U.S. patent application number 13/155649 was filed with the patent office on 2012-12-13 for work machine.
Invention is credited to Jarrod HYDER.
Application Number | 20120315120 13/155649 |
Document ID | / |
Family ID | 47293337 |
Filed Date | 2012-12-13 |
United States Patent
Application |
20120315120 |
Kind Code |
A1 |
HYDER; Jarrod |
December 13, 2012 |
WORK MACHINE
Abstract
A work machine having: a working part; a holding part for
holding the working part; and an operating part for rotating the
working part around the holding part; further comprising: an angle
sensing means for sensing the angle of the working part from the
horizontal; and a controller for adjusting and holding the position
of the working part by use of the operation means based on the
angle sensing means.
Inventors: |
HYDER; Jarrod; (Adairsville,
GA) |
Family ID: |
47293337 |
Appl. No.: |
13/155649 |
Filed: |
June 8, 2011 |
Current U.S.
Class: |
414/699 |
Current CPC
Class: |
E02F 9/2004 20130101;
E02F 9/2025 20130101; E02F 3/433 20130101; E02F 3/627 20130101;
E02F 3/34 20130101 |
Class at
Publication: |
414/699 |
International
Class: |
E02F 3/36 20060101
E02F003/36 |
Claims
1. A work machine having: a working part; a holding part for
holding the working part; and an operating part for rotating the
working part around the holding part; further comprising: an angle
sensing means for sensing the angle of the working part from the
horizontal; and a controller for adjusting and holding the position
of the working part by use of the operation means based on the
angle sensing means.
2. The work machine as set forth in claim 1 wherein the angle
sensing means is installed on the working part.
3. The work machine as set forth in claim 1 wherein the angle
sensing means is installed on the back part of the working
part.
4. The work machine as set forth in claim 1 wherein the angle
sensing means is installed on the side part of the working
part.
5. The work machine as set forth in claim 1, further comprising: a
driver's seat for the operator, a working part control lever
installed at the side of the driver's seat, for turning the working
part around by the operator, and an angle control switch equipped
on the working part control lever, for starting adjusting and
holding the working part to a target angular position.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a work machine, such as an
agricultural machine or a construction machine, having a bucket,
booms supporting the bucket, and dump cylinders for rotating the
bucket around the booms.
[0003] 2. Description of the Relate Art
[0004] In conventional work machines having a working part such as
a bucket, an operator operates the bucket by use of a bucket
control lever. In other words, the bucket is operated by the
operator manually. Therefore, during operation, it is difficult for
the operator to recognize the exact angular position of the bucket.
To address this problem, patent publications, such as WO2002/040783
and U.S. Pat. No. 5,887,365 have disclosed new methods. These
inventions have a control unit that controls automatic bucket
operation, and the control unit recognizes the angular position of
the bucket. Then, the control unit adjusts the bucket position
according to a target slope angle and a target depth of
excavation.
Problem to be Solved by the Invention
[0005] During excavation work, it is sometimes necessary to keep a
loaded bucket level. However, it is difficult for an unskilled
operator (a driver) to do so. The two above-mentioned patent
publications do not present the solution for this problem.
Therefore, this invention offers a work machine, which is able to
keep a loaded bucket level easily.
SUMMARY OF THE INVENTION
Means to Solve the Problem
[0006] A work machine having: a working part; a holding part for
holding the working part; and an operating part for rotating the
working part around the holding part; further comprising: an angle
sensing means for sensing the angle of the working part from the
horizontal; and a controller for adjusting and holding the position
of the working part by use of the operation means based on the
angle sensing means.
[0007] In one embodiment, the invention may offer the work machine
wherein the angle sensing means is installed on the working
part.
[0008] In one embodiment, the invention may offer the work machine
wherein the angle sensing means is installed on the back part of
the working part.
[0009] In one embodiment, the invention may offer the work machine
wherein the angle sensing means is installed on the side part of
the working part.
[0010] In one embodiment, the invention may offer the work machine
further comprising: a driver's seat for the operator, a working
part control lever installed at the side of the driver's seat, for
turning the working part around by the operator, and an angle
control switch equipped on the working part control lever, for
starting adjusting and holding the working part to a target angular
position.
