U.S. patent application number 12/225297 was filed with the patent office on 2010-09-16 for lift arm of skid steer loader.
Invention is credited to Takeshi Endou, Kazuhisa Satou.
Application Number | 20100232918 12/225297 |
Document ID | / |
Family ID | 38522438 |
Filed Date | 2010-09-16 |
United States Patent
Application |
20100232918 |
Kind Code |
A1 |
Endou; Takeshi ; et
al. |
September 16, 2010 |
Lift Arm of Skid Steer Loader
Abstract
The lift arm of a skid steer loader according to the present
invention has a simple structure. A pair of left and right lift
arms each has a first arm portion and a second arm portion. The
first arm portion is made as an elongated member from components
made from plate metal or the like, and its base end is rotatably
fitted to a support portion which projects upwards at a rear
portion of the main body of the loader. In this second arm portion,
a connection portion, an attachment fitting portion, a horizontal
load bearing portion, and an actuator fitting portion and so on are
integrally formed as one member from cast metal. Furthermore, a
hollow portion is formed in the interior of this second arm
portion, extending from an approximately intermediate portion
thereof to its base end.
Inventors: |
Endou; Takeshi; ( Saitama,
JP) ; Satou; Kazuhisa; (Saitama, JP) |
Correspondence
Address: |
POSZ LAW GROUP, PLC
12040 SOUTH LAKES DRIVE, SUITE 101
RESTON
VA
20191
US
|
Family ID: |
38522438 |
Appl. No.: |
12/225297 |
Filed: |
March 16, 2007 |
PCT Filed: |
March 16, 2007 |
PCT NO: |
PCT/JP2007/055348 |
371 Date: |
November 18, 2008 |
Current U.S.
Class: |
414/680 |
Current CPC
Class: |
E02F 3/34 20130101; E02F
3/3414 20130101 |
Class at
Publication: |
414/680 |
International
Class: |
E02F 3/38 20060101
E02F003/38 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 22, 2006 |
JP |
2006-078102 |
Claims
1. A lift arm of a skid steer loader, comprising: a first arm
portion, a base end of which is rotatably supported at a rear
portion of a loader main body, and the other end of which is formed
so as to extend towards a front of said loader main body; and a
second arm portion, a base end of which is fixed to said other end
of said first arm portion, and the other end of which is formed so
as to extend downwards; wherein, in said second arm portion: a
connection portion which is fitted to said other end of said first
arm portion; an attachment fitting portion which is provided at
said other end, and to which a working attachment is rotatably
fitted; an actuator fitting portion which is provided at said base
end, and to which an actuator for actuating said working attachment
is fitted; and a horizontal load bearing portion which is
positioned between said attachment fitting portion and said
actuator fitting portion, which is provided so as to project
towards a side of said loader main body, and which is connected via
a front member to a second arm portion on the opposite side of said
loader main body; are made as a single unit in an integrated manner
from cast metal.
2. The lift arm of a skid steering loader as described in claim 1,
wherein, in said second arm portion a hollow portion is provided
which extends from said connection portion to said horizontal load
bearing portion.
Description
TECHNICAL FIELD
[0001] The present invention relates to a lift arm of a skid steer
loader.
BACKGROUND ART
[0002] Since, with a skid steer loader, the direction is controlled
according to difference between the rotation of the left and the
right wheels, which is the feature by which such a skid steer
loader differs from a wheel loader, and since moreover the lift
arms are supported by the rear portion of the loader main body,
accordingly it is possible to make the total length shorter (Patent
Document #1). Because of this, it is possible to make a skid steer
loader more compact than a wheel loader, and it is possible to make
the radius of its turning circle smaller. Due to this, a skid steer
loader is appropriately employed for civil engineering work in a
comparatively restricted space such as, for example, landscaping or
the like.
[0003] It should be understood that, while the lift arm of a
conventional skid steer loader is built up from a group of
components which are formed of rolled steel, among construction
machines other than skid steer loaders, some working machines are
also known in which a portion thereof is manufactured from cast
metal (Patent Documents #2 and #3).
[0004] Patent Document #1: Japanese Laid-Open Patent Publication
Heisei 6-33476.
[0005] Patent Document #2: Japanese Laid-Open Patent Publication
Heisei 8-113960.
[0006] Patent Document #3: Japanese Laid-Open Patent Publication
2001-303606.
SUMMARY OF THE INVENTION
Problem at the Solution of which the Invention is Directed
[0007] According to the above, with a skid steer loader, the radius
of the turning circle is smaller as compared to a wheel loader, and
it is also possible to perform a spin turn. Thus a skid steer
loader, which is more compact and moreover whose ease of use is
higher as compared to a wheel loader, can be utilized for various
applications, such as ground leveling work or the like, in
comparatively restricted spaces.
