radial arrows around A, B, C, and D which indicate the flexion
and rigidity directions of the mentioned shaft in this realization.
Figure 7 is a detail in an outline that shows the radial deviation
in the assembly between the half part of the flexible shaft which incorporates
the drive nut and the ends of the mentioned shaft.
Figure 8 is an outline that represents the sliding gear towards one
side between the rack of the mobile jaw and the drive nut.
Figure 9 is a representation as the one of the previous outline,
being indicated in "dot and dash line" the position of the drive worm and of the
mobile jaw in the jump of the gear between both when the mobile jaw is pushed.
Figure 10 is a sectional lateral view of the wrench head, according
to a realization of a reversible assembly of the mobile jaw.
Figure 10a is a representation to a smaller scale of the wrench head
in the realization of the previous figure, with the drive worm disengaged regarding
the mobile jaw.
Figure 10b is a representation as the previous one, with the mobile
jaw inverted in its position regarding the fixed clamp.
The monkey wrench according to the invention includes a fixed clamp
(1) forming an only piece with the body of the handle and a mobile jaw (2), moveable
in the approach and separation senses with regard to the mentioned fixed clamp
(1), possessing the mentioned mobile jaw (2) a toothed rack (3), with which a
drive worm (4) is connected, prepared in free turn on a shaft (5) , so that the
turning operation of the mentioned nut (4) causes the displacement of the mobile
In accordance with the invention, the drive worm (4) is disposed
incorporated on a shaft (5) of elastomer material, such as rubber or similar, so
that the mentioned shaft (5) is flexible, being foreseen its disposition according
to an assembly with tendency to push the worm (4) towards the mobile jaw (2).
That pushing effect of the worm (4) towards the mobile jaw (2) is
reached by the flexibility of the shaft (5) itself and its assembly disposition,
since in the assembly the mentioned shaft (5) is disposed in such a way that its
ends are included in a housing (6) whose longitudinal shaft (11) is located with
regard to the mobile jaw (2) at a distance somewhat smaller than the own central
shaft (12) of the worm (4), in the way it is represented in figure 7, with which
the shaft (5) remains exercising, a push of the mentioned worm (4) towards the
mobile jaw (2), because of its flexible recovery effect.
This way, the worm (4) remains pressed against the mobile jaw (2),
with which the looseness of the gear between both pieces is cancelled, being this
way the mobile jaw (2) with a fixation that avoids its free mobility in the clearance,
with which a greater precision is obtained as well as a softness in the displacement
of the mentioned mobile jaw (2), avoiding the noises because of the looseness of
In a conventional way, the worm (4) is also pushed axially by a spring
(7), as it can be observed in figures 4 and 5, with which the clearance in this
axial sense is also eliminated, also avoiding this way that noises take place
because of the looseness in that axial sense.
The flexible shaft (5) is built up of a compact cylindrical body,
with a diameter in correspondence with the assembly housing (6) in the wrench,
determining the mentioned cylindrical body with a very refined external surface,
so that in the disposition of the worm assembly (4) the latter can slide on the
mentioned shaft (5), allowing a gentle operation of the necessary rotation for
the displacement of the mobile jaw (2).
The assembly of the mentioned shaft (5) is established with a fixation
of its ends in the corresponding housing (6), for which, according to a possible
practical realization, it is foreseen that the extreme parts of the mentioned shaft
(5) remain fixed in the housing (6) by means of its gluing.
This gluing fixation can be carried out directly between the ends
of the shaft body (5) and the housing wall (6), in the way it is represented in
figure 4, in which case it is necessary to use glue that is compatible with the
elastomer material that builds up the mentioned shaft body (5).
According to a possible realization variant, at the ends of the shaft
(5), some bushings (8) can be incorporated, in the way it is represented in figure
4a, the mentioned bushings (8) can be of any rigid material that allows the use
of all kind of glues, for example for metallic material; to establish the shaft
fixation (5) in such a case, by means of the gluing of the mentioned bushings
(8) on the wall of the housing (6).
In such a realization the bushings (8) are incorporated preferably
by means of their integration in the moulded production of the synthetic body of
the shaft (5), being foreseen that the mentioned bushings (8) are provided with
holes and/or grooves so that the elastomer material of the moulded body is inserted
in them, being this way an only monoblock body. The mentioned bushings (8) could
however be incorporated on the ends of the shaft (5), by means of any other solidarization
technique, without altering the essentiality of the invention.
According to another possible realization, a threaded head (13) can
be incorporated to the synthetic body of the shaft (5) which is solidarily united
at an end, allowing this way the attachment of this shaft (5) by means of an assembly
threaded into the housing (6), in the way it is represented in figure 5.
On the other hand the worm (4) is foreseen with some widenings at
the end of its axial passage hole of the shaft (5), with which the mentioned ends
of the worm (4) remain with a clearance regarding the mentioned shaft (5), allowing
a certain radial flexion of the shaft body (5) in those areas in the assembly disposition.
