Title:
Vertical outrigger leg
Kind Code:
A1


Abstract:
An outrigger assembly for the support and stabilization of a mobile work machine, such as a vehicle-mounted telescopic belt conveyor, while the machine is operating. The outrigger assembly includes a vertical outrigger leg assembly. The vertical outrigger leg assembly is attached to the end of a horizontally extending member and includes multiple telescopically extendable sections that extend until a support pad is in contact with the work surface, then raise the mobile work machine off of the ground into a stabilized position. The multiple leg sections allow for increased vertical lifting distance, thus improving stability on uneven work surfaces, and allow the outrigger assembly to be used on larger machines.



Inventors:
Mayer, Martin G. (Reutlingen, DE)
Application Number:
10/932134
Publication Date:
03/02/2006
Filing Date:
09/01/2004
Primary Class:
International Classes:
E02F3/00
View Patent Images:
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Primary Examiner:
PHAN, HAU VAN
Attorney, Agent or Firm:
Joseph D. Kuborn (Milwaukee, WI, US)
Claims:
1. An outrigger assembly for stabilizing a mobile work machine, comprising: an outrigger leg housing having an open interior; a hydraulic cylinder having an outer wall and an open interior, the hydraulic cylinder being operatively positioned within the outrigger leg housing and movable within the outrigger leg housing between a retracted position and an extended position; a leg member telescopically positioned within the hydraulic cylinder, the leg member being moveable between a retracted position in which the leg member is contained within the hydraulic cylinder and an extended position in which the leg member extends from the hydraulic cylinder, and wherein the hydraulic cylinder and the leg member are each movable from the retracted position to the extended position and from the extended position to the retracted position by hydraulic pressure.

2. The outrigger assembly of claim 1 wherein the outrigger leg housing, the hydraulic cylinder, and the leg member are centered on a common axis.

3. The outrigger assembly of claim 2 wherein the common axis is a vertical axis.

4. The outrigger assembly of claim 3 wherein the movement of the hydraulic cylinder and leg member is along the vertical axis.

5. The outrigger assembly of claim 1 wherein the hydraulic cylinder forms a seal between its outer wall and the open interior of the outrigger leg housing and a seal between its open interior and the leg member.

6. (canceled)

7. The outrigger assembly of claim 1 wherein the outrigger leg housing includes a first hydraulic inlet and a second hydraulic inlet.

8. The outrigger assembly of claim 7 wherein hydraulic pressure is applied to the first hydraulic inlet to move both the hydraulic cylinder and the leg member from the retracted position to the extended position.

9. The outrigger assembly of claim 8 wherein hydraulic pressure is applied to the second hydraulic inlet to move both the hydraulic cylinder and the leg member from the extended position to the retracted position.

10. The outrigger assembly of claim 1 wherein the outer wall of the hydraulic cylinder includes a hydraulic passage to communicate the hydraulic fluid to the leg member.

11. The outrigger assembly of claim 1 further comprising a support pad mounted to a lower end of the leg member.

12. The outrigger assembly of claim 1 wherein the hydraulic cylinder and the leg member are independently movable between their respective extended positions and retracted positions.

13. The outrigger assembly of claim 1 further comprising: a stationary support housing mountable to the work machine; an inner housing telescopically positioned within the stationary support housing, wherein the inner housing is connected to and supports the outrigger leg housing; and a drive cylinder operatively positioned between the stationary support housing and the inner housing, the drive cylinder being operable to move the inner housing between a retracted position in which the inner housing is positioned within the stationary support housing and an extended position in which the inner housing extends from the stationary support housing.

14. The outrigger assembly of claim 13 wherein the outrigger assembly is connected to a distal end of the inner housing.

15. The outrigger assembly of claim 13 wherein the drive cylinder, the hydraulic cylinder, and the leg member are independently movable such that the hydraulic cylinder and the leg member can be extended while the inner housing is positioned at any location between its extended and retracted positions.