[0008] In some cases, such as, for example, when work such as
digging or cutting work or loading work is being performed with a
bucket which is provided at the end of a lift arm, and in some
other cases, ground leveling work or the like may be performed by
employing the side of the bucket or the like. In other words since,
with a skid steer loader, the same working attachment may be used
for various different applications, in which respect a skid steer
loader is different from a wheel loader, accordingly, in addition
to the load at the end of the lift arm in the vertical direction, a
comparatively large load may also be experienced from the
horizontal direction. Due to this, various structures must be
provided at the end of the lift arm of a skid steer loader, i.e. a
structure for sustaining loads from the vertical direction and a
structure for sustaining loads from the horizontal direction, and
accordingly the construction becomes complicated.
[0009] It should be understood that although, in Patent Documents
#2 and #3 described above, it is disclosed to make a portion of a
working machine out of cast metal, since these documents relate to
a wheel loader and to an oil pressure shovel, accordingly they are
not considered to have any specific connection with the particular
technical nature of a skid steer loader such as described
above.
[0010] The present invention has been conceived of in consideration
of the problem described above, and its objective is to provide a
lift arm of a skid steer loader, with which the construction of the
lift arm can be simplified. Another objective of the present
invention is to provide a lift arm of a skid steer loader, which is
adapted so that it is possible to simplify and to lighten the
construction at the end of the lift arm.
Means for Solving the Problems
[0011] The lift arm of a skid steer loader according to the present
invention includes a first arm portion, a base end of which is
rotatably supported at a rear portion of a loader main body, and
the other end of which is formed so as to extend towards the front
of the loader main body, and a second arm portion, a base end of
which is fixed to the other end of the first arm portion, and the
other end of which is formed so as to extend downwards. And, in the
second arm portion, a connection portion which is fitted to the
other end of the first arm portion, an attachment fitting portion
which is provided at the other end, and to which a working
attachment is rotatably fitted, an actuator fitting portion which
is provided at the base end, and to which an actuator for actuating
the working attachment is fitted, and a horizontal load bearing
portion which is positioned between the attachment fitting portion
and the actuator fitting portion, which is provided so as to
project towards the side of the loader main body, and which is
connected via a front member to a second arm portion on the
opposite side of the loader main body, are made as a single unit in
an integrated manner from cast metal. Furthermore, at the second
arm portion, it is also possible to provide a hollow portion which
extends from the connection portion to the horizontal load bearing
portion.
Benefits of the Invention
[0012] According to the present invention, it is possible to
simplify the construction of the lift arm, since the lift arm is
separated into the first arm portion and the second arm portion,
and the second arm portion, which is positioned towards the end
thereof, is formed in one piece from cast metal.
[0013] Moreover, by providing the hollow portion to the second arm
portion, it is possible to lighten the second arm portion.
Preferred Embodiment for Implementation of the Invention
[0014] In the following, an embodiment of the present invention
will be explained based upon the drawings. In this embodiment, as
described in detail hereinafter, the end portions of the lift arms,
in other words the portions thereof forward from the regions where
the actuator cylinders are fitted thereto, are formed from cast
metal as one piece members. First of all, this skid steer loader as
a whole will be explained, and then the construction of its lift
arms will be explained.
[0015] FIG. 1 is a side view of a skid steer loader 1. And FIG. 2
is a plan view of this skid steer loader 1. As will be described
hereinafter, this skid steer loader 1 comprises, for example, a
loader main body 2, front wheels 3A and rear wheels 3B, a driver's
seat 4, a support portion 5, lift arms 6, arm cylinders 7, an
attachment coupler 8, a bucket 9, and the like.
[0016] The loader main body 2 constitutes the vehicle body of this
skid steer loader 1, and front wheels 3A, 3A are provided to its
front on the left and right sides so as to be rotatable, while rear
wheels 3B, 3B are provided to its rear on the left and right sides
so as likewise to be rotatable. The rotational speeds of the left
and right front wheels 3A and rear wheels 3B can each be controlled
independently. By varying the rotational speeds of the left and
right front wheels 3A and rear wheels 3B, it is possible to control
the attitude of the loader main body 2, and it is also possible to
perform a spin turn. This type of rotational speed control of the
vehicle wheels 3A and 3B can be performed with an actuation lever
device at the driver's seat 4.