Advantages of the Invention
[0011] The invention offers a work machine having: a working part;
a holding part for holding the working part; and an operating part
for rotating the working part around the holding part;
[0012] further comprising: an angle sensing means for sensing the
angle of the working part from the horizontal; and a controller for
adjusting and holding the position of the working part by use of
the operation means based on the angle sensing means. Therefore,
the bucket can be easily kept level by even an unskilled operator
(a driver).
[0013] In one embodiment, the invention offers the work machine
wherein the angle sensing means is installed on the working part.
Therefore, the angle position of the working part can be easily
sensed by the angle sensing means.
[0014] In one embodiment, the invention offers the work machine
wherein the angle sensing means is installed on the back part of
the working part. Therefore, the angle position of the working part
can be easily sensed by the angle sensing means.
[0015] In one embodiment, the invention offers the work machine
wherein the angle sensing means is installed on the side part of
the working part. Therefore, the angle position of the working part
can be easily sensed by the angle sensing means.
[0016] In one embodiment, the invention offers the work machine
further comprising: a driver's seat for the operator, a working
part control lever installed at the side of the driver's seat, for
turning the working part around by the operator, and an angle
control switch equipped on the working part control lever, for
starting adjusting and holding the working part to a target angular
position. Therefore, the working part angle control can be easily
operated with the working part control lever while the working part
is operated.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] [FIG. 1] A front perspective view of a tractor (a work
machine) with a front loader as a first embodiment of the
invention.
[0018] [FIG. 2] (a) is a back view of the bucket, (b) is a side
view from "B" in (a), (c) is a side view of the hitch, and (d) is a
section view from "X" in (c).
[0019] [FIG. 3] (a) is a front view of the boom control lever and
the bucket control lever, (b) is a side view of the bucket control
lever from "A" in (a), (c) is a side view of the boom control lever
from "A" in (a).
[0020] [FIG. 4] A hydraulic circuit in the first embodiment.
[0021] [FIG. 5] A block diagram of the main part.
[0022] [FIG. 6] A flow chart of the automatic bucket level control
process.
[0023] [FIG. 7] (a) is a back view of the bucket, (b) is a side
view from "C" in (a).
[0024] [FIG. 8] A front perspective view of the main features of a
tractor (a work machine).
[0025] [FIG. 9] (a) is a front view of the boom-bucket control
lever, (b) is a plane view of (a), (c) is a right-side view of the
boom-bucket control lever, (d) is a front view of the boom-bucket
control lever.
[0026] [FIG. 10] A hydraulic circuit.
[0027] [FIG. 11] A block diagram of the main part.
DETAILED DESCRIPTION OF THE INVENTION
Best Mode of Embodying the Invention
[0028] The best mode of embodying the invention is described below
with reference to specific figures. FIG. 1 shows a front
perspective view of the tractor 10 (a work machine). The tractor 10
is composed of front tires 14, rear tires 15 and a front loader 16.
In this specification, `front` is defined as the direction when the
tractor 10 is going forward, and `back` as the direction when the
tractor 10 is going backward. Furthermore, `left` is defined as the
left side when the tractor 10 is going forward, and `right` is
defined as the right side when the tractor 10 is going forward.
[0029] A hood 12 is put in the front part of the tractor 10. A tank
of gas and an engine (not illustrated) are installed under the hood
12. A frame 41 is put in the lower part of the tractor 10, and the
engine is mounted on the frame 41. The power of the engine is
transmitted to front tires 14 and rear tires 15 through a
transmission (not illustrated). The power of the engine is also
used for a hydraulic pump, which is described below.
[0030] A driver's seat 17, on which a driver sits when operating
the tractor 10, is at the rear part of the tractor 10. A steering
wheel 18, a monitor (not illustrated) etc. are in front of the
driver's seat 17. The monitor is to show driving speed, fuel level,
etc. and also to give an alarm when a tilt sensor (described below)
is not working. A bucket control lever (a working part control
lever) 19 and a boom control lever 20 are installed at the right
side of the driver's seat 17. A transmission (not illustrated) for
changing gears of the tractor 10 is under the driver's seat 17.
[0031] A floor 13 is installed in front of the driver's seat 17.
