U.S. patent number 3,568,869 [Application Number 04/790,050] was granted by the patent office on 1971-03-09 for antirollback mechanism.
This patent grant is currently assigned to J. I. Case Company. Invention is credited to Gary L. Beiley, Gary A. Dickman.
United States Patent |
3,568,869 |
Beiley , et al. |
March 9, 1971 |
ANTIROLLBACK MECHANISM
Abstract
A loader unit mounted on a tractor and including pivotally
mounted lift arms on which there is pivotally supported a bucket
controlled by a hydraulic circuit including a bucket control
cylinder. The loader unit includes an antirollback mechanism
incorporating a control member and a control link. The control
member is moved relative to the link in response to movement of the
bucket control operating lever; and the control link is movable
relative to the control member by raising and lowering of the lift
arms and pivoting of the bucket relative to the lift arms so that
the link engages the control member to prevent rollback of the
bucket when the bucket and the arms are in position to permit
rearward dumping of the bucket.
Inventors: |
Beiley; Gary L. (Terre Haute,
IN), Dickman; Gary A. (Milwaukee, WI) |
Assignee: |
J. I. Case Company (Racine,
WI)
|
Family
ID: |
25149494 |
Appl.
No.: |
04/790,050 |
Filed: |
January 9, 1969 |
Current U.S.
Class: |
414/701;
414/713 |
Current CPC
Class: |
E02F
3/34 (20130101) |
Current International
Class: |
E02F
3/28 (20060101); E02F 3/34 (20060101); E02f
003/30 () |
Field of
Search: |
;214/764,763,762,775,776,773,771 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Makay; Albert J.
Claims
We claim:
1. A material-handling device comprising in combination a support
structure, lift arm means pivotally connected to said support
structure, a bucket, means for pivotally supporting said bucket on
said lift arm means, means for raising and lowering said lift arm
means, a bucket operating system including bucket control linkage
connected between said bucket and said lift arm means, a hydraulic
circuit comprised of a bucket control cylinder connected between
said bucket control linkage and said lift arm means and a bucket
control valve, a bucket operating lever, a bucket operating linkage
connecting said operating lever, to said bucket control valve for
operating said valve and cylinder in response to movement of said
bucket operating lever, whereby movement of said bucket operating
lever into a first position rolls said bucket back relative to said
lift arm means and movement of said bucket operating lever into a
second position rolls said bucket forward relative to said lift arm
means, a bucket antirollback control member having an arcuate
control surface, means for pivotally mounting said bucket
antirollback control member on said support structure, a bucket
antirollback control rod, means for pivotally connecting one end of
said bucket antirollback control rod to said bucket control
linkage, a sleeve slideably supporting the other end of said bucket
antirollback control rod, means for pivotally mounting said sleeve
to said support structure to allow pivoting movement of said other
end of said bucket antirollback control rod through the arcuate
path defined by the surface of said antirollback control member
during raising and lowering of said lift arm means and to allow
sliding movement of said bucket antirollback control rod towards
said bucket antirollback control member when said lift arm means is
raised and said bucket is rolled back and away from said bucket
antirollback control member when said lift arm means is lowered and
said bucket is rolled forward, and linkage means connecting said
bucket antirollback control member to said bucket operating linkage
for pivoting said bucket antirollback control member towards said
other end of said bucket antirollback control rod in response to
movement of said bucket operating lever into its first position and
for pivoting said bucket antirollback control member away from said
other end in response to movement of said bucket operating lever
into its second position, whereby said other end of said bucket
antirollback control rod engages the arcuate control surface of
said bucket antirollback control member when said bucket is level
and said lift arm means is raised to prevent movement of said
bucket operating lever into its first position and rollback of said
bucket past its level position.
2. A material-handling device in accordance with claim 1 in which
said sleeve terminates short of both ends of said bucket
antirollback control rod and said sleeve mounting means includes
means for pivotally mounting said sleeve beyond the end thereof
whereby the pivoting movement of said bucket antirollback control
rod is about a point beyond the end of said sleeve and short of the
other end of said bucket antirollback control rod.