16. An outrigger assembly for stabilizing a mobile work machine, comprising: an outrigger leg housing having an open interior; a hydraulic cylinder having an outer wall and an open interior, the hydraulic cylinder being operatively positioned within the outrigger leg housing and movable within the outrigger leg housing between a retracted position and an extended position; a leg member telescopically positioned within the hydraulic cylinder, the leg member being movable between a retracted position in which the leg member is contained within the hydraulic cylinder and an extended position in which the leg member extends from the hydraulic cylinder; a first hydraulic inlet located in the outrigger leg housing; a second hydraulic inlet located in the outrigger leg housing; wherein pressurized hydraulic fluid is applied to the first hydraulic inlet to move the hydraulic cylinder and the leg member from their retracted positions to their extended positions; and wherein pressurized hydraulic fluid is applied to the second hydraulic inlet to move the hydraulic cylinder and the leg member from their extended positions to their retracted positions.

17. The outrigger assembly of claim 16 wherein the outrigger assembly is perpendicularly connected to a horizontally oriented inner housing.

18. The outrigger assembly of claim 17 wherein the inner housing is positioned within a stationary support housing connected to the mobile work machine.

19. The outrigger assembly of claim 18 wherein the inner housing is extendably connected to the stationary support housing by a drive cylinder.

20. The outrigger assembly of claim 16 wherein the hydraulic cylinder forms a seal between its outer wall and the outer wall of the outrigger leg housing and a seal between its outer wall and the leg member.

21. (canceled)

22. An outrigger assembly for stabilizing a mobile work machine, comprising: a vertically oriented outrigger leg housing having an outer wall, a first and second inlet, and an open interior; a vertically oriented hydraulic cylinder telescopically positioned within the outrigger leg housing having an outer wall and an open interior; a vertically oriented leg member with a support pad attached to a lower end of the leg member, wherein the leg member is telescopically positioned within the hydraulic cylinder, the leg member being moveable from a retracted position to an extended position; a stationary support housing attached to the mobile work machine; and an inner housing connected within the stationary support housing, wherein the inner housing is extendable by a drive cylinder utilizing hydraulic pressure; and wherein the leg assembly is movable from a retracted position to an extended position by pressurized hydraulic fluid supplied through the first inlet and the leg assembly is movable from an extended position to a retracted position by pressurized hydraulic fluid supplied through the second inlet; and wherein a plurality of outrigger leg assemblies are mounted to the mobile work machine and the drive cylinders and leg assemblies are independently movable.

23. The outrigger assembly of claim 16 further comprising: a hydraulic passage located within the outer wall of the hydraulic cylinder; an open interior within the outrigger leg housing; and an open interior within the hydraulic cylinder; wherein the open interior of the outrigger leg housing is in fluid communication with the open interior of the hydraulic cylinder through the hydraulic passage.

24. The outrigger assembly of claim 23 wherein pressurized hydraulic fluid is supplied through the first inlet to the open interior of the outrigger leg housing to move the hydraulic cylinder and leg member from a retracted position to an extended position; and wherein pressurized hydraulic fluid is supplied through the second inlet to the hydraulic passage to move the hydraulic cylinder and leg member from an extended position to a retracted position.

Description:

BACKGROUND OF THE INVENTION

The present invention relates to an outrigger assembly for stabilizing a mobile work machine. More specifically, the present invention is an outrigger assembly for stabilizing a self-propelled, vehicle-mounted conveyor system used to place concrete or other materials in a desired location where the vertical movement of the outrigger leg is actuated by utilizing multiple cylinders to direct the multiple telescoping leg sections.

Vehicle-mounted, extendable material placement systems have been in use for some time and are the subject of numerous prior patents. In such vehicles, a telescopic or sectional-unfolding boom extends from a rotating turret attached to the vehicle. The substantial amount of weight extending from the vehicle chassis necessitates the use of outriggers to stabilize the vehicle and prevent the vehicle from tilting or overturning. Extendable material placement systems are most typically utilized during the construction of new buildings. This often requires placement and operation of the vehicle on rough and uneven ground. The use of outriggers increases the footprint of the extendable material placement system thereby making it more stable. For the outrigger legs to properly serve their function, the outrigger legs must have sufficient clearance to fully extend out over the uneven ground.