[0017] The driver's seat 4 is provided at an upper portion of the
loader main body 2, positioned towards the front thereof. Except
for its front surface, the other three surfaces of this driver's
seat 4 (its left and right surfaces and its rear surface) are
covered with net guards 4A. The operator gets into the driver's
seat 4, and gets out therefrom, by using its front surface, which
opens. Furthermore, at least a portion at the upper surface of the
driver's seat 4 is covered with a ceiling portion 4B which is
formed as a grid. It should be understood that it is not necessary
to cover over all of the three surfaces of the driver's seat 4
apart from its front surface with the net guards 4A; any structure
may be utilized, provided that the field of vision can be ensured,
and moreover that the operator is able to mount and dismount.
[0018] An engine and the like is housed in the rear portion of the
loader main body 2; and furthermore, at left and right rear
portions of the loader main body 2 on both its sides, support
portions 5, 5 for supporting the base ends of lift arms 6,6 are
each provided so as to extend upwards. The base ends of lift arms 6
are supported by pins 12 at the upper ends of these support
portions 5, so as to be rotatable.
[0019] The lift arms 6 are rotated in the upwards and downwards
direction by the extension and retraction operation of arm
cylinders 7. The base ends of these arm cylinders 7 are rotatably
supported via pins 11 at the lower sides of the support portions 5,
and the other ends of the arm cylinders 7 are rotatably supported
via pins 13 at approximately the central portions of the lift arms
6. By the arm cylinders 7 extending, the lift arms 6 are displaced
in the upward direction, as shown by the double dotted broken lines
in FIG. 1. And, by the arm cylinders 7 retracting, the lift arms 6
are displaced downwards, as shown by the solid lines in FIG. 1.
[0020] The ends of the lift arms 6 are curved downwards towards the
front of the loader main body 2, and an attachment coupler 8 is
provided thereto. This attachment coupler 8 is a device for fitting
various types of removable attachment, such as a bucket, a fork, a
sweeper, or the like.
[0021] A bucket 9 which is fitted to the ends of the lift arms 6
via the attachment coupler 8 is an example of a working attachment,
but the present invention is not limited thereto. When the lift
arms 6 are lowered to their lowermost positions, for example, the
angle .theta.1 between the front surface of the bucket 9 and the
surface of the ground may be about 30.degree.. Furthermore, as
shown by the dotted lines in FIG. 1, when a load in the bucket 9 is
to be loaded upon a truck or the like, the angle .theta.2 between
the front surface of the bucket 9 and the surface of the ground may
be, for example, about 45.degree..
[0022] In other words, as compared with a typical wheel loader, the
angle to which the bucket 9 can rotate is set to be greater.
Although a skid steer loader 1 is made to be more compact than a
wheel loader, since the height of the carrier such as a truck upon
which material is to be loaded does not change, accordingly the
angle to which the bucket 9 can rotate is set to be greater, so
that it is possible to perform loading work smoothly.
[0023] Here, it is desirable for the distance L1 between the center
of gravity of the bucket 9 and the centers of the front wheels 3A
to be set to be as short as possible. If L1 is set to be long, i.e.
if the amount by which the lift arms 6 project forwards of the
loader main body 2 is long, then, in order to obtain a balance, it
is necessary to mount a balance weight to the rear portion of the
loader main body 2. If such a balance weight is mounted, then the
weight of the skid steer loader 1 increases, its overall dimensions
are increased, and its working ability is decreased. Accordingly,
it is desirable for L1 to be set to be as short as possible.
[0024] However, the shorter L1 is set, the less easy does it become
to ensure sufficient space for reinforcing the left and right lift
arms 6, 6 with Z-shaped link members or the like. Since the left
and right lift arms 6, 6 are curved somewhat downwards towards the
loader main body 2, accordingly the gap between the ends of these
lift arms 6, 6 and the front end of the loader main body 2 becomes
short, and the space for reinforcing them with link members or the
like becomes tight. Furthermore, since the operator gets into and
gets out of this skid steer loader 1 through the front of the
loader main body 2, which is different from the case with a wheel
loader, accordingly it is also necessary to employ a construction
in which no impediment is presented to the operator getting in and
out.
[0025] Thus, in this embodiment, as will be described subsequently,
with this skid steer loader 1 in which there is a scarcity of space
between the lift arms 6, 6 for reinforcement, a new construction
for the lift arms 6 is proposed, with which it is possible
sufficiently to withstand horizontal load applied to the lift arms
6, and with which, moreover, it is possible to anticipate
lightening thereof.