The floor 13 is composed of a pair of plane parts of the floor 13a
and a projection part of the floor 13b. The two plane parts of the
floor 13a are made plane and board-like. The projection part of the
floor 13b is installed between the two plane parts of the floor
13a. The projection part of the floor 13b and the two plane parts
of the floor 13a are coupled with each other by bolts etc. The
projection part of the floor 13b bends upward, and a driving shaft,
which transmits power from the engine to the transmission, is
located under the projection part of the floor 13b.
[0032] Fenders F are mounted on both sides of the driver's seat 17.
The bucket control lever 19 and the boom control lever 20 are at
the fender F at the right side of the driver's seat 17. A Rollover
Protective Structure (ROPS) R, which is an arch-like safety
protective frame, is almost vertically installed at the rear part
of the fenders F.
[0033] A boom holding mechanism 40 for holding the front loader 16
is installed on both sides and in the middle of the tractor 10.
[0034] The front loader 16 is detachable from the tractor 10. The
front loader 16 is composed of a pair of booms (a support part) 21
set up at both sides of the tractor 10, a pair of lift cylinders 23
located at both sides of the main body of the tractor 10, a bucket
(working part) 26 and a pair of dump cylinders (operating part) 24.
The lift cylinders 23 are to move the boom 21 up and down. The
bucket 26 is coupled with the top of the two booms 21. The dump
cylinders 24 are to turn the bucket 26 around the top of the booms
21. The lift cylinders 23 and the dump cylinders 24 are connected
with a hydraulic circuit. This hydraulic circuit is to operate the
lift cylinders 23 and the dump cylinders 24 by hydraulic pumps,
which work by the power from the engine.
[0035] The booms 21 are shaped as an arc and stretch out toward the
front of the tractor 10. The bottom of each of the booms 21 is
coupled with the upper section of the boom holding mechanism 40,
and the two booms 21 (which are located at both sides of the main
body of the tractor 10) are rotatable around the boom holding
mechanism 40. The bucket 26, on the other hand, is coupled with the
two booms 21 by a hitch (a connection part) 25. The hitch 25 is
detachable from the bucket 26, and is rotatable around the top of
the booms 21. A cylinder bracket 27 is welded at the middle section
of each boom 21. The cylinder bracket 27 is set upward from the
boom 21 in its front part, whereas it is set downward from the boom
21 in its rear part.
[0036] The bucket 26 is made of metal. It is comprised of a bottom
part 26bt, a pair of side parts 26s, a rear part 26bk, a back part
26b and a top part 26u. The side parts 26s are vertically installed
at both ends of the bottom part 26bt. The rear part 26bk is
connected to the pair of side parts 26s at both of its ends. The
back part 26b is connected to the rear part 26bk, and it is also
connected to the pair of side parts 26s at both of its ends. A pair
of stays 26A is put on the rear part 26b. A hook bar 26B is fixed
to the pair of stays 26A at its both ends. A tilt sensor (an angle
sensing means) TS is equipped on the right side part 26s.
Alternatively, the tilt sensor TS may be equipped on the left side
part 26s. The tilt sensor TS senses the angle position of the
bucket 26 from the horizontal; in other words, it senses the angle
between an upper edge 26su of the side part 26s and the horizontal.
Alternatively, the tilt sensor TS may sense the angle position of
the bucket 26 from the vertical. The tilt sensor TS is connected to
a controller (later described).
[0037] The hitch 25 is comprised of a pair of trapezoidal metal
plates. Each boom 21 is held at its top between the two metal
plates and is rotatable at Pin P. Each dump cylinder 24 is also
held at its top between the two metal plates and is rotatable at
this point. Pin P is called a rotation center of the hitch 25 and
the bucket 26. A holding part 25A is made at the top edge of the
hitch 25. The holding part 25A is made by cutting the hitch 25 in a
half circle shape. The holding part 25A holds a hook part 26B of
the bucket 26. Therefore, the bucket 26 is connected to the hitch
25 via the holding part 25A. A pair of stays 26A is made of a
rectangular metal plate and is fixed on the rear part 26bk of the
bucket 26.
[0038] Other attachments instead of the bucket 26 can also be
attached to the hitch 25. A harness, which connects between the
tilt sensor TS and the above-mentioned controller, has a connecter.
The harness can be disconnected from the bucket 26 at said
connecter when the bucket 26 is detached. When another attachment
is attached to the hitch 25, the harness is to be connected to the
attachment with the connecter. A swing sensor or a gyro sensor can
be installed in the bucket 26 instead of the tilt sensor TS.