3. A material-handling device comprising in combination a support
structure, lift arm means, a bucket, means for pivotally supporting
said bucket on one end of the said lift arm means, means for
connecting said lift arm means to said support structure, means for
operating said bucket to roll said bucket forward and back relative
to said lift arm means, a control member, a bucket antirollback
link, means for supporting said link between said operating means
and said control member for sliding movement of said link towards
said control member in response to rollback of said bucket relative
to said lift arm means and for sliding movement away from said
control member in response to rolling forward of said bucket
relative to said lift arm means, said link having a free end facing
said control member, means for connecting said control member to
said bucket operating means for moving said control member toward
said link in response to rollback of said bucket and for moving
said control member away from said link in response to rolling
forward of bucket relative to said lift arm means, said control
member having a surface positioned to be engaged by the free end of
said antirollback link when said bucket is at its level position
and said operating means is actuated to roll said bucket back
relative to said lift arm means, whereby additional movement of
said bucket operating means to roll back the bucket past its level
position is prevented.
4. A material-handling device in accordance with claim 3 in which
said bucket operating means includes an operating lever, movable
into a first position to roll back said bucket relative to said
lift arm means, in which said means connecting said control member
to said bucket operating means includes a mechanical linkage
interconnecting said control member and said operating lever for
movement of said control member towards said link in response to
movement of said operating lever into its first position and for
movement of said operating lever out of its first position in
response to movement of said control member away from said link,
whereby engagement of said link with said control member causes
movement thereof away from said link to prevent operation of said
lever to roll back said bucket past its level position.
5. A material-handling device in accordance with claim 3 in which
said control member includes an arcuate control surface, and in
which said link supporting means includes means for allowing
pivotal movement of said one end of said link along said arcuate
path.
6. A material-handling device in accordance with claim 3 in which
said bucket operating means includes bucket control linkage
interconnecting said bucket and said lift arm means, and in which
the other end of said link is pivotably connected to said bucket
linkage.
7. A bucket antirollback mechanism for a material-handling device
comprising in combination a support structure, lift arm means,
means for pivotally supporting one end of said lift arm means on
said support structure, means for raising and lowering said lift
arm means, a bucket, means for pivotally supporting said bucket on
the other end of said lift arm means, bucket control linkage
connected between said bucket and said lift arm means, an operating
lever, means connecting said operating lever to said bucket control
linkage for operating said linkage to roll said bucket back
relative to said lift arm means when said operating lever is in a
first position and for rolling said bucket forward relative to said
lift arm means when said operating lever is in a second position,
an antirollback control member, an antirollback control link, means
for connecting one end of said link to said bucket control linkage
and for supporting the other end of said link for pivotable and
sliding movement of said link towards said control member during
rollback of said bucket and away from said control member during
forward roll of said bucket, said other end of said link being free
and facing said control member, and means for connecting said
control member to said operating lever for moving said control
member towards said control link during movement of said operating
lever into its first position and for moving said control member
away from said control link during movement of said operating lever
into its second position, said control member having a surface
positioned to be engaged by the free end of said control link when
said operating lever is in said first position and said raising
means has raised said lift arm means beyond a predetermined angle,
said control member moving away from said link in response to the
free end of said link engaging said control member when said
operating lever is in its first position and said bucket is rolled
back to its level position to move said operating lever out of said
first position thereby preventing rollback of said bucket past its
level position.
8. A material-handling device comprising in combination lift arm
means, a bucket pivotally supported on said lift arm means, means
for raising and lowering said lift arm means, means for operating
said bucket to roll said bucket forward and back relative to said
lift arm means, a control member, a bucket antirollback link, means
for supporting one end of said link adjacent to said control member
for reciprocable and pivotable movement of said link relative to
said control member in response to operation of said bucket and
said lift arm means, and means for supporting said control member
for movement relative to said one end of said link in response to
operation of said bucket operating means whereby engagement of said
one end of said link and said control member prevents rollback of
said bucket past its level position when said lift arm means is
raised in which the reciprocal and pivotable movement of said one
end of said link defines an arcuate path, and in which said control
member includes an arcuate control surface defined by said
path.