Vehicle-mounted, extendable concrete conveyor systems, such as shown in U.S. Pat. No. 4,624,357 has been in use for some time. In such vehicles, a discharge conveyor assembly includes a telescoping boom having its base pivotally mounted to the torque tube of the vehicle chassis. The substantial amount of weight extending from the vehicle chassis necessitates the use of outriggers to stabilize the vehicle and prevent the vehicle from tilting or overturning.

The most common type of outrigger system includes a plurality of telescoping legs that can each be extended from a stationary housing fixed to the vehicle. An example of this type of outrigger is shown in U.S. Pat. No. 4,949,808. This common outrigger assembly employs multiple horizontal telescoping members. Because both the discharge conveyor assembly and the infeed conveyor assembly are rotatable about a turnable assembly mounted to the vehicle chassis, multiple sections must be used to cover the necessary distance in order to create an outrigger footprint that will achieve the desired stability. In this common type of outrigger design, both the horizontal and vertical travel over the outrigger leg is achieved by a single hydraulic cylinder.

A vehicle-mounted conveyor system presents unique problems in the design of the outrigger assembly. The outrigger assembly must be mounted to the vehicle in a way such that the conveyor assemblies can rotate about the vehicle without contacting the outrigger assemblies. However, due to the length of the extendable boom contained on the discharge conveyor, a significant amount of weight positioned away from the center of gravity of the vehicle must be supported by the vehicle chassis. Therefore, in addition to being designed to avoid contact with the conveyor assemblies, the outrigger assemblies must extend a sufficient distance from the vehicle chassis in order to provide the required stability for the vehicle. The combination of these two requirements dictates that the height the outriggers at their furthest point from the chassis will be limited. Because of this height limit, a single-stage vertical leg will be very limited in its capability to elevate the entire machine into a stable condition. Additionally, uneven terrain on the job site prevents a stable set up unless the vertical legs were of a telescoping design of multiple cylinders used to drive the multiple leg sections.

It is an object of the present invention to provide an outrigger assembly for use with a vehicle-mounted conveyor system to provide the required stability of the vehicle while preventing possible contact between the main discharge conveyor assembly and the individual outrigger. Further, it is an object of the invention to provide a vertical outrigger leg for use on rough, unmade, or uneven ground by extending the frame of the machine laterally and lifting the machine vertically. It is another object of the present invention to provide a plurality of outrigger assemblies in which each outrigger assembly is contained within the overall vehicle width when in its completely retracted position. Additionally, it is an object of the present invention to provide an outrigger assembly that includes a multi-section, vertically telescoping assembly to increase the vertical distance the outrigger leg assembly can travel in order to make solid contact with the ground to establish the desired stability.

SUMMARY OF THE INVENTION

The present invention is an outrigger assembly for use with a mobile work machine, such as a vehicle-mounted telescopic belt conveyor, to stabilize the machine when the machine is operating. The work machine includes a plurality of the individual outrigger assembly to provide multiple points of stabilization for the vehicle when the extendable conveyor is in use.

Each outrigger assembly for stabilizing a mobile work machine includes an outer support housing having an open interior, a hydraulic cylinder movable within the outer support housing and having an open interior, and a leg member telescopically positioned within the hydraulic cylinder. The hydraulic cylinder is operatively positioned within the outer support housing and moves between a retracted position within the outer support housing and an extended position. The leg member also moves from a retracted position in which the leg member is contained within the hydraulic cylinder to an extended position. The outer support housing, the hydraulic cylinder, and the leg member are all centered along a common vertical axis and the hydraulic cylinder and leg member move along this vertical axis.

The hydraulic cylinder and the leg member of the outrigger assembly are each movable by hydraulic pressure supplied through a first hydraulic inlet for movement from the retracted to the extended position and a second hydraulic inlet for movement from the extended to the retracted position. The hydraulic fluid is able to pass from the hydraulic cylinder to the leg member by a hydraulic passage formed in the wall of the hydraulic cylinder.

The outrigger assembly additionally includes a stationary support housing that is mounted to the concrete placing machine, an inner housing that is telescopically positioned within the stationary support housing, and a drive cylinder, that is operably positioned between the support housing and the inner housing. The drive cylinder is operable to move the inner housing between a retracted position in which the inner housing is positioned within the support housing and an extended position in which the inner housing extends from the stationary support housing. The outrigger assembly is vertically oriented and connected to the extendable end of the inner housing. The drive cylinder, hydraulic cylinder, and leg member are all independently operable such that the hydraulic cylinder and leg cylinder, or both, can be extended while the inner housing is in either the retracted position or the extended position.