[0039] The bottom of the lift cylinder 23 is coupled with the boom
holding mechanism 40 and is rotatable at the boom holding mechanism
40. The top of the lift cylinder 23 is, on the other hand,
connected to the back part of the cylinder bracket 27 and is
rotatable at the cylinder bracket 27. Each lift cylinder 23 is
installed underneath and parallel to each boom 21.
[0040] The dump cylinder 24 is connected to the front part of the
cylinder bracket 27 and is rotatable at the cylinder bracket 27. On
the other hand, the top of the dump cylinder 24 is coupled with the
top of the hitch 25 and is rotatable at the hitch 25. Each dump
cylinder 24 is installed over each boom 21.
[0041] Therefore, the booms 21 go up (or rotate upward) when the
lift cylinders 23 stretch out, whereas the booms 21 go down (or
rotate downward) when the lift cylinders 23 shrink. On the other
hand, the bucket 26 turns upward when the dump cylinders 24 shrink,
whereas the bucket 26 turns downward when the dump cylinders 24
stretch out.
[0042] The bucket control lever 18 and the boom control lever 20
are illustrated in FIG. 3(a) to FIG. 3(c), and the hydraulic
circuit is illustrated in FIG. 4. The bucket control lever 19 is to
operate the dump cylinders 24 of the front loader 16. The bucket
control lever 19 consists of a grip 19a, a rod 19b and a protection
part 19c. The grip 19a is made of resin and shaped by an injection
molder. The lower part of the rod 19b is held inside the right
fender F. The protection part 19c covers the gap between the rod
19b and the fender F in order to prevent dust from coming inside
the fender F. The protection part 19c is made of a flexible
material to enable it to follow the movement of the rod 19b. The
bucket control lever 19 is connected to a selector valve 50. The
selector valve 50 changes position when the bucket control lever 19
is turned.
[0043] More specifically, when the bucket control lever 19 is
turned toward the D direction, the selector valve 50 moves to the D
position (DOWN position). When the bucket control lever 19 is
turned toward the U direction, the selector valve 50 moves to the U
position (UP position). The bucket control lever 19 is always in
the N position (neutral) by coil springs (not illustrated) whenever
it is not operated. Operation buttons B1, B2 are installed on the
front side of the bucket control lever 19. Furthermore, operation
buttons B1, B2 project from the front side of the bucket control
lever 19. An operation button B3 is installed on the upper side of
the bucket control lever 19. Furthermore, the operation button B3
projects from the upper side of the bucket control lever 19. Each
operation button B1, B2, B3 is made of resin and is a column with a
dome-like tip. The back of the operation buttons B1, B2, B3 are
flat. The actuator of each switch (the switch is a push-plunger
type limit switch with the actuator) touches the back of the
operation buttons B1, B2 and B3, respectively.
[0044] Three switches of the operation buttons B1, B2, B3 are
respectively connected to the controller (described later). The
solenoid valve SL is moved to the position U when the operation
button B1 is pressed. On the other hand, the solenoid valve SL is
moved to the position D when the operation button B2 is pressed.
The automatic bucket level control for the bucket 26 starts when
the operation button (an angle control switch) B3 is pressed (and
then the switch is ON). The automatic bucket level control for the
bucket 26 ends when the operation button (an angle control switch)
B3 is pressed again (and then the switch is OFF).
[0045] The boom control lever 20 is to operate the lift cylinders
23. The boom control lever 20 consists of a grip 20a, a rod 20b and
a protection part 20c. The grip 20a is made of resin and shaped by
an injection molder. The lower part of the rod 20b is held inside
the right fender F. The protection part 20c covers the gap between
the rod 20b and the fender F in order to prevent dust from entering
the fender F. The protection part 20c is made of a flexible
material to enable it to follow the movement of the rod 20b. The
boom control lever 20 is connected to a selector valve 51. The
selector valve 51 changes position when the boom control lever 20
is turned.
[0046] More specifically, when the boom control lever 20 is turned
toward the D direction, the selector valve 51 moves to the D
position (DOWN position). When the boom control lever 20 is turned
toward the U direction, the selector valve 51 moves to the U
position (UP position). The boom control lever 20 is always in the
N position (neutral) by coil springs (not illustrated) whenever it
is not operated.
