This invention relates to an automatic hook to be fixed to the free
end of one of the arms of a tractor rear lifting device.
For such lifting devices, hooks are already known for automatically
receiving the ball joint or ball-shaped bush of an agricultural implement, and
for maintaining it automatically locked.
A typical example of such automatic hooks is described in Utility
Model Patent No. 00224647 in the name of the present Applicant.
The hook of said document, to which reference should be made for
greater details, comprises a hook-shaped one-piece flat metal body forming the
coupling seat for the ball joint.
From the upper edge of said one-piece body there upwardly projects
a coplanar ridge presenting two T-shaped enlargements, of which one is close to
said coupling seat for the ball joint and the other is situated at the rear end
of the one-piece body.
The ridge presents a rear slot to which there is hinged an enclosing
shroud which in its turn receives, and carries hinged thereto, the arms of a fork-shaped
element which fits over said ridge, and provides the shutter.
Said fork-shaped element is provided with an engagement seat with
which there engage, by bi-lateral engagement, the two lateral arms of that T-shaped
enlargement which is close to the coupling seat for the ball joint, the engagement
between said engagement seat and said two lateral arms being ensured by an elastically
loaded push rod housed within the one-piece body.
As stated, in such known hooks practically all the members associated
with the shutter, including the shutter itself but excluding the push rod, are
positioned on the one-piece body, behind the coupling seat for the ball joint.
Besides being bulky, said arrangement has the drawback of being constantly
exposed to inopportune impacts against parts of agricultural implements during
their hooking, and against fixed structures during tractor manoeuvres with the
lifting device free.
In this respect, even though the said shroud is intended inter alia
to cover said ridge and said fork-shaped shutter, in the presence of said inopportune
impacts the shroud can warp, and/or its hinging to the ridge can be damaged, with
evident consequences for the operability and safety of the entire system.
Moreover, from the widespread use of said known hook it has emerged
that the internal region of the shroud is not adequately protected against infiltration
of dirt, such as mud, which within a relatively short time results in malfunction,
and hence the need to effect adequate maintenance.
The main object of the present invention is to provide an automatic
engagement hook which is able to overcome the aforesaid problems within the context
of a simple, rational, reliable and robust construction of small overall size.
Said object is attained by virtue of the characteristics indicated
in the claims.
In particular, the hook comprises a hook-shaped one-piece body provided
with a coupling seat for a ball joint, and a shutter arranged to partially obstruct,
and to completely free, said coupling seat by the effect of elastic positioning
means and, respectively, of release means operable from the outside.
According to the invention, the shutter comprises a substantially
cylindrical member which is coplanar with said one-piece body, is positioned tangential
to the rear region of said coupling seat for the ball joint, and is slidingly received
within a housing in the one-piece body in which said elastic means are also received,
and at which said release means terminate.
Said release means preferably comprise a flexible cable passing about
at least one idle pulley, and having one end fixed to the rear end of said cylindrical
member, and its other end coupled to a cap which is removably positioned behind
the body of the hook, and is under the control of a control member.
Preferably said housing comprises two mutually communicating cavities,
of which one is cylindrical and contains said shutter, and the other contains said
release means, and opens into the top rear part of the hook for connecting said
release means to said control member.
The shutter is received in the respective cavity by way of seal means,
said other cavity being closed by a lateral cover and by said cap, and being provided
with at least one grease or oil nipple.
By means of the aforedescribed solution all the objects of the invention
In this respect, the provision of said housing on the one hand reduces
the overall dimensions of the hook, and on the other hand safeguards the integrity
of those members associated with the shutter, seeing that these are protected by
the one-piece body.
In addition the said housing protects against dirt the said means
provided for releasing the shutter, so ensuring the operability of the entire
system with time, aided by the presence of said at least one grease or oil nipple.
The constructional characteristics and merits of the invention will
be apparent from the ensuing detailed description, given with reference to the
figures of the accompanying drawings, which illustrate a preferred embodiment thereof
by way of non-limiting example.
Figure 1 is a side elevation of the invention with parts cut away,
showing the shutter in its locking configuration.
Figure 2 is a part of the section II-II indicated in Figure 1.
Figure 3 is a view entirely similar to that of Figure 1, but without
the cover, and shows a ball joint during its hooking, at the moment in which it
is about to pass beyond the shutter.
Figure 4 is a view entirely similar to the preceding and shows the
hook in the configuration in which the shutter is maintained temporarily released
to enable the ball joint to be extracted.
Figure 5 is a view entirely similar to the preceding and shows the
hook in the configuration in which the shutter is deactivated.
Figure 6 shows on a smaller scale an opposite side view of the hook,
this latter being without the upper cap for closing the housing.
Figure 7 is a view obtained in the direction VII indicated in Figure
Figure 8 is a front view of the cap.
Figure 9 is the section IX-IX indicated in Figure 8.
The said figures, and in particular Figures 1 to 7, show a flat steel
body obtained by casting then machined by machine tools and treated.
The body 1 has the characteristic hook shape, and presents a rear
tapered portion 2 intended to be welded to an arm of a lifting device 3 (indicated
schematically by dashed and dotted lines) of an agricultural tractor, and a front
coupling seat 4 shaped as a portion of a spherical surface.