The outrigger assembly of the invention includes a vertically oriented outrigger leg housing having an open interior, a vertically oriented hydraulic cylinder having an open interior and being operably positioned within the support housing, a vertically oriented leg member that is telescopically positioned within the hydraulic cylinder, and an inner housing that is extendably movable relative to the mobile work machine. The outrigger leg housing is aligned along the same vertical axis as the hydraulic cylinder and the leg member and is connected to the distal end of the inner housing.

In a preferred embodiment of the invention, the inner housing extends from the mobile work machine until the proper extended width is achieved. Both the hydraulic cylinder and the leg member may be extended vertically by use of hydraulic pressure to a ground-engaging position with the support pad mounted at the lower end of the leg member contacting the ground. Further extension of the hydraulic cylinder and the leg member results in the lifting of the vehicle body off the ground to further stabilize the machine during operation. An advantage of the outrigger assembly of the present invention is that it affords greater stabilization for the mobile work machine because of the expanded outrigger leg horizontal reach positions, and increased vertical lift whereby the mobile work machine may be stabilized more effectively in a greater range of ground types and slopes.

The preferred embodiment of the invention also calls for the implementation of a plurality of outrigger legs attached to the mobile work machine.

Various other features, objects, and advantages of the invention will be made apparent from the following description taken together with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings illustrate the best mode presently contemplated of carrying out the invention.

In the drawings:

FIG. 1 is a side elevation view of a self-propelled vehicle including a vehicle-mounted conveyor system and a plurality of outrigger assemblies constructed in accordance with the present invention;

FIG. 2 is a top plan view of the vehicle illustrated with the outrigger assemblies of the present invention in their fully extended, ground-engaging position;

FIG. 3 is a rear view of the vehicle with the rear outrigger assemblies in their fully retracted position;

FIG. 4 is a rear view similar to FIG. 3 illustrating the outrigger assemblies in their fully extended position;

FIG. 5 is a section view showing an outrigger assembly of the present invention in its fully retracted position;

FIG. 6 is a section view of an outrigger leg assembly of the present invention in which the leg member is extended and the hydraulic cylinder is in the retracted position;

FIG. 7 is a cut away view of an outrigger leg assembly of the present invention in the fully extended, ground-engaging position with both the leg member extended and the hydraulic cylinder extended.

DETAILED DESCRIPTION OF THE INVENTION

A mobile work machine, such as a self-propelled vehicle 20 including a vehicle-mounted conveyor system 22 for transporting an aggregate material such as concrete is best shown in FIGS. 1 and 2. The vehicle 20 includes a conventional cab 24 and a torque tube 26. The vehicle 20 is of a size such that it does not exceed the legal dimensional limits for over the highway travel.

The conveyor system 22 includes an in-feed conveyor assembly 28 that receives the supply of aggregate material, such as concrete, from a supply source 30 and transports the material upward along a moving in-feed conveyor belt. The in-feed conveyor assembly 28 is rotatable about the vehicle 20 such that the in-feed conveyor assembly 28 can receive the supply of material at various locations around the vehicle 20.

The conveyor system 22 includes a main turret 32 that is rotatably mounted to the torque tube 26 of the vehicle 20. A discharge conveyor assembly 34 is pivotally mounted to the main turret 32 about a horizontal pivot axis and also rotates along with the main turret 32. Specifically, the discharge conveyor assembly 34 includes a telescoping boom 36 having its base end mounted in a cantilever manner to the main turret 32. The discharge end 38 of the discharge conveyor assembly 34 is extendable away from the main turret 32 to control placement of the conveyed aggregate from the discharge end 38.

