U.S. patent application number 11/375823 was filed with the patent office on 2006-10-26 for hydraulic lift assist for tractor towed earth moving apparatus.
Invention is credited to Mark R. Miskin.
Application Number | 20060237203 11/375823 |
Document ID | / |
Family ID | 36581961 |
Filed Date | 2006-10-26 |
United States Patent
Application |
20060237203 |
Kind Code |
A1 |
Miskin; Mark R. |
October 26, 2006 |
Hydraulic lift assist for tractor towed earth moving apparatus
Abstract
The present invention includes hydraulic systems designed to
allow the selection of a source of pressurized hydraulic fluid to
lift a load. In one embodiment, a hydraulic system in accordance
with the present invention comprises a hydraulic accumulator that
may be selected as a source of pressurized hydraulic fluid to lift
a load. Such a hydraulic system may or may not be part of a cushion
ride system. The present invention also includes methods for
selecting a source of pressurized hydraulic fluid to lift a load
and earth moving or ground leveling apparatus that allow the
selection of a source of pressurized hydraulic fluid to lift a
load.
Inventors: |
Miskin; Mark R.; (Alta,
WY) |
Correspondence
Address: |
MORRISS O'BRYANT COMPAGNI, P.C.
136 SOUTH MAIN STREET
SUITE 700
SALT LAKE CITY
UT
84101
US
|
Family ID: |
36581961 |
Appl. No.: |
11/375823 |
Filed: |
March 15, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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60661703 |
Mar 15, 2005 |
|
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Current U.S.
Class: |
172/799.5 |
Current CPC
Class: |
E02F 3/6454 20130101;
F15B 2211/324 20130101; F15B 2211/625 20130101; F15B 2211/6336
20130101; E02F 3/651 20130101; F15B 1/024 20130101; E02F 3/6481
20130101; F15B 2211/3138 20130101; E02F 9/2217 20130101; F15B
2211/327 20130101; F15B 2211/3056 20130101; F15B 1/021 20130101;
F15B 2211/205 20130101; F15B 2211/212 20130101; E02F 3/652
20130101 |
Class at
Publication: |
172/799.5 |
International
Class: |
E02F 3/76 20060101
E02F003/76 |
Claims
1. A hydraulic system for lifting a load, comprising: a hydraulic
accumulator; a hydraulic cylinder situated to lift a load upon
actuation; and one or more valves controlling the entry and exit of
hydraulic fluid from the hydraulic accumulator, wherein at least
one of the one or more valves is operatively disposed between the
hydraulic accumulator and the hydraulic cylinder situated to lift a
load and allowing for the non-selection of the accumulator as a
source of hydraulic fluid to actuate the hydraulic cylinder
situated to lift the load.
2. The hydraulic system of claim 1, wherein the at least one of the
one or more valves is an operator controlled valve.
3. The hydraulic system of claim 1, wherein the at least one of the
one or more valves is controlled by a sensor.
4. The hydraulic system of claim 3, wherein the sensor is selected
from the group consisting of a sensor for indicating the movement
of the hydraulic cylinder situated to lift a load, a sensor for
sensing the speed of a vehicle on which the apparatus is mounted, a
sensor for sensing which gear a transmission of a prime mover is
currently engaged, a sensor for sensing the engine speed of a prime
mover, and a sensor for sensing the flow of hydraulic fluid to or
from the hydraulic cylinder situated to lift a load.
5. The hydraulic system of claim 1, further comprising a cushion
ride system.
6. The hydraulic system of claim 5, wherein the wherein the cushion
ride system comprises a second hydraulic accumulator.
7. The hydraulic system of claim 1, where the load comprises a
bucket of an earth moving apparatus.
8. The hydraulic system of claim 1, further comprising a source
generating pressurizing hydraulic fluid in operative connection to
the accumulator, the source located on a separate prime mover.
9. An earth moving apparatus comprising: a hydraulic accumulator; a
hydraulic cylinder situated to lift a frame of an earth moving
apparatus, the hydraulic cylinder operatively connected to the
hydraulic accumulator; and a valve disposed between the hydraulic
accumulator and the hydraulic cylinder for controlling the flow of
hydraulic fluid from the hydraulic accumulator to the hydraulic
cylinder situated to lift a frame of the earth moving
apparatus.
10. The earth moving apparatus of claim 9, wherein the earth moving
apparatus comprises an earth moving scraper.
11. The earth moving apparatus of claim 9, wherein the earth moving
apparatus further comprises structures for operatively connecting
to a source of pressurizing hydraulic fluid located on a separate
prime mover.