Said seat 4 is arranged to receive a usual ball joint 5 of a likewise
usual agricultural implement, not shown.
As can be seen, into the region immediately behind said seat 4 there
opens a cylindrical bore 6 of different cross-sections which is centered with respect
to the thickness of the body 1, and is upperly inclined forwards in such a manner
as to intersect a part of the ideal spherical surface defined by the seat 4.
The said bore 6 comprises an upper portion of greater diameter which
slidingly receives a cylindrical member 7, and a lower portion of smaller diameter
which communicates with the lower end of a rear profiled recess 8 of elongate shape
provided in one side of the body 1.
The cylindrical member 7, which forms the shutter for the hook, is
inserted into said bore 6 as a precise free-sliding fit, by way of a dust protection
In the illustrated example the seat for the gasket 9 is formed inside
said bore 6, but it could evidently be provided in the shutter 7.
It is constantly urged forwards by a rear compressed spring 10, and
is guided by a setscrew 11 which is screwed into the body 1, and engages as an
exact fit a longitudinal groove 12 provided in the head of the shutter 7.
The said setscrew 11 also acts as an anti-escape member for the shutter
7 when the coupling seat 4 is free.
In that side facing said seat 4, the free end of the shutter 7 presents
a sunken portion 13 shaped as a portion of spherical surface having its radius
equal to the radius of the seat 4, and an overlying bevel or lead-in 14.
In addition, above the front mouth of the bore 6 the body 1 presents
a sunken portion 15 shaped as a portion of spherical surface having a radius greater
than that of the seat 4, its purpose being to guide the ball joint 5 during its
coupling with the coupling seat 4.
As stated, the lower end of the recess 8 communicates with the bore
6, the said recess 8 opening into that rear region of the body 1 which overlies
said portion 2 by which the hook is connected to the lifting device 3.
It should be noted that the upper mouth of said recess 8 is situated
in an opposite position to the path followed by the ball joint 5 during its coupling
to and release from the seat 4, thus any risk that those members associated with
said upper mouth, and described hereinafter, may interfere with the ball joint
5, or with other elements located within the radius of action of the free hook,
is practically nullified.
As can be seen, along the lateral mouth of the recess 8 there is a
totally extending sunken portion 16, provided to flushly receive a cover 17, which
is fixed to the body 1 by three screws 18.
In detail, the upper end of said cover 17 (see Figure 1) is spaced
from the rear mouth of the recess 8, for the reasons given hereinafter.
On the inner face of said cover 17 and on the base of the recess 8
there are provided support seats for the ends of the shafts of two small idle
pulleys 19 and 20 about which a thin steel cable 21 passes.
At one end the cable 21 is fixed to the rear end of the shutter 7,
and at its other end it is coupled to a cap 22 which is associated with the rear
mouth of the recess 8, and is provided with an operating puller 23.
As can be seen in Figures 8 and 9, said cap 22 is in the form of a
U-piece, of which the crosspiece closes the rear mouth of the recess 8 and the
legs straddle said mouth.
In detail, one of said legs is received flush in that upper part
of the sunken portion 16 not occupied by the cover 17, and the other leg is received
flush in a sunken portion 166 (see Figures 6 and 7) formed in the opposite side
of the body 1.
In addition, said crosspiece of said U-piece presents an outer central
slotted lug 230 for coupling said puller 23, and an inner central appendix 210
for coupling the cable 21.
The appendix 210 is provided with a longitudinal groove 211 for passage
of the cable 21, and with a transverse recess 212 which intercepts said groove
211 to receive the terminal coupling head 221 of the cable 21.
In addition, at the upper ends of the rear sides of said recess 8
and of said sunken portions 16 and 166 there are provided rounded edges 198, whereas
at the upper terminal part of the front side of said recess 8 there is provided
a sharp corner 199.
Finally, with the base of the recess 8 there is associated a grease
nipple 200 (see Figure 6), or alternatively an oil nipple.
The described hook operates as follows.
The ball joint 5 couples automatically to the coupling seat as shown
in Figure 3, with the ball joint 5 causing the shutter 7 to withdraw against the
thrust of the spring 10.
When the ball joint 5 has passed beyond the shutter 7, this latter
automatically assumes the locking configuration shown in Figure 1, with the sunken
portion 13 of the shutter 7 engaging the facing portion of the ball joint 5.
To release the ball joint 5, it is sufficient to withdraw the cap
22 from its seat as shown in Figure 4.
Finally, to deactivate the shutter 7, the previously raised cap 22
is rotated rearwards, about the rounded edges 198, and then released so that its
appendix 210 engages the sharp corner 199 (see Figure 5).
By rotating the cap 22 in the opposite direction the shutter 7 is
reactivated, and in the absence of the ball joint 5 assumes the position defined
by the setscrew 11.
The merits and advantages of the invention are apparent from the
aforegoing and from an examination of the accompanying figures.
The invention is not limited to that illustrated and described, but
covers all technical equivalents of the invention, and their combinations, if implemented
within the context of the following claims.