9. A material-handling device in accordance with claim 8 including
bucket control linkage interconnecting said bucket and said lift
arm means, and means connecting the other end of said link to said
linkage for movement of said one end of said link towards said
control member during rollback of said bucket and raising of said
lift arm means and for moving said one end of said link away from
said control member during forward roll of said bucket and lowering
of said lift arm means.
10. A material-handling device in accordance with claim 8 in which
said bucket operating means includes a hydraulic cylinder connected
between said bucket and said lift arm means and a hydraulic valve
for controlling operation of said cylinder to alternatively roll
said bucket forward and back, and mechanical linkage means
connecting said control member to said valve for moving said
control member towards said one end of said link in response to
operation of said valve to roll back said bucket and for moving
said control member away from said one end of said link in response
to operation of said valve to roll said bucket forward, whereby
engagement of said link and said control member causes movement of
said control member away from said link to close said valve and
prevent rollback of the bucket past its level position when said
lift arm means are raised.
Description
BACKGROUND OF THE INVENTION
Material-handling devices such as loaders mounted upon and
controlled by various vehicles, are well known. Such loaders
include lift arms pivotally mounted to the vehicle which lift arms
carry a pivotally mounted bucket at their free end. Typically, at
least one hydraulic lift cylinder is connected between the vehicle
or a support thereon and the lift arms to raise and lower the lift
arms. At least one bucket hydraulic cylinder is connected between
the lift arms and the bucket to position the bucket relative to the
lift arms.
A slave cylinder is usually provided to modify the action of the
bucket cylinder under the control of the raising and lowering
movement of the lift arms in order to maintain the bucket at a
substantially level position. A typical self-leveling arrangement
of this type is disclosed in Long U.S. Pat. No. 3,220,580.
Such material-handling devices and systems operate satisfactorily
for their designed purposes. However such arrangements may be
deficient because of a failure to prevent rearward dumping of the
bucket.
When the lift arms are raised, such rearward dumping of the buckets
may present a substantial danger to the operator of the
material-handling device. Thus, there is a requirement and a
serious need for some simple device which can be incorporated into
material-handling devices to introduce the desired safety factor
and prevent the possibility that the bucket might inadvertently be
actuated in fashion to cause rearward dumping of the bucket when
the lift arms are raised.
SUMMARY OF THE INVENTION
The present invention is directed to a positive, mechanical, bucket
antirollback mechanism for use in material-handling devices,
particularly those of the heavy duty type. The antirollback
mechanism is designed to limit operation of the bucket operating
lever to prevent rollback of the bucket past its level position
when the lift arms are raised above a selected height.
It can be appreciated that as the lift arms are raised, the
position of the bucket relative to the lift arm changes while the
bucket remains level or at any fixed position relative to the
ground. Thus, any antirollback device to be effective must take
into account these varying relationships between the bucket and the
lift arms and be capable of preventing rollback of the bucket past
its level position at any raised position of the lift arm.
At the same time, it is sometimes desirable to roll the bucket back
past its level position when the lift arms are lowered into digging
or dozing position. When the lift arms are so lowered, there is no
danger of dumping the load onto the operator and rollback beyond
level position is of assistance in breaking out the bucket as its
digs into a load.
In accordance with the present invention there is provided a
mechanical antirollback mechanism which prevents rearward tilting
of the bucket past its level position when the lift arms are
raised, but which permits the desired rollback of the bucket when
the lift arms are in their lowered position. In accordance with the
present invention there is provided a rigid antirollback link in
the form of a rod of fixed length one end of which is pivotally
connected to the bucket control linkage interconnecting the bucket,
the lift arms and the bucket control cylinders. This bucket control
link is slideably supported in a sleeve the end of which remote
from the bucket control linkage is pivotally supported adjacent to
the pivot point of the lift arms. The free end of the rod extends
beyond the end of the sleeve and travels in an arcuate path as the
lift arms are raised with the bucket, remaining in a fixed position
relative to the ground e.g., when the bucket remains in its level
position.
An antirollback control member is pivotally mounted adjacent to the
free end of the antirollback rod and has a control surface formed
therein substantially identical to the curved path traced by the
end of the control rod during raising of the lift arms. This
control member is mechanically connected to the bucket operating
lever and the position of the control member is governed by the
position of the bucket operating lever.