12. The earth moving apparatus of claim 9, wherein the valve is an
operator controlled valve.
13. The earth moving apparatus of claim 9, further comprising a
sensor associated with the hydraulic system of the earth moving
apparatus.
14. The earth moving apparatus of claim 13, wherein the valve is
controlled by the sensor.
15. The earth moving apparatus of claim 14, wherein the sensor is
selected from the group consisting of a sensor for indicating the
movement of the hydraulic cylinder situated to lift a scraper
frame, a sensor for sensing the speed of the earth moving
apparatus, a sensor for sensing which gear a transmission of a
prime mover is currently engaged, a sensor for sensing the engine
speed of a prime mover, and a sensor for sensing the flow of
hydraulic fluid to or from the hydraulic cylinder situated to lift
a frame of the earth moving apparatus.
16. The earth moving apparatus of claim 9, further comprising a
cushion ride system.
17. The earth moving apparatus of claim 16, wherein the wherein the
cushion ride system comprises a second hydraulic accumulator.
18. An improved earth moving or ground leveling apparatus having a
frame with opposing sides, at least two ground engaging wheels
supporting the frame, and a bucket with a floor and a pair of
sidewalls, the improvement comprising: a hydraulic accumulator; a
hydraulic cylinder situated to lift the bucket; and one or more
valves controlling the entry and exit of hydraulic fluid from the
hydraulic accumulator, wherein at least one of the one or more
valves is operatively disposed between the hydraulic accumulator
and the hydraulic cylinder situated to lift the bucket and allowing
for the non-selection of the accumulator as a source of hydraulic
fluid to actuate the hydraulic cylinder situated to lift the
bucket.
19. The improved earth moving or ground leveling apparatus of claim
18, wherein the at least one of the one or more valves is an
operator controlled valve.
20. The improved earth moving or ground leveling apparatus of claim
18, wherein the at least one of the one or more valves is
controlled by a sensor.
21. The improved earth moving or ground leveling apparatus of claim
20, wherein the sensor is selected from the group consisting of a
sensor for indicating the movement of the hydraulic cylinder
situated to lift a scraper frame, a sensor for sensing the speed of
the earth moving apparatus, a sensor for sensing which gear a
transmission of a prime mover is currently engaged, a sensor for
sensing the engine speed of a prime mover, and a sensor for sensing
the flow of hydraulic fluid to or from a hydraulic cylinder of the
earth moving or ground leveling apparatus.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of U.S. Provisional
Application No. 60/661,703, filed Mar. 15, 2005, which is
incorporated herein by reference in its entirety.
TECHNICAL FIELD
[0002] The present invention relates generally to hydraulic systems
for lifting a load. More specifically, the present invention
relates to hydraulic systems that allow the selection of a
secondary source of hydraulic power to lift a load.
BACKGROUND
[0003] Certain kinds of earth moving equipment use a single power
source for multiple purposes. For instance, a tractor may use its
internal combustion engine to not only provide locomotion, but to
also operate a high pressure hydraulic pump. While the tractor
engine is typically able to provide sufficient horsepower for all
needs, there may arise situations where the tractor engine is under
powered.
[0004] One example might include a tractor being used to pull an
earth moving apparatus. As the tractor pulls the earth moving
apparatus, it fills with earth thereby increasing the resistance to
the tractor pull. In order to compensate for this increased
resistance, the operator of the tractor may gradually lift the
frame of the earth moving apparatus, and, thereby the cutting
blade, as the apparatus fills with earth. This lifting of the
cutting blade, using the tractor's hydraulic system, decreases the
resistance to the tractor's pull as the blade cuts less deeply into
the earth. However, because the earthmoving apparatus' hydraulic
system is powered by the tractor's engine, the horsepower of the
engine must now be split between the simultaneous pulling of the
earth moving apparatus and the lifting of the cutting blade. If the
tractor is in a heavy pull, operating the hydraulics to lift the
cutting blade may put enough extra drag on the engine to cause it
to stall.
[0005] Many hydraulic systems for lifting loads, such as an earth
moving apparatus frame and/or cutting blade, are known. Such
hydraulic systems typically use hydraulic pressure to actuate a
hydraulic cylinder in such a way that a load is lifted. However, if
the primary source of pressurized hydraulic fluid fails or is
unable to provide sufficient hydraulic pressure, the system will be
unable to lift the load.