As can be seen in FIG. 2, the vehicle 20 includes a pair of front outrigger assemblies 40a and 40b, and a pair of rear outrigger assemblies 42a and 42b. Each of the outrigger assemblies extends from the torque tube 26 in a direction transverse to the longitudinal axis of the vehicle 20. The outrigger assemblies are operable to elevate the vehicle 20 above the ground and stabilize the vehicle to allow the discharge conveyor assembly 34 to be extended in the manner shown in FIG. 1. In general, each of the outrigger assemblies 40a, 40b, 42a and 42b includes identical operating components and function in an identical manner such that the single description of the outrigger assembly below is applicable to each of the outrigger assemblies. The four individual outrigger assemblies shown in FIGS. 1 and 2 provide the required stabilization for the vehicle 20 during operation of the telescoping boom 36.

FIG. 3 illustrates the rear outrigger assembly 42b in its fully retracted position. The outrigger assembly 42b includes a stationary support housing 44 that is securely mounted to the vehicle chassis and is positioned behind the rear wheels 47 of the vehicle 20.

The rear outrigger assembly 42b is shown in FIG. 4 in its fully extended, ground-engaging position. When in the fully extended position, the movable inner housing 46 extends from the stationary support housing 44. An outrigger leg assembly 48 is securely attached to the outermost end of the inner housing 46. The outrigger leg assembly 48 includes an outrigger leg housing 54, a hydraulic cylinder 52, and a leg member 50, all of which are vertically aligned along a common central axis 118. The leg member 50 is telescopically movable into and out of the hydraulic cylinder 52 which, in turn, is telescopically movable into and out of the outrigger leg housing 54. A support pad 56 is mounted to the leg member 50. The support pad 56 contacts the ground 60 when the outrigger assembly 42b is in its fully extended, ground-engaging position. In addition to the rear outrigger assembly 42b, FIG. 4 also illustrates the rear outrigger assembly 42a in its fully extended position. The combination of the pair of fully extended rear outrigger assembles 42a and 42b elevate the rear wheels 47 of the vehicle 20 above the ground 60, as can be clearly seen in FIG. 4.

FIGS. 5, 6 and 7 illustrate the detailed construction of the rear outrigger assembly 42b, although the following description is equally applicable to each of the outrigger assemblies. As previously discussed, the outrigger assembly 42b includes the stationary support housing 44 securely connected to the chassis of the vehicle 20. The support housing 44 is formed from a generally rectangular outer shell 45 constructed from a metallic material, such as steel. In the preferred embodiment of the invention, the support housing 44 has an overall length of approximately 98 inches, which is approximately equal to the width of the vehicle chassis.

As can be seen in FIG. 5, the outer shell 45 of the support housing 44 defines a generally open interior 64 that extends between a closed back end 66 and open-front end 68. The front end 68 of the support housing 44 includes a reinforcing ridge 70 extending upward from the outer shell 45. The reinforcing ridge 70 contacts a corresponding reinforcing ridge 72 formed on an outer shell 74 that defines the inner housing 46.

As can be seen in the combined views of FIGS. 2 and 5, the inner housing 46 is also generally rectangular and defines an open interior 76 extending between an open back-end 78 and an open-front end 80. As can be understood in FIGS. 2, 3 and 4, the inner housing 46 is extendable into and out of the open interior 64 defined by the support housing 44. Specifically, the inner housing 46 is movable between a retracted position in which nearly the entire inner housing 46 is contained within the support housing 44, and an extended position in which a substantial portion of the inner housing 46 extends from the support housing 44, as shown in FIG. 4.

In the preferred embodiment of the invention, the means for moving the inner housing 46 into and out of the support housing 44 is a first drive cylinder 82. The first drive cylinder 82 is a fluid-actuated cylinder having a cylinder body 84 and an extendable cylinder rod 86. The cylinder body 84 is contained in the open interior 76 defined by the outer shell 74 of the inner housing 46 and extends between a first end 88 and a second end 89. The second end 89 of the cylinder body 84 is securely connected by a pivot pin 91 to the inner surface 90 of a support plate 93 at the closed back end 66 of the stationary support housing 44. Specifically, the pivot pin 91 passes through a mounting block 92 to secure the second end 89 of the cylinder body 84 to the inner surface 90. In this manner, the cylinder body 84 is securely attached to the stationary support housing 44.