[0026] FIG. 3 is a perspective view of the lift arms 6, and FIG. 4
is a plan view of these lift arms 6. As shown in the perspective
view of FIG. 3, one of these lift arms 6 is made from a first arm
portion 21 and a second arm portion 22. The first arm portion 21 is
formed from a material such as steel plate or the like as an
elongated member having a generally rectangular shape in cross
section, while the second arm portion 22 is formed in a curved
shape from cast metal such as, for example, SC450W or the like.
First the structure of the first arm portion 21 will be explained,
and next the structure of the second arm portion 22 will be
explained.
[0027] A base end 21A of the first arm portion 21 is fitted via one
of the pins 12 to the upper side of one of the support portions 5
so as to be freely rotatable, while its other end 21B is fixed to a
base end 22A of the second arm portion 22 using a fixing means such
as welding or the like. At an approximately intermediate portion of
the first arm portion 21, a cylinder fitting portion 21C is
provided so as to extend downwards. And the end of one of the arm
cylinders 7 is rotatably supported upon this cylinder fitting
portion 21C via one of the pins 13.
[0028] The second arm portion 22, while being fitted to the end 21B
of the first arm portion 21, is curved downwards so as to cover the
upper side of one front wheel 3A of the loader main body 2. By
contrast to the first arm portion 21 which is made by welding
together a plurality of metallic plates, this second arm portion 22
is made as one unitary piece of cast metal.
[0029] In this second arm portion 22, there are integrally formed
from cast metal a connection portion 22A, an attachment fitting
portion 22B, a horizontal load bearing portion 22C, and an actuator
fitting portion 22D, each of which will be described
hereinafter.
[0030] The connection portion 22A is provided as positioned at the
base end of the second arm portion 22, and it is fitted to the end
21B of the first arm portion 21. And the attachment fitting portion
22B is provided as positioned at the other end of the second arm
portion 22, with the bucket 9 being fitted to it via the attachment
coupler 8.
[0031] The horizontal load bearing portion 22C is positioned at an
approximately intermediate portion of the second arm portion 22,
and is provided so as slightly to project to the inside (i.e. to
the side of the loader main body 2). One end of a front member 30,
which is made by, for example, metallic plate processing or the
like, is connected to the projecting end side of this horizontal
load bearing portion 22C. In other words, the left and right second
arm portions 22, 22 are connected together via the front member 30
which is connected to their horizontal load bearing portions 22C.
Accordingly, the front member 30 may also, for example, be termed
an arm connection portion. Furthermore, a reinforcement portion
22C1 is provided upon the upper surface of the horizontal load
bearing portion 22C, extending slantingly upwards towards the inner
side of the second arm portion 22. Load which is imposed upon the
second arm portion 22 from the horizontal direction (the transverse
direction to the loader main body 2) is transmitted from the
horizontal load bearing portion 22C via the front member 30 to the
second arm portion 22 on the other side. The reinforcement portion
22C resolves the load which the second arm portion 22 receives from
the horizontal direction into component forces in the vertical
direction and in the horizontal direction, and prevents the stress
being concentrated in any particular spot.
[0032] The actuator fitting portion 22D is provided as positioned
towards the base end of the second arm portion 22, and so as to
project somewhat upwards. This actuator fitting portion 22D is a
lug for rotatably attaching the base end of an actuator cylinder
not shown in the figure.
[0033] Furthermore, ribs 22E may be provided upon the surface of
the second arm portion 22 as appropriate. In the example shown in
the figures, the rigidity of the end 22B of the second arm portion
22 is enhanced by providing a plurality of ribs 22E as positioned
towards the end 22B.
[0034] FIG. 5 is a side view of a lift arm 6 as seen from the
exterior of the loader main body 2, and FIG. 6 is a side view of
the end portion of a lift arm 6 as seen from the interior of the
loader main body 2. As already explained, this lift arm 6 is built
in a hybrid construction, and includes an elongated first arm
portion 21 which is made by processing metal plate or the like, and
a second arm portion 22 which is made from cast metal. And the
second arm portion 22 is made as a single unitary component, in
which a connection portion 22A, an attachment fitting portion 22B,
a horizontal load bearing portion 22C, and an actuator fitting
portion 22D and so on are formed in an integrated manner.
[0035] Furthermore, as shown in the sectional view of FIG. 7, in
this embodiment, a hollow portion 22F is provided in the interior
of the second arm portion 22. This hollow portion 22F is formed so
as to extend from the base end of the second arm portion 22 (i.e.
the connection portion 22A) to a point P which is roughly
intermediate along the second arm portion 22. This point P may be,
for example, set so as to match the lower edge of the horizontal
load bearing portion 22C.
