Work-implement adapter for front loader

An adapter for operatively connecting a work implement such as a bucket or fork to a loader vehicle body. The adapter may be commonly used for connection of various types or sizes of implements. Though easy to use and manufacture, the adapter provides strong, reliable and balanced connection between the vehicle and implement through its pair of side brackets and one center bracket which are rigidly connected with each other via a common support frame and which pivotably connect in substantially straight alignment respectively with a pair of implement lift arms and one implement pivot arm extending from the vehicle body.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a work-implement connecting adapter for a 
front loader for readily and detachably attaching a front-mount work 
implement such as buckets or forks of various capacities depending on the 
necessity, and more particularly to a connecting adapter of the 
above-noted type connecting at a front portion thereof the front-mount 
work implement and connecting at rear portions thereof a pair of right and 
left work-implement lifting arms extending from the vehicle body and a 
work-implement pivot arm disposed at a middle therebetween. 
2. Description of the Prior Art 
A connecting adapter of the above-noted type is known, for example, from a 
Japanese utility model laid open under Showa 63-9350. This adapter is used 
for connecting a bucket as an example of a front-mount work implement and 
a loader vehicle body. More particularly, the bucket projectedly attaches 
on its back face an engaging member for engagement with a tapered engaging 
portion of the adapter which is inserted into the backet from under. The 
bucket further includes at opposed ends thereof a pair of right and left 
bracket members for engagement with lower portions of opposed outer 
peripheral edges of the adapter. On the other hand, the loader vehicle 
body mounts a pair of work-implement lift arms and a work-implement pivot 
arm disposed therebetween, for the engagement with the adapter. Refering 
more particularly to the adapter construction, there is provided a plate 
type frame formed with a curve so as to follow the back face of the 
bucket, the plate frame extending between the entire width between the 
right and left pair of brackets of the front-mount work implement. The 
plate frame forms at its upper end thereof a tapered engaging portion to 
be engaged from under with the engaging member projecting from the bucket 
back face. Further, the plate frame carries a plurality of connecting 
plate members extending vertically and rearwardly from the plate frame and 
for engagement with the pair of work-implement lift arms and the 
work-implement pivot arm, with the plate members acting also for 
reinforcement. Also, the front end of each plate member is formed so as to 
follow the back face of the bucket as is the case with the plate type 
frame. 
Then, if the work implement and the vehicle body are to be connected 
through the above-described construction, the connecting construction 
differs between the case where the adapter is used and the case where the 
adpter is not used (i.e. for using the adapter, there must be provided at 
least a stopper element on the back face of the work implement). 
Accordingly, in order to cope with these cases, two different types of 
work implements are needed. Moreover, it is needless to say that this 
adapter cannot be commonly used for the different types of work 
implements. Further, in this adapter, since the plate type frame curved to 
follow the back face of the work implement is caused to extend over the 
entire width of the work implement, such special formation of the frame 
per ser is troublesome and difficult, and if there occurs a deformation in 
the same through its use, the connecting operation cannot be carried out 
smoothly. Also, the adapter per se is physically large and rather heavy in 
weight. 
In view of the above-described state of the art, the primary object of the 
present invention is to provide an improved work-implement connecting 
adapter which can overcome the above-described various drawbacks of the 
prior device. That is, according to the improved adapter of the invention, 
when the same type of work implement, e.g. bucket is used, there is no 
need for modifying the connecting construction of the implement whether 
the adapter is used or not used for the connection. Further, the adapter 
may be commonly used for different types of work implement such as a 
bucket or a fork and so on. Moreover, the improved adapter is advantageous 
in that the construction is simple and light weight and the adapter can be 
used easily and efficiently for connecting operation. 
SUMMARY OF THE INVENTION 
In order to accomplish the above-described object, according to the present 
invention, the adapter comprises: a pair of right and left side brackets, 
each bracket including a pair of plate members rigidly interconnected via 
a vertical plate frame extending laterally relative to the vehicle body, 
the side brackets pivotably connecting the pair of work-implement lift 
arms and a pair of lifting connected members fixed to the work implement; 
a support frame for fixedly connecting between the inner pair of the plate 
members of the side brackets; and a center connecting bracket disposed at 
an intermediate portion of the support frame and having at a front portion 
thereof an engaging hook portion for pivotably connecting a pivoting 
connected member of the work implement and pivotably connecting the 
work-implement pivot arm at a rear portion thereof. 