[0047] The hydraulic circuit is connected to the hydraulic fluid
tank (not illustrated). The hydraulic fluid can move with a
constant pressure between the hydraulic fluid tank and the dump
cylinders 24 when the bucket control lever 19 is in operation. The
hydraulic fluid can move with a constant pressure between the
hydraulic fluid tank and the boom cylinders 23 when the boom
control lever 20 is in operation. The dump cylinders 24 expand when
the bucket control lever 19 is turned toward the D direction. On
the other hand, the dump cylinders 24 shrink when the bucket
control lever 19 is turned toward the U direction. The lift
cylinders 23 shrink when the boom control lever 20 is turned toward
the D direction. On the other hand, the lift cylinders 23 expand
when the boom control lever 20 is turned toward the U
direction.
[0048] The procedure for operating the front loader 16 by use of
the bucket control lever 19 and the boom control lever 20 is
described as follows: In order to move the booms 21 upward, turn
the boom control lever 20 toward the operator's side (the U
direction). The selector valve 51 moves toward the U position.
Then, the hydraulic circuit of the lift cylinders 23 is opened to
expand the lift cylinders 23. In order to stop moving the booms 21
upward, release your hand from the boom control lever 20. The boom
control lever 20 returns to the N position and the selector valve
51 moves toward the N position to close the hydraulic circuit of
the lift cylinders 23.
[0049] In order to move the booms 21 downward, turn the boom
control lever 20 frontward (the D direction). The selector valve 51
moves toward the D direction. Then, the hydraulic circuit of the
lift cylinders 23 is opened to shrink the lift cylinders 23. In
order to stop moving the booms 21 downward, release your hand from
the boom control lever 20. The boom control lever 20 returns to the
N position, and the selector valve 51 moves toward the N position
for closing the hydraulic circuit of the lift cylinders 23.
[0050] In order to move the bucket 26 upward, turn the bucket
control lever 19 backward (the U direction). The selector valve 50
moves toward the U direction. Then, the hydraulic circuit of the
dump cylinders 24 is opened to shrink the dump cylinders 24. In
order to stop moving the bucket 26 upward, release your hand from
the bucket control lever 19. The bucket control lever 19 returns to
the N position, and the selector valve 50 moves toward the N
position for closing the hydraulic circuit of the dump cylinders
24.
[0051] In order to move the bucket 26 downward, turn the bucket
control lever 19 frontward (the D direction). The selector valve 50
moves toward the D direction. Then, the hydraulic circuit of the
dump cylinders 24 is opened to expand the dump cylinders 24. In
order to stop moving the bucket 26 downward, release your hand from
the bucket control lever 19. The bucket control lever 19 returns to
the N position and the selector valve 50 moves toward the N
position to close the hydraulic circuit of the dump cylinders
24.
[0052] The bucket 26 can also be operated upwardly or downwardly by
the operation buttons B1 and B2, respectively. The solenoid valve
SL moves toward the U position when the operation button B1 is
pressed while the bucket control lever 19 is in the N position. The
solenoid valve SL moves back to the N position when your hand is
released from the operation button B1. The solenoid valve SL moves
toward the D position when the operation button B2 is pressed while
the bucket control lever 19 is in the N position. The solenoid
valve SL moves back to the N position when your hand is released
from the operation button B2. The controller (described later) is
in between the operation buttons B1, B2 and the solenoid valve SL.
The solenoid valve SL is moved by the controller.
[0053] FIG. 5 shows the main block diagram of this embodiment (the
engine is described as "E"). The controller (a control part) CT,
which is inside a dashboard in front of the driver's seat 17, is
connected with the operation buttons B1, B2, B3. The controller CT
is also connected with the tilt sensor TS. Furthermore, the
controller CT is connected to the solenoid valve SL and operates
it.