Thus, the control member is moved towards the free end of the
control rod as the operating lever is moved to its first or bucket
rollback operating position while the control lever is pivoted away
from the free end of the control rod when the operating lever is
moved into its second or bucket dump operating position. The
movements of the rod and control member relative to each other are
such that the end of the rod is moved towards the control member as
the lift arms are raised and moved away from the control member as
the lift arms are lowered. In addition the control rod is moved
towards the control member as the bucket is rolled back and is
moved away from the control member as the bucket is moved forward
into the dump position.
Thus, in operation, as the lift arms are raised, the rod is moved
towards the control member. The rod engages the arcuate control
surface of the control member as the bucket approaches its level
position to prevent further rollback of the bucket past its level
position.
Additionally, if the operating lever is moved into its bucket
rollback operating position, the control member is moved towards
the rod if the bucket is not already at its level position. If the
bucket is level, the control member immediately engages the free
end of the rod to prevent further movement of the control member
towards the rod. In fact, engagement of the rod with the control
member forces the control member away from the rod and, therefore,
the operating lever out of its bucket rollback position into a
neutral position.
Thus, it is clear that the relative position and movements of the
control member and antirollback control rod are such as to prevent
inadvertent, erroneous operation of the operating lever to roll
back the bucket past its level position when the lift arms are
raised. Simultaneously, this antirollback mechanism supplements the
hydraulic self-leveling control to prevent bucket rollback past the
level position as the lift arms are raised.
Numerous other advantages and features of the present invention
will become readily apparent from the following detailed
description of the invention and of one embodiment thereof, from
the claims and from the accompanying drawings in which each and
every detail shown is fully and completely disclosed as a part of
this specification in which like numerals refer to like parts.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevation of the material-handling device, showing
in solid lines the bucket and lift arms in the digging or lowered
position and in dotted lines the lift arms in the raised position
with the bucket in the level and dump positions;
FIG. 2 is an enlarged side view showing in more detail the
antirollback mechanism in various positions of the bucket and lift
arm;
FIG. 3 is a plan view partially in section, taken along lines 3-3
of FIG. 2;
FIG. 4 is a partial enlarged side view showing the control member
and its connection to the operation lever; and
FIG. 5 is an enlarged side view of the control member showing the
relationship of its control surface to the path followed by the
free end of the antirollback rod.
DETAILED DESCRIPTION
Referring now to the drawings, there is shown a material-handling
device 10 including a loader mechanism 12 mounted on the front end
of a tractor 14. The loader mechanism includes a main frame 16 that
is attached to the tractor by any suitable means. The main frame
serves as the main support member for the loader mechanism and
includes a pair of uprights 18 (only one being shown) on opposite
sides of the tractor. The uprights 18 are connected at their upper
ends by a pivot shaft 20. Although only one side of the loader
mechanism 12 is shown, it should be understood that the various
components are normally present on both sides of the tractor
14.
The loader mechanism 12 consists of a pair of lift arms 22
pivotally connected to the upper end of the uprights 18 by the
pivot shaft 20. A bucket 24 is pivotally connected to the forward
end of the lift arms 22.
Each lift arm 22 is pivoted about the pivot shaft 20 by operation
of a hydraulic cylinder 26 through the extension or retraction of a
piston rod 28 extending outwardly from the cylinder 26. The lower
end 30 of each lift arm cylinder 26 is pivotally connected to the
lower portion of an upright 18 while the outer end 32 of each lift
arm cylinder piston rod 28 is pivotally secured to an intermediate
portion of a lift arm 22.
Hydraulic pressure may be applied to either end of the cylinders 26
by operating the lift arm control valve 33. When hydraulic pressure
is applied to the piston end of the hydraulic lift arm cylinders
26, the lift arms 22 are raised by pivoting about the pivot shaft
20. Conversely, when pressure is applied to the rod end of the lift
arm hydraulic cylinders 26, the lift arms 22 are pivoted in an
opposite direction to lower the bucket 24 attached to the end of
the arms.
The bucket 24 is pivoted relative to the lift arms 22 by at least
one hydraulic bucket cylinder 34. The piston rod 36 of the bucket
cylinder 34 is connected to the lift arms 22 near the end thereof
while the cylinder 34 itself is coupled to the bucket 24 through a
bucket control linkage 38. This bucket linkage is identical for
both lift arms and therefore only one such arrangement will be
described.