With the adapter having the above-described construction, the pair of right 
and left work-implement lift arms and the work-implement pivot arm 
extending from the vehicle body come into connection, from the rear side 
of the adapter body, with the pair of right and left side brackets and the 
center bracket, respectively. Whereas, at the front side of the adapter 
body, the lifting connected members and the pivoting connected member of 
the work implement are pivotably connected with the side brackets and the 
center bracket, respectively. That is to say, the work-implement lift arms 
from the vehicle body and the connecting portions of the work implement 
are connected via the side brackets with substantially straight alignement 
with respect to the transverse direction of the vehicle body. Further, the 
center connecting bracket disposed at the middle portion of the support 
frame pivotably connects at its engaging hook portion at a front side 
thereof the pivoting connected member of the work implement and pivotably 
connects at the rear side thereof the work-implement pivot arm. That is to 
say, with the disclosed construction, the connection between the adapter 
and the work implement is provided only through the above three portions 
which are aligned substantially straight with respect to the transverse 
direction of the vehicle body. For actually carrying out the above 
connecting operations, the vehicle body is advanced towards the work 
implement while maintaining the adapter in such a way as to position the 
center bracket forwardly of the side brackets until the engaging hook 
portion of the adapter comes into hooked engagement with the pivoting 
connected member of the implement. Then, after slightly adjusting, i.e. 
errecting the posture of the adapter for securing the hooked engagement, 
the pivot arm is operated rearwardly for further errecting the adapter 
until the pair of side brackets of the adapter come into overlapped 
engagement with the pair of lifting connected members of the implement 
respectively, whereby the side brackets of the adapter and the connected 
members of the implement are pivotably connected with each other. 
With the above construction, the members such as the work-implement lift 
arms and the work-implement pivot arm required for connections in the 
above construction maintain substantially the same positional 
relationships relative to the transverse direction of the vehicle body. 
Moreover, the connecting constructions of the vehicle body--adapter, and 
the adapter--work implement are provided by the very simple pivotal 
connections using the pins or the like. Then, with the present invention, 
the connecting mechanism may remain unaffected by e.g. the varied 
configurations of the work implements and requires minimum components 
required for the pivotal connections. Accordingly, unlike the prior art, 
the connecting construction may remain the same regardless of the type of 
the front-mount work implement, and also the construction may remain the 
same also whether the adapter is used or not for connecting the work 
implement. Further, on the side of the work implement, the connection is 
effected through the simple arrangement including only the pivoting 
connected member provided at the central position and the lifting 
connected members. Accordingly, this adapter may be commonly used for 
connecting various types of work implement such as a fork or a bucket. 
As for the construction strength, since the work-implement lift arms and 
the work-implement pivot arm are connected via the adapter with the 
lifting connected members and the pivot connected member of the implement 
in substantially straight alignment in the longitudinal direction of the 
vehicle body, there hardly occurs loss or imbalance in the power 
transmission between the vehicle and the implement or distortion of the 
construction. Also, since the construction is formed as a three-point 
connecting structure with the lift members being its center, the 
construction is superior in balance as well. And, because of absence of a 
large plate type member, the adapter is highly resistent against 
deformation yet is light in weight. Moreover, since the right and left 
pair of side brackets are rigidly interconnected via their inner pair of 
side plates through the common support frame, with the side plates of each 
side bracket being rigidly connected through the vertical plate type 
frame. With these features, the construction of the entire adapter is 
superior in strength. 
According to one preferred embodiment of the invention, the adapter further 
comprises: 
a link mechanism for pivotably and detachably connecting the front-mount 
work implement by means of a right and left pair of connecting pins, with 
one connecting pin being pivotably connected to one pivotal end of a pivot 
arm pivotably supported to the support frame whereas the other connecting 
pin being pivotably connected to the other pivotal end of the pivot arm 
via a link, 
wherein a pivotably connected condition is realized if the connecting pins 
slide simultaneously towards the outside to come into engagement with the 
work implement while alternately and selectively a connection-released 
condition is realized if the connecting pins slide simultaneously towards 
the inside to come out of the engagement. 
With the above features, a connecting or disconnecting operation between 
the vehicle and the work implement may be conveniently and selectively 
effected through an operation of the pivot arm which causes the connecting 
pins to simultaneously slide towards either the outside or the inside. 
According to a further embodiment of the invention, the adapter further 
comprising: 
a pivot lock arm for locking the pivot arm at the engaged position and for 
releasing the same therefrom, the locked condition being realized as a 
first stepped portion of the pivot arm comes into engagement with a lock 
engaging portion of the pivot lock arm, and the pivot arm further 
including a second stepped portion which comes into abutment with the lock 
engaging portion thereby limiting movement of the pivot arm towards the 
releasing side exceeding the released position thereof. 
