Vehicle stabilizer attachment and method
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to an extendible and tractable linear stabilizer which is readily attached to and detached from the frame of a work vehicle. Usually such stabilizers operate in pairs, and when the stabilizers are extended more down pressure can be exerted on a ground engaging implement carried by the vehicle and the stabilizers act as a brake holding the work vehicle in position during operation of the implement. 
     2. Description of the Prior Art: 
     U.S. Pat. No. 3,630,317 Jacobsson shows two hydraulically operated stabilizers on a three-wheel fork truck which stabilizers are automatically actuated when the load carriage of the vehicle is raised. 
     U.S. Pat. No. 4,018,458 Shumaker shows a stabilizer for a vehicle which consists of a pair of telescopic members with one member being mounted on the vehicle and the other member having a ground engaging foot supported on the free end thereof for rotation in a horizontal plane. The stabilizer incorporates latch means between the telescopic member and the foot for holding the foot in a plurality of rotated positions with respect to the telescopic member, whereby the angular position of maximum stability for the vehicle can be varied. 
     U.S. Pat. No. 4,082,197 Stedman shows an articulated vehicle having rear and front frames pivotally connected together and a pair of steering cylinders pivotally connected between the rear and front frames for pivoting them relative to each other. A telescopic boom is pivotally mounted on the rear frame and has a work implement, such as a fork, attached to the end of the boom. A pair of lift cylinders are pivotally connected to opposite sides of the front frame and to a ground engaging plate or plates. The lift cylinders are extended to engage the plate or plates with the ground to lift the rear frame relative to the front frame while simultaneously maintaining the front frame in contact with the ground. Upon alternate extension and retraction of the steering cylinders, the rear frame pivots (slues) relative to the front frame to place the work implement into an infinite number of work positions. 
     Swedish patent No. 7700902-5 shows a vehicle having two pivotally mounted wheels adjacent one end of the vehicle which are operated to be raised and lowered by a pair of hydraulic cylinders. The two hydraulic cylinders are operated jointly by a hydraulic valve having raise and lower positions and an intermediate neutral position. When the valve is in neutral a hydraulic connection between the head ends of the two cylinders and another hydraulic connection between the rod ends of the two cylinders permit hydraulic fluid to circulate between the two cylinders to allow the pivotally mounted wheels to adjust to different heights to accommodate the wheels and vehicle to uneven terrain. 
     In addition to the foregoing patented prior art there is unpatented prior art which is discussed in detail hereinafter. 
     SUMMARY OF THE INVENTION 
     In the present invention a structure and method provide for readily attaching a linear stabilizer attachment to a vehicle and readily detaching it again. The attachment is secured to the vehicle frame by a latch mechanism adjacent one end of the attachment and another connection at the other end of the attachment. The stabilizer attachment is telescopic and is extended and retracted by an internal hydraulic cylinder; hydraulic hoses from such cylinder are connected to hydraulic hoses on the vehicle. 
     When two of these stabilizers are used together the stabilizer cylinders are connected together hydraulically so when the stabilizer control valve is actuated both stabilizers extend and retract together. Because of the hydraulic connections the stabilizers automatically compensate for uneven terrain on tilt of the work vehicle, so that both of the stabilizers remain in contact with the ground when extended. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 is a profile view of a vehicle embodying this invention, 
     FIG. 2 is a view of the same vehicle with the near stabilizer extended, 
     FIG. 3 shows a rear view of the same vehicle which employs two of the stabilizer attachments according to the present invention, one on each side, 
     FIG. 4 shows a partial perspective view of the upper end of a stabilizer, 
     FIG. 5 shows an exploded view of a prior art construction, 
     FIG. 6 shows how the prior art construction is assembled on a vehicle, 
     FIG. 7 is a view of the stabilizer of the present invention, 
     FIG. 8 is a partial view of the stabilizer of this invention, 
     FIG. 9 is another view of the same stabilizer, 
     FIG. 10 is a fragmentary diagram illustrating the lower connection of a stabilizer with the frame of a vehicle, and 
     FIG. 11 shows the hydraulic circuit for two of the stabilizers. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 of the drawing shows a detachable stabilizer 10 according to the present invention for a vehicle 11. It is connected to the upright or stanchion portion 14 of the vehicle frame 15. FIG. 2 of the drawing is the same as FIG. 1 except that the near stabilizer 10 is extended. FIG. 3 is a rear view of the same vehicle 11 showing two stabilizers adjacent opposite sides respectively, both of which have been extended. FIG. 4 is a partial perspective view of the upper end of stabilizer 10. 
     In FIGS. 5 and 6 a prior art stabilizer is indicated by the numeral 22 and the vehicle is indicated by the numeral 20 in FIG. 6; both views are perspective views from the right rear as compared to the left side perspective views of FIGS. 1 and 2. 
     Included in FIG. 5 is a stanchion member 24 which is a part of the frame of the vehicle 20, and a plate 26 which is secured between channel member 28 and stanchion member 24 by means of bolts 32 and nuts 33 and a plurality of holes 29, 30 and 31. The tube formed by members 26,28 is the outer structure of the stabilizer and it contains within it an inner telescopically movable member 34. Member 34 has at the bottom a ground engaging flange 36 and a cleat 38 secured to the flange 36. The stabilizer 22 is operated by means of an internal hydraulic cylinder 40 which extends between a cross-pin 41 at the top of housing 28 and a pin 42 at the bottom which extends through the inner slide member 34. 