The bucket control linkage 38 includes a forward bucket link 40 one
end of which is pivotally secured to the bucket 24 and the opposite
end of which is pivotally connected to the end of a rear bucket
link 42. The opposite end of the rear bucket link 42 is pivotally
connected to an intermediate portion of the lift arms 22. It can
thus be seen that pivotal movement of the rear bucket link 42
causes pivotal movement of the bucket 24 relative to the lift arms
22. To effectuate movement of the rear bucket link 42, the bucket
hydraulic cylinder 34 is pivotally connected thereto intermediate
its ends.
Application of hydraulic pressure to the rod end of the bucket
cylinder 34 causes the bucket 24 to pivot forwardly relative to the
lift arms 22. Conversely, application of hydraulic pressure to the
piston end of the bucket cylinder 34 causes the bucket 24 to pivot
rearwardly, i.e., to rollback from the dump position through the
dig position to the carry or level position. It is, of course,
understood that the two bucket control linkages 38 operate
simultaneously to bring about the desired results.
It can be appreciated that when the lift arms 22 are raised, the
bucket 24, if it remains in a fixed position relative to the arms,
would tend to tilt rearwardly. As a result, a load in the bucket 24
would be dumped back onto the tractor and onto the operator, if
such were the case. A slave cylinder 44 connected between the lower
region of an upright 18 and the rear end of a lift arm 22 provides
self-leveling of the bucket 24 as the lift arms 22 are raised. The
leveling action of the arrangement is functionally similar to that
shown in FIG. 2 of the Long U.S. Pat. No. 3,220,580.
In the arrangement of Long U.S. Pat. No. 3,220,580,, control of the
hydraulic bucket cylinder 34 may be effected independently of the
position of the lift arms 22. As a result the bucket cylinder 34
can be operated fully in either direction at any position of the
lift arms 22. In the event of operator error, the bucket 24 could
be tilted rearwardly, i.e., rolled back, thereby dumping a load on
the vehicle if the lift arms 22 are raised. This can be quite
dangerous to the operator particularly when large loads are being
handled.
In accordance with the present invention, there is provided a
mechanical interlock effective when the lift arms 22 are raised
above a selected position to prevent rearward tilting or rollback
of the bucket 24 past its level position while permitting forward
tilting of the bucket for dumping of the load. This mechanism
includes an antirollback control link 46 having a control rod 48
and a sleeve 50. The rod is pivotally connected to the rear bucket
link 42 intermediate the pivotal connections thereof to the lift
arms 22 and to the bucket cylinder 34. The rod 48 is slideably
supported in the sleeve 50. The end 52 of the sleeve 50 closest to
the bucket control linkage 38 is free to move along the rod, while
the other end 54 of the sleeve 50 terminates short of the free end
56 of the rod 48 in order to eliminate interference with the rod
end 56. The sleeve 50 is attached to a bracket 58 which is
pivotally mounted to the upright 18 at a point beyond the free end
56 of the rod 48 and adjacent to the pivot shaft 20 about which the
lift arms 22 pivot.
This arrangement allows the rod 48 to move rearwardly as the lift
arms 22 are raised and as the bucket 24 is rolled back. Conversely,
the rod 48 moves forwardly when the bucket 24 is rolled forward and
when the lift arms 22 are lowered.
An antirollback control member 60 is pivotally mounted on the
upright 18 and is provided with an arcuate control surface 62
disposed adjacent to the free end 56 of the antirollback rod 48.
The antirollback control pivot shaft is connected to a bucket
operating lever 64 through a bucket operating linkage 66 which also
connects the operating lever 64 to the bucket control valve 68 As a
result, when the operating lever 64 is moved into a "first"
position, it operates the bucket control valve 68 to apply
hydraulic pressure to the piston end of the bucket control cylinder
34 thereby causing the bucket 24 to roll back. This rollback of the
bucket moves the control rod 48 towards the control member 60.
Movement of the operating lever 64 into its first position also
operates on the antirollback control member 60 through operating
linkage 66 to pivot the control member 60 forwardly toward the free
end 56 of the antirollback rod 48.