[0036] Naturally, it is not absolutely required for the hollow
portion 22F to be provided as far as the lower edge of the
horizontal load bearing portion 22C; it would be acceptable for the
length L2 of this hollow portion 22F to be shorter. However, the
shorter the length L2 of the hollow portion 22F (its length in the
longitudinal direction from the connection portion 22A towards the
attachment fitting portion 22B) is made, the more is the weight of
the second arm portion 22 increased.
[0037] The horizontal cross sectional size of this hollow portion
22F is set from the point of view of ensuring the rigidity of the
portion which includes this hollow portion 22F. In other words, the
thickness t of the second arm portion over the range where the
hollow portion 22F is provided is set to a value at which the
necessary rigidity thereof is assured.
[0038] In this embodiment, as described above, the lift arm 6 is
made in a construction which is divided into two portions, the
first arm portion 21 and the second arm portion 22; and, moreover,
the second arm portion 22 is made as a unitary member from cast
metal. Accordingly, it is possible to simplify the structure of the
second arm portion 22, whose construction can easily become
complicated, and, as a result, it is possible to simplify the
overall structure of the lift arm 6. Due to this, it is possible to
reduce the number of component parts of the lift arm 6, so that it
is possible to enhance the production efficiency and to reduce the
manufacturing cost.
[0039] In other words, this skid steering loader 1 is a device
which can be handily used in various applications in a
comparatively restricted space, in which characteristic it differs
from a wheel loader, and it has the technical nature that not only
is a load imposed upon it in the vertical direction, but also
comparatively high loads may be applied to it in the horizontal
direction as well.
[0040] Moreover, with a skid steer loader 1, in order to enhance
the working characteristics in a comparatively restricted space,
there is a demand from the market to make it more compact and
lighter. Accordingly, as shown in FIG. 1, the distance L1 between
the center of gravity of the bucket 9 and the centers of the front
wheels 3A is set to be short, and therefore the availability of
space for providing reinforcement structures like Z-shaped link
members or the like becomes poor.
[0041] Under this type of limitation, with a skid steer loader 1,
it is necessary to provide lift arms 6, 6 which have a structure
and so on which takes effective advantage of the small space
available, in order to provide a structure for fitting an actuator
such as the bucket 9 or the like, and in order adequately to
support loads both in the vertical direction and also in the
horizontal direction. With prior art skid steer loaders, since
various groups of components made from plate metal have been
disposed in this limited space, the construction of the lift arms
has become complicated, and the efficiency of the assembly process
for them has also been low. By contrast, with this embodiment of
the present invention, since the second arm portion 22 which is
made as a single unitary member from cast metal is disposed in this
limited space, it is possible to simplify the construction and to
enhance the production efficiency, and it is also possible to
reduce the manufacturing cost.
[0042] Moreover, in this embodiment, it is arranged to provide the
hollow portion 22F within the second arm portion 22 while still
ensuring adequate rigidity for the second arm portion 22. Due to
this, it is possible to anticipate that the second arm portion 22
will be lightened.
[0043] It should be understood that the present invention is not
limited to the embodiment described above. It would be possible for
a person skilled in the art to make various additions or changes or
the like, within the range of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0044] FIG. 1 is a side view of a skid steer loader;
[0045] FIG. 2 is a plan view of this skid steer loader;
[0046] FIG. 3 is a perspective view of lift arms thereof;
[0047] FIG. 4 is a plan view of these lift arms;
[0048] FIG. 5 is a side view of a lift arm as seen from the
exterior;
[0049] FIG. 6 is a side view of the end portion of a lift arm as
seen from the interior; and
[0050] FIG. 7 is a sectional view of a second arm portion.
EXPLANATION OF THE REFERENCE SYMBOLS
[0051] 1 . . . skid steer loader, 2 . . . loader main body, 3A . .
. front wheels, 3B . . . rear wheels, 4 . . . driver's seat, 4A . .
. net guards, 4B . . . ceiling portion, 5 . . . support portions, 6
. . . lift arms, 7 . . . arm cylinder, 8 . . . attachment coupler,
9 . . . bucket, 11, 12, 13 . . . pins, 21 . . . first arm portions,
21A . . . base ends, 21B . . . end portions, 21C . . . cylinder
fitting portions, 22 . . . second arm portions, 22A . . .
connection portions, 22B . . . attachment fitting portions, 22C . .
. horizontal load bearing portions, 22C1 . . . reinforcement
portions, 22D . . . actuator fitting portions, 22E . . . ribs, 22F
. . . hollow portion, 30 . . . front member.
* * * * *