[0006] A number of systems exist to provide hydraulic pressure
given the absence, or failure, of a primary source of pressurized
hydraulic fluid. Representative examples include, without
limitation, the hydraulic systems disclosed in U.S. Pat. Nos.
5,313,795, 5,090,495, 3,965,587, 4,360,187, 5,037,368, 5,516,070,
5,806,838, 3,945,685, and 3,945,691, the disclosures of each which
are hereby incorporated by reference. These systems typically use a
hydraulic accumulator to store hydraulic pressure to be used in the
absence or failure of another power source. Systems of this type
are typically constantly engaged to the active hydraulic system
with the accumulator being `inline` between the sources of
pressurized hydraulic fluid and the ultimate use. Such systems can
be said to be `constantly engaged` as the operator of the system
has no means of selecting when the pressure stored in the
accumulator is not to be used, i.e. no means of disconnecting the
accumulator from the hydraulic system. As such, the constant
engagement of such systems do not allow the operator or designer of
the hydraulic system to select whether the primary source of
pressurized hydraulic fluid or the reserve hydraulic pressure in
the accumulator is to be used for a given purpose. The reserve
pressure is always available regardless of the operator's wishes.
However, the hydraulic systems typical of earth moving machinery
are designed so as to not be under significant pressure unless they
are being used. Thus, a `constantly engaged` accumulator would
provide hydraulic pressure to the system every time the primary
source is not in use, even when the operator desires that there be
relatively little hydraulic pressure in the system.
[0007] Other systems for selectively engaging an accumulator with a
hydraulic system only engage when the hydraulic pressure in the
system falls below a predetermined level. Representative examples
include, without limitation, the hydraulic systems disclosed in
U.S. Pat. Nos. 4,736,991, and 4,792,192, the disclosures of each
which are hereby incorporated by reference. However, such selective
engagement systems are of little aid in selectively raising an
earth moving apparatus frame, bucket, or cutting blade. This is
because the hydraulic systems typical of earth moving machinery are
not under significant pressure unless they are being used. Thus, an
accumulator under a pressure sensitive control provides hydraulic
pressure to the system every time the primary source is not in use,
precisely when the operator desires that there be relatively little
hydraulic pressure in the system.
[0008] Lastly, accumulator systems that engage when a certain back
pressure has been reached are also known. A representative example
includes, without limitation, the hydraulic system disclosed in
U.S. Pat. No. 2,846,187, the disclosure of which is hereby
incorporated by reference. In such a system, the hydraulic pressure
in an accumulator is released into a hydraulic system when the
pressure in the hydraulic system rises to a predetermined level.
Such systems increase the hydraulic flow, allowing the hydraulic
system to actuate more quickly, but would be of little use where
the primary source of hydraulic power is unable to provide that
predetermined hydraulic pressure. Further, such systems do not
allow the operator or designer of the hydraulic system to select
whether the primary source of pressurized hydraulic fluid or the
reserve hydraulic pressure in the accumulator is used.
[0009] As such, an improved hydraulic system that allows the
selective introduction of a reserve source of pressurized hydraulic
fluid to lift a load would be an improvement in the art.
SUMMARY
[0010] The present invention includes hydraulic systems designed to
allow the selection of a source of pressurized hydraulic fluid to
lift a load. In one illustrative embodiment, a hydraulic system in
accordance with the present invention comprises a hydraulic
accumulator that may be selected as a source of pressurized
hydraulic fluid to lift a load. Such a hydraulic system may or may
not be part of a cushion ride system.
[0011] The present invention also includes methods for selecting a
source of pressurized hydraulic fluid to lift a load. In one
illustrative embodiment, a source of pressurized hydraulic fluid is
used to charge an accumulator. The hydraulic pressure in the
accumulator is then used to lift the load when selected to do
so.
[0012] A further illustrative embodiment of the present invention
includes a hydraulic system comprising a hydraulic accumulator that
may be selected as a source of pressurized hydraulic fluid to lift
a load into earth moving or ground leveling apparatus. The load
lifted in the earth moving apparatus may be the earth moving or
ground leveling apparatus frame, wheels, apron, cutting blade or
other portion of the earth moving or ground leveling apparatus or
its cargo. Such a hydraulic system may or may not be part of a
cushion ride system incorporated into the earth moving or ground
leveling apparatus.
DESCRIPTION OF THE DRAWINGS
[0013] It will be appreciated by those of ordinary skill in the art
that the elements depicted in the various drawings are not to
scale, but are for illustrative purposes only. The nature of the
present invention, as well as other embodiments of the present
invention may be more clearly understood by reference to the
following detailed description of the invention, to the appended
claims, and to the several drawings attached hereto.