     FIG. 7 of the drawing shows a stabilizer attachment 10 according to the present invention. It is on the right side of the vehicle and thus is the mirror image of the one appearing in FIG. 1 of the drawing. It includes an outer tubular member 52 of generally square cross-section, and an inner telescopic tubular member 54. Base 56 with cleat 58 thereon is secured to the lower extremity of member 54. A hydraulic cylinder 60 inside the stabilizer structure is connected between a pin 62 near the top of outer member 52 and inner member 54 at the bottom where the connecting pin is indicated by the numeral 64. The stabilizer can be retracted or extended as illustrated in FIGS. 1 and 2 by the operation of hydraulic cylinder 60; it is supplied with pressurized hydraulic fluid for double acting operation through hoses 66 and 68. 
     In order to install a stabilizer 10 on the vehicle 11 the connection mechanism indicated generally by the numeral 70 at the top of the stabilizer is utilized. As shown in FIG. 9 the mechanism 70 has an extended unlatched position wherein the outer tube 52 is lowered with respect to a hanger 72 by turning nut 74 downwardly to the position indicated in FIG. 9. The stud bolt 76 is connected to hanger 72. Bracket 78, which rests on nut 74, is secured to outer tube 52. To install this stabilizer on the machine the hanger 72, as it appears in FIG. 9, is hung over a boss 73 which projects outwardly from the frame 15 of the vehicle. Then, the nut 74 is turned to raise the flange 78 which is connected to outer tube 52 to the raised position as shown in FIG. 8 wherein the stabilizer is firmly secured to the vehicle. This is because hanger 72 is restrained from movement by being between flange 73a on boss 73 and a bracket 75 at the top end of outer tube 52. When outer tube 52 moves upwardly a bracket 84 at the bottom of the tube 52 of the stabilizer moves upwardly into a latching relationship with a member 85 extending downwardly from the frame 15 of the machine; this secures the bottom of the stabilizer firmly in place. FIG. 10 shows the member 85 extending downwardly from frame 15 and bracket 84 extending inwardly from tube 52. 
     When the boss 73, the bracket 85 and hydraulic hoses 67 and 69 are in place on vehicle 11, only three steps are required to install the stabilizer 10 of this invention on the vehicle. The first is to hang the stabilizer 10 on the boss 73. The second is to operate nut 74 to secure the upper connection, which also secures the bottom connection. The third step is to attach two hydraulic hoses 66 and 68 which are parts of the stabilizer to the hoses 67 and 69 on the vehicle. Removing the stabilizer requires the same three steps carried out in reverse order. 
     When two of these stabilizers are used together they may be connected hydraulically as shown in FIG. 11 to not only enhance the down pressure exerted on an implement at the other end of the vehicle and the braking effort but in addition to compensate for uneven terrain. In FIG. 11 the two stabilizer cylinders 60 are connected so that a hydraulic conduit 91 joins the head ends of the cylinders and a hydraulic conduit 93 joins the rod ends of the cylinders. Conduit 66 is connected between conduit 91 and a two-way control valve 95. Conduit 68 is connected between conduit 93 and control valve 95. When valve the 95 is operated to pressurize conduit 91 and thus the head ends of the two cylinders, while pressure is released from conduit 93, the two stabilizers will be extended until they reach the end of their travel or the control valve is returned to neutral. This procedure discharges hydraulic fluid from the rod ends of the two cylinders through conduits 93 and 68. The control valve 95 can be operated in the opposite sense to pressurize conduits 68 and 93 while relieving the pressure in conduits 91 and 66, thus causing the stabilizer cylinders to retract. 
     As shown diagrammatically in FIG. 11 the pistons of the two cylinders are indicated at 97L and 97R. If the stabilizers are on uneven ground the hydraulic circuit provides for fluid to flow from the head end of one of the cylinders to the head end of the other through conduit 91, with similar flow in the other direction through conduit 93 from one of the rod ends to the other rod end. The result of the ground being uneven may be the positioning of the pistons 97L and 97R in the position indicated by the dashed lines in FIG. 11. Other dashed lines show the manner in which the bases 56L and 56R of the stabilizers move in unison with the pistons, 56L moving downwardly and 56R moving upwardly an equal amount. There is a flow of hydraulic fluid in the loop which comprises conduits 91 and 93 and the chambers of the cylinders 60 which causes the stabilizer of this invention to adjust to uneven terrain. 
     While we have described and illustrated herein a preferred embodiment of our invention which is also the best mode contemplated for using it, it will be appreciated that modifications and alterations may be made. Accordingly, it should be understood that we intend to cover by the appended claims all such modifications which fall within the true spirit and scope of our invention. &#34;Hydraulic cylinder&#34; or &#34;cylinder&#34; alone as used herein means a double acting linear hydraulic motor comprising an outer barrel portion with both ends closed and an internal piston forming variable volume chambers between the piston and the respective ends of the barrel portion; the piston is mounted on a rod which projects through the closure at one end of the barrel portion. While reference is made herein to hydraulic hoses it will be appreciated that other equivalent hydraulic conduits can be utilized in the present invention.