The first end 88 of cylinder rod 86 is securely attached to saddle 94 by a mounting pin 96. The saddle 94 is securely attached to the inner surface 95 of the mounting beam 49, which is secured to the inner wall of the inner housing 46. When the first drive cylinder 82 is actuated, the cylinder rod 86 is forced out of the cylinder body 84, causing the inner housing 46 secured to the first end 88 of the cylinder body 84 to move outward. The inner housing 46 continues to move outward relative to the stationary support housing 44 until the cylinder rod 86 is completely extended. When the cylinder rod 86 is fully extended, the inner housing 46 is in its completely extended position.

In the preferred embodiment of the invention, the first drive cylinder 82 is a two-directional fluid-actuated cylinder such that the first drive cylinder 82 can be operated in a reverse direction to retract the cylinder rod 86 into the cylinder body 84 and move the inner housing 46 from the fully extended position to the retracted position.

In the preferred embodiment of the invention, the first drive cylinder 82 is positioned inside the outer shell 74 of the inner housing 46. Thus, when the inner housing 46 is in its extended position, the first drive cylinder 82 is concealed within the inner housing 46, as can be seen in FIG. 4.

The outrigger leg assembly 48 is perpendicularly connected to the mounting beam 49, which is securely attached to the inner surface of the inner housing 46. The outrigger leg assembly 48 is vertically oriented and is shown in its completely retracted position in FIG. 5 and in its extended position in FIG. 7. The outrigger leg assembly 48, and specifically the hydraulic cylinder 52 and leg member 50, is vertically movable along the common vertical axis 118 from the retracted position (FIG. 5) to the extended ground-engaging position (FIG. 7) in which the support pad 56 contacts the ground 60. The support pad 56 is connected to a first end 50a of leg member 50. The second end 50b of the leg member 50 is movably positioned within hydraulic cylinder 52.

As shown in FIG. 7, the hydraulic cylinder 52 has a first end 52a and a second end 52b and is movably positioned within outrigger leg housing 54. The hydraulic cylinder 52 is further comprised of an outer wall 52c having a hydraulic passage 102 disposed within the outer wall 52c and an open interior 98 surrounded by the outer wall 52c.

The outrigger leg housing 54 generally includes a bottom end 54a, a top end 54b, and an outer wall 54c. The outer wall 54c defines an open interior 100. The outer wall 54c includes a first hydraulic inlet 58 and second hydraulic inlet 60 connected to the outrigger leg housing 54 at top end 54b and bottom end 54a respectively. A first hydraulic channel 59 passes through outer wall 54c connecting the first hydraulic inlet 58 to the open interior 100 and a second hydraulic channel 61 connects second hydraulic inlet 60 to a first hydraulic cavity 104. As shown in FIG. 6, the first hydraulic cavity 104 is defined as the space between the second end 52b of the hydraulic cylinder and the bottom end of the outrigger leg housing 54a.

In the preferred embodiment of the invention, the means for moving the leg assembly 48 from its retracted position depicted in FIG. 5 to its extended position depicted in FIG. 7 is hydraulic pressure. Starting in the retracted position depicted in FIG. 5, hydraulic fluid is pumped through first hydraulic inlet 58 and first hydraulic channel 59 of leg assembly 48 into the open interior 100. As the pressure within the open interior 100 increases, the pressure is displaced against the second or top ends of the leg member 50b and the hydraulic cylinder 52b. A first cylinder seal member 108 and a second cylinder seal member 112 allow the hydraulic pressure in the open interior 100 to force the hydraulic cylinder 52 to telescope out of the outrigger leg housing 54 and the leg member 50 to telescope out of the hydraulic cylinder 52.

As shown in FIG. 6, the leg member 50 continues to extend until the first end 52a of the hydraulic cylinder 52 comes in contact with the second end 50b of the leg member 50. As shown in FIG. 7, the hydraulic cylinder 52 also continues to extend until the second end 52b of the hydraulic cylinder comes in contact with the bottom end 54a of the outrigger leg housing 54 and the outrigger leg assembly is in its fully extended position. The hydraulic pressure is maintained in the open interior 100 while the outrigger leg 48 is extended by the first cylinder seal 108 located between the outer surface of the second end 52b of the hydraulic cylinder and the inner surface of the outrigger leg housing outer wall 54c. A cylinder seal 112 is positioned between the outer surface of the leg member second end 50b and the inner surface of the hydraulic cylinder outer wall 52c.