With the above features, the regulations of the two positions, i.e. the 
connected condition and the released condition of the pivot arm, i.e. the 
connecting pins are effected through the engagements of only two members, 
i.e. the pivot arm and the lock arm. Accordingly, the precision in the 
regulations of the respective positions may be improved. Further, a 
switching operation from the released condition to the connected condition 
may be effected very conveniently by operating the pivot arm by means of 
e.g. an operational lever, with no special releasing operation being 
needed. Consequently, the operation may be significantly facilitated and 
the operational safety may be also improved since the pivot type lock arm 
provides a reliably locking effect at the connected condition. 
According to a still further embodiment of the invention, respective pivot 
connecting portions for the lift arms, the pivot arm and the respective 
connecting brackets are recessed forwardly relative to the rear end of the 
support frame 15 the side view, and pivot connecting portions for the 
right and left connected members of the work implement and the respective 
connecting brackets are recessed rearwardly relative to the front end of 
the support frame. 
With the above features, the connections between the lift arms and the work 
implement are positioned at the sides of the reinforcing support frame. 
Also, each side connecting bracket is formed of the pair of plate members 
rigidly interconnected via the vertical plate frame. Accordingly, only the 
plate frame member exists in the fore-and-aft middle portion between the 
pivotal connecting portions with the lift arms and the pivotal connecting 
portions with the work implement, whereby it becomes possible to reduce 
the fore-and-aft interdistances between the respective connections. In the 
case of the center connecting bracket, its forward and rearward pivot 
connection portions may be disposed close to each other as there exist no 
elements therebetween. Then, similarly to the side connecting brackets, if 
the connecting portions are recessed from the front and rear ends of the 
support frame respectively, the fore-and-aft distance may be reduced. 
Consequently, the driving and operating feels of the front-mount work 
implement do not significantly change from those of the case of direct 
connection, and the operational efficiency has been improved.

DESCRIPTIONS OF THE PREFERRED EMBODIMENTS 
Preferred embodiments of the present invention will be particularly 
described hereinafter with reference to the accompanying drawings. 
FIG. 1 shows a work vehicle equipped with a workimplement connecting 
adapter A related to the present invention. This work vehicle includes a 
front body 2 having a front loader implement 1 and a rear body 5 having a 
driver's cabin 3, an engine and so on. The front body and the rear body 
are interconnected as being pivotably relative to each other about a 
vertical axis X by an extension or contraction of a hydraulic cylinder 7 
operated by a steering wheel 6. 
The front loader 1 includes a pair of right and left work-implement lift 
arms 9, 9 extending forwardly from the front body 2 and lifted up and down 
by a hydraulic cylinder 8, a work-implement pivot arm 11 disposed at the 
middle between the right and left arms and pivotable about a horizontal 
axis by means of a hydraulic cylinder 10, with the arms 9, 9 and the arm 
11 being connected to a rear portion of the adapter A, and a digging 
bucket 12 detachably attached to a front portion of the adapter A. The 
bucket 12 may be directly connected to the respective arms 9, 9 and 11 
without the adapter A. 
Next, refering to FIG. 2, the adapter A includes a pair of right and left 
side connecting brackets 14 and 14 for pivotably connecting the lift arms 
9, 9 and a pair of lifting connected members 13, 13 fixed to the bucket 
12, with the brackets 14, 14 being fixedly interconnected via a round pipe 
type support frame 15. Each side connecting bracket 14, 14 includes a pair 
of right and left plate members 16, 16 aligned in the fore and aft 
direction and fixedly interconnected via a laterally extending vertical 
plate frame 17, and the inner plate members 16, 16 of the brackets are 
rigidly connected to each other via the support frame 15. At a rear side 
of the vertical plate frame 17, the lift arm 9 is inserted and pivotably 
connected at a position between the plate members 16, 16 by means of a pin 
18. 
Further, at the middle point of the support frame 15 in the right and left 
direction, there is fixedly welded a center connecting bracket 20 for 
pivotably connecting an engaging pin 19 as one example of a connected 
member for pivoting the pivot arm 11 and the bucket 12. A leading end of 
the pivot arm 11 is inserted and pivotably connected thereat by a pin 21 
between a pair of plate members 20a and 20a projecting rearwardly of the 
center connecting bracket 20. The engaging pin 19 is pivotably engaged at 
a stopper hook portion 22 formed at a forward portion of the bracket 20. 