[0054] The controller CT is able to conduct the automatic bucket
level control process for the bucket 26, which keeps the bucket 26
level. FIG. 6 shows the automatic bucket level control program flow
chart for the controller CT. The controller CT periodically senses
if the tilt sensor TS is working (STEP1). If the tilt sensor TS is
not working, the controller CT gives an alarm on the display, which
is installed in front of the driver's seat 17 (STEP2). If the tilt
sensor TS is working, the controller CT program proceeds to STEP3
and the controller CT senses if the operation button (the automatic
level control button) B3 is ON. If the operation button B3 is OFF,
then, the controller CT program proceeds to STEP4 and the
controller CT ends the automatic level control program (or the
controller CT does not start the program). If the operation button
B3 is ON, then the controller CT program proceeds to STEP5 and the
controller CT starts the automatic level control program.
[0055] Furthermore, at STEP6, the controller CT periodically senses
if the bucket 26 is level via the tilt sensor (an angle sensing
means) TS. If the bucket 26 is level, the controller CT program
goes back to STEP3. If the bucket 26 is not level, the controller
CT program goes to STEP7 and the controller CT senses if the upper
edge 26su of the bucket 26 is turning more than the level (the
horizontal) or, in other words, the upper edge 26su is turning
backward (toward the driver' seat 17) more than the level. If the
upper edge 26su is turning more than the level, the controller CT
moves the solenoid valve SL toward the DOWN position to expand the
dump cylinder 24 (STEPS). If the upper edge 26su is not turning
more than the level, the controller CT program proceeds to STEPS
and the controller CT senses if the upper edge 26su is turning less
than the level. If the upper edge 26su is not turning less than the
level, the controller CT program goes back to STEP1. If the upper
edge 26su is turning less than the level (the horizontal), the
controller CT moves the solenoid valve SL toward the UP position
for shrinking the dump cylinder 24 (STEP10).
[0056] The automatic level control precedes the bucket manual
operation with the operation buttons B1, B2.
[0057] The automatic level control program in this embodiment can
be applied not only to the horizontal control of the bucket but
also angle control of the bucket in any plane--it is called an
automatic angle control program. In such cases, an angle set dial,
which is connected to the operation button B3, should be set on the
bucket control lever 19 in order to automatically control the
bucket angle with respect to the level. In addition, the target
angle of the bucket 26 may be input through a touch screen
display.
Further Embodiment 1
[0058] FIG. 7 shows a further embodiment of this invention. In this
embodiment, a tilt sensor TS1 is installed on the rear part 26bk of
the bucket 26. Other components of the tractor 10 are not described
as they are the same as the previous embodiment.
[0059] The bucket 26 is made of metal. It is comprised of a bottom
part 26bt, a pair of side parts 26s, a rear part 26bk, a back part
26b and a top part 26u. The side parts 26s are vertically installed
at both ends of the bottom part 26bt. The rear part 26bk is
connected to the side parts 26s at both of its ends. The back part
26b is connected to the rear part 26bk and is also connected to the
pair of side parts 26s at both of its ends. A pair of stays 26A is
put on the rear part 26b. A hook bar 26B is fixed to the pair of
stays 26A at both of its ends. A tilt sensor (an angle detection
means) TS1 is equipped underneath the hook bar 26B. Alternatively,
the tilt sensor TS1 may be equipped on the top part 26u or the back
part. The tilt sensor TS1 is to sense the angle position of the
bucket 26 from the horizontal; however, the tilt sensor TS1 may
sense the angular position of the bucket 26 from the vertical,
instead. The tilt sensor TS1 is connected to a controller CT with a
harness.
[0060] The automatic bucket level control process, which gives an
automatic level control for the bucket 26, is the same as the
previous embodiment shown in FIG. 6. If the tilt sensor is
installed on the side part 26s, as described in the previous
embodiment, the tilt sensor might be broken by sand or rocks when
the tractor 10 digs. However, if the tilt sensor TS1 is installed
on the rear part 26bk (or the upper part 26u, the back part 26b),
the risk of the tilt sensor TS1 being broken unexpectedly as just
described can be reduced.
Further Embodiment 2
[0061] Another embodiment of this invention is shown in FIG. 8 to
FIG. 11. In this embodiment, a boom-bucket control lever JS is
introduced instead of the bucket control lever 19 and the boom
control lever 20. In this embodiment, the boom-bucket control lever
JS has two functions: a bucket control function and a boom control
function. The boom-bucket control lever JS is positioned on the
fender F. Other components of the tractor 10 are the same as the
first embodiment. When the boom-bucket control lever JS is turned
frontward or backward (BD-BU direction in FIG. 9), the selector
valve 51 is operated and the booms 21 are turned. On the other
hand, when the boom-bucket control lever JS is turned left-sideward
or right-sideward (AU-AD direction in FIG. 9), the selector valve
50 is operated and the bucket 26 is turned. Operation buttons B1,
B2 are installed on the front side of the boom-bucket control lever
JS. Furthermore, operation buttons B1, B2 project from the front
side of the boom-bucket control lever JS. An operation button B3 is
installed on the upper side of the boom-bucket control lever JS.