In the preferred embodiment of the invention, the leg assembly 48 also moves from its fully extended position depicted in FIG. 7 to its retracted position depicted in FIG. 5 by means of hydraulic pressure. To effect such movement, hydraulic fluid is pumped into the second hydraulic inlet 60 and through the outrigger leg housing outer wall 54c by means of the second hydraulic channel 61. The supply of hydraulic fluid is received in the first hydraulic cavity 104, as shown in FIG. 7. As the hydraulic pressure within the first hydraulic cavity 104 increases, the pressure is exerted on the hydraulic cylinder second end 52b, forcing the hydraulic cylinder 52 to retract into the open interior 100 of the outrigger leg housing 54. As the hydraulic cylinder 52 retracts into outrigger leg housing 54, the first hydraulic cavity 104 increases in volume. Hydraulic pressure is maintained in the first hydraulic cavity 104 due to the first cylinder seal 108 and a second cylinder seal 110. The second cylinder seal 110 is between the interior surface of the outrigger leg housing bottom 54a and the outer surface of the hydraulic cylinder outer wall 52c. As the hydraulic cylinder 52 is retracted, hydraulic fluid is allowed to flow out of the open interior 100 through the cavity 59 and the inlet 58.

When the hydraulic cylinder 52 sufficiently retracts into the open interior 100 of the outrigger leg housing 54, the inflow end 116 of hydraulic passage 102 connects to the first hydraulic cavity 104 and allows hydraulic fluid to flow from the first hydraulic cavity 104 to a second hydraulic cavity 106 located between the bottom surface of the leg member second end 50b and the top surface of the hydraulic cylinder first end, as shown in FIG. 6. As the hydraulic pressure within the second hydraulic cavity 106 increases, the leg member 50 is retracted into the open interior 98 of the hydraulic cylinder 52. As the hydraulic pressure within the first hydraulic cavity 104 and the second hydraulic cavity 106 continues to increase, the hydraulic cylinder 52 and the leg member 50 are further retracted into the open interiors 100 and 98. As discussed, the hydraulic fluid that had been residing in the open interiors 100 and 98 is forced back through the first hydraulic channel 59 and the first hydraulic inlet 58.

Although the first drive cylinder 82, the outrigger leg housing 54 and the hydraulic cylinder 52 are shown and described as being fluid-driven cylinders, it is contemplated by the inventors that each of these cylinders could be replaced by an equivalent means for driving the inner housing 46, the hydraulic cylinder 52, and the like member 50 between their extended and retracted positions. For example, it is contemplated by the inventors that a rotating screw drive mechanism, air cylinder, or other equivalent structure could replace the fluid-driven cylinders shown.

In the preferred embodiment of the invention the outrigger assemblies 40a, 40b, 42a, and 42b operate as discussed above utilizing a single source of hydraulic pressure. This results in optimal operation of the outrigger assembly during use upon ground of a varying elevation. When the outrigger assemblies 40a, 40b, 42a, and 42b begin to extend from their fully retracted position, hydraulic pressure will be supplied to each assembly evenly and the leg members 50 and hydraulic cylinders 52 will extend evenly. However, once a support pad 56 of one of the outrigger leg assemblies 40a, 40b, 42a, and 42b contacts the ground, it will require less pressure to extend the other outrigger leg assemblies. The outrigger leg assembly in contact with the ground will stop extending while the other outrigger leg assemblies continue to extend until all of the support pads are in contact with the ground. The pressure required to extend each of the outrigger leg assemblies will then be even and the mobile work machine 20 will rise and be supported in a level fashion despite the uneven extension of each of the outrigger leg assemblies. This maintains the mobile work machine's center of gravity between the outrigger leg assemblies, thus ensuring the stability of the mobile work machine 20 in its raised position, despite the ground underneath each outrigger leg assembly being of a different elevation.

Various alternatives and embodiments are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter regard as the invention.

While the invention has been described with reference to a preferred embodiment, those skilled in the art will appreciate that certain substitutions, alterations and omissions may be made without departing from the spirit thereof. Accordingly, the foregoing description is meant to be exemplary only and should not be deemed limitative on the scope of the invention set forth with the following claims.