[0014] FIG. 1 is a schematic diagram of an illustrative embodiment
of a hydraulic system for selectively regulating the flow of a
hydraulic fluid into and out of a hydraulic accumulator.
[0015] FIG. 2 is a schematic diagram of a second illustrative
embodiment of a hydraulic system for selectively regulating the
flow of hydraulic fluid between a source of pressurized hydraulic
fluid, a hydraulic accumulator, a hydraulic cylinder, and a cushion
ride system.
[0016] FIG. 3 illustrates a further embodiment of an earth moving
apparatus on to which the hydraulic system of the present invention
may be incorporated.
DETAILED DESCRIPTION
[0017] It will be appreciated that the embodiments described
herein, while illustrative, are not intended to so limit the
invention or the scope of the appended claims. Those of ordinary
skill in the art will understand that various combinations or
modifications of the embodiments presented herein maybe made
without departing from the scope of the present invention.
[0018] Referring now to drawing FIG. 1, there is illustrated a
schematic view of a hydraulic system in accordance with the present
invention generally at 100. As illustrated, the hydraulic system
100 comprises a source of pressurized hydraulic fluid generally at
102. The source of pressurized hydraulic fluid generally at 102
includes, as illustrated, a hydraulic pump 104, a reservoir of
hydraulic fluid 106, a selector valve 108, and an engine 109 for
driving hydraulic pump 104. A non-limiting example of a source of
pressurized hydraulic fluid generally at 102 would be the engine
and high pressure hydraulic system present on a prime mover.
Examples of prime movers include, but are not limited to, tractors,
trucks, and various other self-propelled vehicles. Hydraulic system
100 further comprises hydraulic lines 110a and 110b, which may be
used to carry hydraulic fluid to and from hydraulic cylinders 112a
and 112b. Branching from hydraulic line 110a is a lift assist
system generally at 114. The lift assist system generally at 114
includes an accumulator 116, a check valve 118, a valve 120, and a
check valve 122. As shown, the directional force of the load on
hydraulic cylinder 112a is as indicated by arrow 124.
[0019] Although not illustrated, the hydraulic system 100 may also
be used to operate multiple hydraulic cylinders which can be single
or double acting. Such additional cylinders may include, for
example, but are not limited to, cylinders for raising or lowering
a scraper bucket, opening or closing a scraper apron, operating a
load ejector, operating a brake system, or providing pilot pressure
for other hydraulic valves. These other operative hydraulic systems
are as illustrated and disclosed in U.S. Pat. Nos. 4,383,380,
4,388,769, 4,398,363, 4,553,608, and 6,347,670 to Miskin which are
incorporated herein by reference.
[0020] During normal operation, valve 120 remains closed. As
hydraulic cylinders 112a and 112b are actuated during normal
operation, hydraulic oil under pressure will pass through check
valve 118 to be stored in accumulator 116. If the operator desires,
or if a certain predetermined condition or conditions are sensed,
valve 120 may be caused to open allowing the stored hydraulic oil
under pressured to pass through valve 120 and check valve 122 and
into hydraulic line 110a. If the stored hydraulic pressure in
accumulator 116 is sufficient, hydraulic cylinders 112a and 112b
will actuate to lift the load. When actuating the hydraulic
cylinder causes the lifting of a load comprising the frame of an
earth moving apparatus, bucket, and/or cutting blade, the demands
on engine 109 may be thereby reduced, allowing the source of
pressurized hydraulic fluid generally at 102 to further lift the
load without assistance of the hydraulic pressure stored in the
accumulator.
[0021] It will be appreciated by one of skill in the art that
various types of valve 120 may be used. In one exemplary
embodiment, valve 120 may comprise an electrically-controlled,
solenoid-type valve that may be controlled by a control switch (not
shown) that may be located in the cab of the prime mover used to
pull the apparatus to which hydraulic system 100 is mounted, or, if
the apparatus on which hydraulic system 100 is self-propelled, the
control switch (not shown) may be located in the control area of
the self-propelled apparatus. In other embodiments, valve 120 may
be any type of hydraulic valve and controlled in any manner known
in the art, such as by mechanical systems and the like. Other types
of valves that may be used with hydraulic system 100 of the present
invention include, without limitation, sandwich valves, hydraulic
control valves, electro-hydraulic valves, remote control valves,
mobile valves, directional control valves, check valves, glove
valves, gate valves, and other types of manual control valves.