On the front side of the vertical plate frames 17, 17 of the side 
connecting brackets 14, 14, there are formed connecting portions 24 and 24 
recessed in between the connected members 13 and 13 while overlapping each 
other as viewed sidewise and to be inserted therethrough by the connecting 
pins 23 and 23. The connecting pins 23 and 23 are separatively connected 
to each other via a link mechanism 26, such that with a pivotal operation 
of the single operational lever 25, the connecting pins 23 and 23 slide 
simultaneously in the opposite directions to selectively provide a 
pivotably-connected condition and a disconnected condition between the 
adapter A and the bucket 12. For permiting a visual confirmation of the 
completion of connection of the connecting pins 23, 23, the outer side 
plate members 16 and 16 of the side connecting brackets 14, 14 are so 
formed as to allow visual inspection of the connecting portions 24 and 24 
from the outside of the vehicle. 
With the above-described construction, the connecting operation of the 
bucket 12 may be readily carried out. That is, for connecting the bucket 
12, as illustrated in FIG. 3, with maintaining the center connecting 
bracket 20 positioned forwardly of the side connecting brackets 14 and 14, 
the vehicle body is driven forwardly to bring the engaging pin 19 of the 
bucket 12 into a hooked engagement with the stopper hook portion 22. Then, 
the driving arm 11 is driven rearwardly to insert the lifting right and 
left connecting portions 24 and 24 into the connected members 13 and 13; 
and in this condition, the operational lever 25 is operated to connect the 
pins 23 and 23, whereby the connecting operation is completed as 
illustrated in FIG. 4. 
Next, as shown in FIG. 5, respective pivot connecting portions R1 and R2 
for the lift arms 9. 9, the pivot arm 11 and the respective connecting 
brackets 14 and 20 are recessed forwardly relative to the rear end of the 
support frame 15 in the side view. Also, the pivot connecting portions R3 
and R4 for the right and left connected members 13 and 13 of the bucket 12 
and the respective connecting brackets 14 and 20 are recessed rearwardly 
relative to the front end of the support frame 15. Moreover, the pivot 
connecting portions R1, R3 and R2, R4 are positioned on the same 
altitudes, respectively. 
With this arrangement, compared with the case where the bucket 12 is 
directly connected to the respective arms 9, 9 and 11 without using the 
adapter A, it becomes possible to minimize a length L of the forward 
displacement of the bucket 12, i.e. the offset amount. Further, since the 
vertical position of the bucket 12 does not change, there occurs no 
significant variation in the driving and operating feels. Next, referring 
to FIGS. 6, 7 and 8, a pivot arm 28, which is oriented in the fore and aft 
direction, is fitted to a support member 27 having a hook shape in plane 
view and fixedly welded on the support frame 15. On the pivot shaft 28, 
there is pivotably mounted a pivot arm 29. This pivot arm 29 pivotably 
connects at one pivotal end thereof the left connecting pin 23 through a 
slot 30a and an engaging pin 39 projecting from an inner side face of the 
left connecting pin 23. Further, the other pivotal end of the pivot arm 29 
is pivotably connected to the right connecting pin 23 via a link 31 having 
a letter `L`-shaped configuration in the front view. That is, the link 31 
is pivotably supported on the pin 38 continuously formed from the pivot 
arm 29. A lower pivotal end of a middle pivot link 33 pivotably supported 
by a support member 32 having a hook-shaped configuration in the plane 
view and welded to the support frame 15 is pivotably connected to the 
right connecting pin 23 via a slot 34a and an engaging pin 40. Further, an 
intermediate portion of the middle pivot link 33 and the right end of the 
`L`-shaped link 31 are pivotably connected to each other. On the other 
hand, the operational lever 25 is integrally fixed to and operatively 
connected with the pivot arm 29. 
In operation, as the operational lever 25 is pivoted, the connecting pins 
23 and 23 simultaneously slide towrds the outside to come into engagement 
with the connecting portions 24, 24 of the side connecting brackets 14 and 
14 and also with the connected members 13, 13 of the bucket 12, thereby 
pivotably connecting between the adapter A and the bucket 12. Alternately, 
the connecting pins slide towards the inside to release the operative 
connection between the same. 