The mentioned radial flexion possibility of the shaft (5), allows
the forced displacement of the worm (4) in the sense of its separation regarding
the rack (3) of the mobile jaw (2), being able to remain this worm (4) completely
disjointed from the engagement with the mentioned rack (3) of the mobile jaw (2),
being then the mentioned mobile jaw (2) free of displacement, in such a way that
it can be moved in a quick way and without the need of the revolvable drive worm
(4), for the approach or separation regarding the fixed clamp (1).
To facilitate the manipulation of the worm (4) in any event, both
in its revolvable operation for the slow mobility of the mobile jaw (2), and in
the radial displacement for the quick mobility of this mobile jaw (2), the lower
part of the housing (9) defines a bevel (10) in its external lateral faces. This
allows a free sliding of the user's fingers in the operation, facilitating this
way the manipulation.
In combination with the possibility of a radial displacement of the
worm (4) by the elastic flexion of the shaft (5), a realization is foreseen so
that the helical ribs of the worm (4) and the corresponding rack teeth (3) of
the mobile jaw (2) determine some reciprocal inclined planes (21), in one of the
sides, as it can be observed in figure 3.
With it, the support between the indicated helical ribs of the worm
(4) and the mentioned teeth of the mobile jaw (2) results in a sliding effect in
the sense of approach of this mobile jaws (2) towards the fixed clamp (1), which
allows that, by means of the pushing of the mobile jaw (2) towards the fixed clamp
(1), the closing of the wrench can be carried out immediately, due to the sliding
jump of the teeth of the mobile jaw (2) on the helical ribs of the worm (4) in
combination with the radial displacement of the worm (4), by the pushing that
this one suffers in consequence in the radial sense, giving rise to a ratchet effect.
The liberation of the mobile jaw (2) by the forced radial displacement
of the worm (4), allows that the mentioned mobile jaw (2) can even be extracted
out of its assembly housing in the wrench.
In combination with it, a realization of the mobile jaw (2) is foreseen
provided with a flat front (15) in one of its parts and with incorporation of a
toothed piece (16) in the opposed part, with which, by means of the extraction
of the mentioned mobile jaw (2) of its assembly housing, its position can be inverted,
in the way it is represented in figures 10a and 10b, allowing this way the adaptation
of the wrench to act on polygonal elements, by means of the disposition with the
flat front (15) opposed to the fixed jaw (1), or to act on cylindrical elements,
by means of the disposition with the piece (16) facedto the fixed jaw (1), in which
a corresponding toothed front (17) is foreseen to such an effect.
In a particular way, the toothed piece (16) is foreseen according
to a sliding assembly, acted by a spring (18) towards a fixed position, with the
purpose of facilitating the operative disposition of the wrench on the cylindrical
elements of application with the necessary adjustment so that the performance of
the wrench is effective.
The flexible shaft (5) of assembly of the worm (4) can be of any
elastomer material that allows an appropriate elasticity and which at the same
time has the necessary rigidity to support the worm (4) in its operative disposition,
having carried out satisfactory tests, to such an effect and in connection with
a disposition of the mentioned shaft (5) directly glued with regard to the assembly
housing (6), with a realization of the mentioned shaft (5) with the help of natural
elastomer materials, such as rubber or synthetic material as for example acryl-nitrile-butadiene
"NBR", or chloroprene polymers "CR"; but in general, practically, the realization
of the mentioned shaft (5) can be carried out by any kind of elastomers, such as
silicone, "VMQ", fluoric silicone "FUMQ", polyacrylates "ACM", or those of the
type "HNBR", "FKM", "EPDM", etc...
The determination of the shaft (5) by a cylindrical body of an only
piece, allows its obtaining by simple cutting starting from a continuous body;
but in a same way the acquisition can be by moulding, being able to adapt the
conformation that is required in each case, even with different sections as it
suits to the application disposition in the wrench.
This does not suppose an alteration of the essentiality of the object,
the mentioned cylindrical body of the shaft (5) can be supplemented with false
accessory elements, such as the extreme bushings (8) themselves for the gluing
into the housing (6), or other pieces of a similar finish, as well as a central
bushing (19) to facilitate the revolvable sliding of the nut (4), or flexible
elements, such as bars or strips (20) integrated inside the elastomer material,
to reinforce the resistance and the strength of the flexibility of the elastomer
material in the way it is represented in figure 5.
In the case of inclusion of a flat strip (20) in the inside, the
flexion of the shaft (5) is guided, whenever, considering the directions indicated
in figure 6, the flat strip (20) can only bend according to the direction A -
B, determining on the contrary undeformable rigidity in the direction C - D. This
makes that the flexion of the shaft (5) can be established only to act in the
sense in which the mobile jaw (2) is formed, being on the contrary rigid in the
perpendicular sense, which avoids that an undue flexion of this shaft (5) can
take place in the sense C - D by the pushing exercised when the worm (4) is being
operated by the user.