Types of control systems that may be used to control valve 120 of
the present invention include, without limitation, pressure
controlled systems, pneumatic systems, vacuum systems,
electronically controlled systems, automatically controlled
systems, manually controlled systems, remote control systems, and
mechanically linked systems.
[0022] As would be apparent to one of skill in the art, a load
comprises the force of gravity acting on a particular mass so as to
drive the actuation of a piston rod of a hydraulic cylinder. In one
exemplary embodiment, the load may be the weight of the frame of an
earth moving apparatus. The lifting of a load comprises the
actuation of a hydraulic cylinder causing a load to move against
the force of gravity.
[0023] Referring now to drawing FIG. 2, there is illustrated a
schematic view of a hydraulic system in accordance with the present
invention generally at 200. As illustrated, the hydraulic system
200 includes a cushion ride system generally at 210 in place of
check valve 118. When actuated, the cushion ride system utilizes
the accumulator 116 as a shock absorber when the hydraulic system
200 is mounted on a vehicle such as an earth moving or ground
leveling apparatus. Examples of using an accumulator as a shock
absorber can be found in U.S. Pat. Nos. 6,382,326 and 6,749,035,
both of which are incorporated herein by reference. As illustrated,
cushion ride system generally at 210 may comprise check valves 212
and 214, valves 216 and 220, and restrictor 218. Also depicted is
valve 222. During normal operation, valve 222 remains open.
However, if it desired to charge accumulator 116 without actuating
hydraulic cylinders 112a and 112b, valve 222 may be closed, thereby
diverting the flow of pressurized hydraulic away from hydraulic
cylinders 112a and 112b.
[0024] Hydraulic system 200 further includes sensor 224 for sensing
the flow of hydraulic fluid in hydraulic line 110a. As shown,
sensor 224 may be operatively connected to valves 120 and 220 so as
to control the position of valves 120 and 220 in response to
predetermined sensor inputs. It will be appreciated by one of skill
in the art that the position and type of sensor 224 described is
merely exemplary and that any number of sensors inputs may be used
to determine when valves 120 and 220 are opened. Such sensors or
inputs include, but are not limited to, operator decision, a system
for sensing a failure of movement of hydraulic cylinders 112a and
112b when selector valve 108 is actuated so as to lift the load, a
speed sensor for sensing the speed of the prime mover, a system for
sensing the engine speed of a prime mover, a system for sensing
which gear the transmission of the prime mover is currently in, or
a system for sensing a lack of hydraulic fluid flow in hydraulic
line 110a when selector valve 108 is actuated so as to lift the
load.
[0025] At the beginning of normal operation, valves 120 and 220 are
opened and valve 222 closed so that hydraulic fluid under pressure
from the source of pressurized hydraulic fluid generally at 102 can
pass through valves 216 and 220 as well as check valve 212 and/or
restrictor 218 to be stored in accumulator 116. Once the
accumulator 116 is charged, valves 120 and 220 are closed and valve
222 is opened. If, at any time, the stored pressurized hydraulic
fluid in accumulator 116 is selected to actuate hydraulic cylinders
112a and 112b, valves 120 and 220 will be opened and the hydraulic
fluid will pass through restrictor 218 as well as valves 120 and
220 and into hydraulic line 110a. If the stored hydraulic pressure
in hydraulic accumulator 116 is sufficient, hydraulic cylinders
112a and 112b will be actuated to lift the load. To recharge
accumulator 116, valve 222 may again be closed while valves 120 and
220 remain open to allow hydraulic fluid under pressure from the
source of pressurized hydraulic fluid generally at 102 to pass into
the accumulator. In the alternative, the accumulator may be
recharged when piston rod 318 reaches its maximum extension while
valves 120 and 220 remain open. To operate the cushion ride system,
the operator interrupts the connection between hydraulic lines 110a
and 110b and hydraulic pump 114 using selector valve 108. Valves
216 and 220 are then opened. Any forces on hydraulic cylinders 112a
and 112b are then dampened by the entry and release of hydraulic
fluid from accumulator 116.