Furthermore, the operation button B3 projects from the upper side
of the boom-bucket control lever JS.
[0062] The hydraulic circuit is connected to the hydraulic fluid
tank (not illustrated). The hydraulic fluid can move with a
constant pressure between the hydraulic fluid tank and the dump
cylinders 24 when the boom-bucket control lever JS is in operation.
The hydraulic fluid can move with a constant pressure between the
hydraulic fluid tank and the boom cylinders 23 when the boom-bucket
control lever JS is in operation. The dump cylinders 24 expand when
the boom-bucket control lever JS is turned toward the AD direction.
On the other hand, the dump cylinders 24 shrink when the
boom-bucket control lever JS is turned toward the AU direction. The
lift cylinders 23 shrink when the boom-bucket control lever JS is
turned toward the BD direction. On the other hand, the lift
cylinders 23 expand when the boom-bucket control lever JS is turned
toward the BU direction.
[0063] The procedure for operating the front loader 16 by use of
the boom-bucket control lever JS is described as follows: in order
to move the booms 21 upward, turn the boom-bucket control lever JS
backward (the BU direction). The selector valve 51 moves toward the
BU position. Then, the hydraulic circuit of the lift cylinders 23
is opened to expand the lift cylinders 23. In order to stop moving
the booms 21 upward, release your hand from the boom-bucket control
lever JS. The boom-bucket control lever JS returns to the N
position and the selector valve 51 moves toward the N position to
close the hydraulic circuit of the lift cylinders 23.
[0064] In order to move the booms 21 downward, turn the boom-bucket
control lever JS forward (the BD direction). The selector valve 51
moves toward the BD direction. Then, the hydraulic circuit of the
lift cylinders 23 is opened to shrink the lift cylinders 23. In
order to stop moving the booms 21 downward, release your hand from
the boom-bucket control lever JS. The boom-bucket control lever JS
returns to the N position, and the selector valve 51 moves toward
the N position for closing the hydraulic circuit of the lift
cylinders 23.
[0065] In order to move the bucket 26 upward, turn the boom-bucket
control lever JS left-sideward (the AU direction). The selector
valve 50 moves toward the AU direction. Then, the hydraulic circuit
of the dump cylinders 24 is opened to shrink the dump cylinders 24.
In order to stop moving the bucket 26 upward, release your hand
from the boom-bucket control lever JS. The boom-bucket control
lever JS returns to the N position, and the selector valve 50 moves
toward the N position for closing the hydraulic circuit of the dump
cylinders 24.
[0066] In order to move the bucket 26 downward, turn the
boom-bucket control lever JS right-sideward (the AD direction). The
selector valve 50 moves toward the AD direction. Then, the
hydraulic circuit of the dump cylinders 24 is opened to expand the
dump cylinders 24. In order to stop moving the bucket 26 downward,
release your hand from the boom-bucket control lever JS. The
boom-bucket control lever JS returns to the N position and the
selector valve 50 moves toward the N position to close the
hydraulic circuit of the dump cylinders 24.
[0067] As with the previous embodiments, the bucket 26 can also be
operated upwardly or downwardly by the operation buttons B1 and B2,
respectively. The solenoid valve SL moves toward the U position
when the operation button B1 is pressed while the boom-bucket
control lever JS is in the N position. The solenoid valve SL moves
back to the N position when your hand is released from the
operation button B1. The solenoid valve SL moves toward the D
position when the operation button B2 is pressed while the
boom-bucket control lever JS is in the N position. The solenoid
valve SL moves back to the N position when your hand is released
from the operation button B2. The controller CT is in between the
operation buttons B1, B2 and the solenoid valve SL. The solenoid
valve SL is moved by the controller CT. The automatic bucket level
control program flow chart shown in FIG. 6 applies to this
embodiment.
* * * * *