Further, as shown also in FIG. 6, there is provided a pivot lock arm 35 for 
locking the pivot arm 29 at the operatively connected condition and for 
releasing the same from this condition. More particularly, on a front 
outer face of the support frame 15, there is welded a support member 36 
acting as a pivot point element. And, the lock arm 35 is pivotably 
supported at a pivot support portion 36a of the support member 36. This 
lock arm 35 is integrally formed letter `L`-shaped in the side view with 
its pivotal end being bent upwards. On the other hand, at an intermediate 
position of the side face of the pivot arm 29, there is defined a first 
stepped portion 29a, whereby in the operatively connected condition this 
first stepped portion 29a of the pivot arm 29 comes into engagement with a 
horizontal portion 35a acting as a lock engaging portion of the pivot lock 
arm 35 and locked thereat. For releasing the lock arm 35, its pivotal end 
is manually swung to the left to come out of the engagement with the first 
stepped portion 29a. Further, the lock arm 35 is urged towards the locking 
direction by means of a spring 37 disposed between the arm 35 and the 
support member 27, whereby the lock arm 35 may reliably provide the 
locking effect. 
Upwardly of the first stepped portion 29a of the pivot arm 29, there is 
formed a second stepped portion 29b acting as a contact engaging portion. 
As this second stepped portion 29b comes into fixed engagement with the 
horizontal portion 35a of the pivot lock arm 35, it becomes possible, in 
the connection-released condition, to limit movement of the pivot arm 29, 
i.e. the connecting pins 23, 23 exceeding the connection-released 
condition. 
In this way, while inadvertent disengagement of the connecting pins 23, 23 
is reliably prevented, the operational lever 25 may be operated directly 
when the operative connection is needed, whereby the operability has been 
improved. Moreover, since the regulations of the two positions are 
effected only through the engagement between the lock arm 35 and the pivot 
arm 29, the positioning operations may be effected with higher precision. 
FIGS. 9 and 10 illustrate an alternate embodiment of the above 
construction. In this embodiment construction, one pivotal end of the 
pivot arm 29 is pivotably connected with the left connecting pin 23 
through an auxiliary link 30b, and the other pivotal end of the arm 29 is 
pivotably connected with the right connecting pin 23 through a link 31 
having a letter `L`-shaped configuration in the front view. More 
particularly, the link 31 is pivotably supported on a pin 38 extending 
continuously from the pivot arm 29. The lower pivotal end of the middle 
pivot link 33 pivotably supported by the support member 32 having a 
hook-shaped configuration in the plane view and welded to the support 
frame 15 is pivotably connected to the right connecting pin 23 via an 
auxiliary link 34b. Further, the intermediate portion of the middle pivot 
link 33 and the right end of the `L`-shaped link 31 are pivotably 
connected to each other. On the other hand, the operational lever 25 is 
integrally fixed to and operatively connected with the pivot arm 29. 
In operation, if the operational lever 25 is operated for the releasing 
action, the `L`-shaped link 31 comes into contact with the support member 
36, thereby limiting further movement of the lever 25 towards the 
releasing direction. In this released condition, the pivot arm 29 has its 
position maintained by the contact urging force applied by the 
spring-urged lock arm 35. 
With the above construction, the locking mechanism for locking the 
connected condition acts also as a movement limiting member for limiting 
the movement of the arm towards the releasing direction, whereby the 
construction has been simplified. 
Next, a positioning mechanism for the adapter and the work implement will 
be described with reference to FIGS. 11 through 15. As shown, the left 
side connecting bracket 14 and the left lifting connected member 13 
respectively include at a left side portion thereof target guide members 
50a and 50b for aligning the fore and aft positions of the adapter A and 
the bucket 12. These guide members 50a and 50b, as illustrated in FIG. 15, 
have respective leading ends thereof opposed in parallel with each other 
in the right and left direction when the fore and aft positions of the 
stopper hook portion 22 and the engaging pin 19 are aligned to each other. 
With the above-described target guide members 50a and 50b, the positioning 
operations with a forward travelling of the vehicle body as illustrated in 
FIGS. 12 and 14 may be carried out very easily. 
Alternately, as shown in FIGS. 16 and 17, the guide members 50a and 50b may 
be formed of horizontally oriented bar members, such that in the positon 
aligned condition the guide members are positioned adjacent each other in 
the fore and aft direction and overlapped each other as viewed from the 
driver of the vehicle. 
Also conceivably, the guide members 50a and 50b may be disposed either at 
the right or left side of the vehicle body. 
Incidentally, although reference marks and numerals are provided in the 
appended claims of the patent application for the purpose of facilitating 
reference to the accompanying drawings, it is to be understood that these 
are not to limit the scope of the invention to those constructions 
illustrated in the drawings.