[0026] Referring now to drawing FIG. 3, which is a side view of an
earth moving apparatus generally at 300. Scrapers and earthmoving
apparatuses of the general type to which earth moving apparatus 300
relate are generally known. Representative examples of earthmoving
apparatuses include, without limitation, the scrapers disclosed in
U.S. Pat. Nos. 4,383,380, 4,388,769, 4,398,363, 4,553,608, and
6,347,670 to Miskin, the disclosures of which are herein
incorporated by reference. A typical earth moving apparatus
includes a bucket for holding earth. The bucket includes a floor, a
rear wall, two upstanding opposing side walls, an open front, and
an open top. An apron, or gate, is located opposite the rear wall
of the bucket and can swing closed to hold the soil in the bucket
during transport. In a scraper device, a blade is located adjacent
the front edge of the floor of the bucket and cuts the earth to a
predetermined depth as the earth moving apparatus is moved forward
over the earth's surface. The soil cut from the earth by the blade
is collected in the bucket. When the bucket is full of soil, the
earth moving apparatus is transported to another location where the
soil is deposited. Other examples of earth moving apparatuses
having a bucket include, but are not limited to, dump trucks,
backhoes, and front end loaders.
[0027] More specifically, the depicted exemplary earth moving
apparatus generally at 300 includes a frame 302, a cutting blade
304, a bucket 306, an apron 308 a tongue 310 and at least two
ground engaging wheels 312. An actuator, such as hydraulic cylinder
112a has a first end 314 and a second end 316. When a piston rod
318 of the hydraulic cylinder 112a is extended (as shown), the
frame 302 is effectively raised. The imposed weight of frame 302
thus applies pressure upon the piston rod of hydraulic cylinder
112a. According the present invention, the pressure stored in
accumulator 116 (not shown) may be used extend piston rod 318 of
the hydraulic cylinder to effectively raise the frame 302 and
therefore the bucket 306 and the cutting blade 304.
[0028] When beginning an earth scraping operation using an earth
moving apparatus such as the an earth moving apparatus generally at
300, the operator first lifts the frame 302 by supplying hydraulic
pressure to hydraulic cylinders 112a and 112b through hydraulic
line 10a by the selection of the proper setting of selector valve
108. The charging of the hydraulic accumulator 116 would occur
automatically when the piston rod 318 is fully extended, if the
hydraulic system is equipped with a check valve 118, or, if the
earth moving apparatus 300 is equipped with a cushion ride system,
such as the cushion ride system generally at 210, the accumulator
can be charged when piston rod 318 reaches its maximum extension
and valves 120 and 220 are opened or when valve 222 is closed and
valves 120 and 220 are opened.
[0029] During normal operation, as the bucket 306 fills with earth,
the resistance to the pull of the prime mover will increase. To
mitigate this increased resistance, the operator or a sensor input
may select to raise the frame 302, and thereby bucket 306 and
cutting blade 304. However, if the tractor is in a heavy pull,
engine 109 may not have enough power to both pull earth moving
apparatus 300 and provide sufficient hydraulic pressure via
hydraulic pump 104 to lift frame 302, and thereby bucket 306 and
cutting blade 304. To provide sufficient hydraulic pressure, the
operator or a sensor input from as sensor such as sensor 224 causes
valves 120 and 220 to open releasing the hydraulic pressure stored
in hydraulic accumulator 116, through valves 120 and 220, and into
hydraulic line 110a. If the hydraulic pressure stored in hydraulic
accumulator is sufficient, piston rod 318 of hydraulic cylinder
112a will be extended, raising the frame 302, and thereby bucket
306 and cutting blade 304. The resistance to the pull of the prime
mover will be thereby decreased allowing the engine 109 to provide
enough power to both pull earth moving apparatus 300 and provide
sufficient further hydraulic pressure via hydraulic pump 104 to
lift frame 302, and thereby bucket 306 and cutting blade 304. If
the hydraulic system is equipped with a check valve 118 the
accumulator 116 will be recharged when piston rod 318 reaches its
maximum extension, or, if the earth moving apparatus 300 is
equipped with a cushion ride system, such as the cushion ride
system generally at 210, the accumulator may be recharged when
piston rod 318 reaches its maximum extension and valves 120 and 220
are opened or when valve 222 is closed and valves 120 and 220 are
opened.
[0030] It will be appreciated by those of ordinary skill in the art
that the embodiments described herein are not intended to limit the
scope of the present invention. Various combinations and
modifications of the embodiments described herein may be made
without departing from the scope of the present invention and all
modifications are meant to be included within the scope of the
present invention. Thus, while certain exemplary embodiments and
details have been described for purposes of describing the
invention, it will be apparent to those of ordinary skill in the
art that various changes in the invention described herein may be
made without departing from the scope of the present invention,
which is defined in the appended claims.
* * * * *