Conversely, when the operating lever 64 is moved into its second or
bucket dump position, it operates the bucket control valve 68 to
apply hydraulic pressure to the rod end of the bucket control
cylinder 34, thereby causing the bucket 24 to pivot forwardly, and
causing the rod 48 to move away from the control member 60.
Movement of operating lever 64 into its second position also causes
the antirollback control member 60 to pivot away from the free end
56 of the antirollback rod 48.
The arcuate control surface 62 of the antirollback control member
60 is selected to coincide with the path followed by the free end
56 of the antirollback control rod 48 when the lift arms 22 are
raised with the bucket 24 automatically maintained at its level
position. Thus, when the bucket operating lever 64 is in neutral,
the free end 56 of the rod 48 remains closely adjacent to the
arcuate control surface 62 of the antirollback control link as the
lift arms 22 are raised, as can be seen in FIG. 5.
By reference to FIGS. 4 and 5, it can be appreciated that the
relationship of the rod 48 to the control surface of the
antirollback control member 60 prevents additional rollback of the
bucket 24 past its level position. If an attempt were made to move
the operating lever 64 into its first, bucket rollback position,
the control member 60 would be rotated towards the free end 56 of
the rod 48 (clockwise in FIGS. 4 and 5). The control surface 62 of
the control member 60 would engage the end 56 of the rod 48
immediately, thereby preventing movement of the operating lever 64
into the rollback position.
Since the position of the rod 48 varies as a function as a position
of the bucket 24 and lift arms 22, rollback of the bucket 24 moves
the free end 56 of the rod 48 towards the control surface 62 of the
control member 60. Although the antirollback mechanism of the
present invention could operate if one or the other of the control
member 60 or the rod 48 remained stationary, the combined movement
of both the control member 60 and rod 48 is beneficial for a number
of reasons.
Thus, for example, when both the control member 60 and the rod 48
move toward each other during bucket rollback it is quite apparent
that they will make contact quicker than would be the case if one
remained stationary. The movement of both the control member 60 and
rod 48 also results in quicker contact between the two since the
free end 56 of the rod 48 can be positioned closely adjacent to the
control surface 62 of the control member 60 during raising and
lowering of the lift arms.
Furthermore, combined action of both the control member 60 and the
rod 48 provides additional insurance that the antirollback
mechanism will operate properly, since, as explained above, the
free end 56 of the rod 48 engages the control surface 62 of the
control member 60 as the bucket starts to roll back past its level
position. When this occurs, the control member 60 is caused to
rotate counterclockwise (FIG. 4) thereby forcing the operating
lever 64 out of the rollback position to close the bucket control
valve 68 thereby stopping rollback of the bucket.
This relationship can also be used as an auxiliary self-leveling
mechanism should the hydraulic self-leveler fail. Under these
circumstances, the free end 56 of the control rod 48 would engage
the control surface 62 of the control member 60 as the lift arms
are raised without leveling of the bucket. As a result, the control
member 60 would be rotated from its neutral position
counterclockwise to force the operating lever 64 into its dump
position, thereby operating the bucket control valve 68 to pivot
the bucket 24 forwardly to keep the bucket at a level position.
The arrangement of the antirollback control member 60 and rod 48 is
such as to permit dumping of the bucket at any position of the lift
arms 22. When the operating lever 64 is moved into the bucket dump
position, the control member 60 is moved away from the free end 56
of the antirollback rod 48 and simultaneously the forward pivoting
movement of the bucket 24 pulls the control rod 48 away from the
control surface 62 of the antirollback control member 60.
The control member 60 terminates at a point as can be seen by
reference to FIG. 5 which allows the bucket 24 to be rolled past
its level position when the lift arms 22 are below a selected
level. As shown in FIG. 5, the bucket may be rolled back past its
level position up to a point where the lift arms are about at
10.degree. lift, thus permitting the rollback of the bucket desired
for break out of the load.
From the foregoing, it will be observed that numerous variations
and modifications may be effected without departing from the true
spirit and scope of the novel concept of the invention. It is, of
course, intended to cover by the appended claims all such
modifications as fall within the scope of the claims.
* * * * *