Patent Publication Number: US-6213244-B1

Title: Multi function control mechanism

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention is directed to a multi function control mechanism for a work vehicle which independently positions hydraulic control valves through the manipulation of a single control lever. 
     2. Description of the Prior Art 
     In operating work vehicles such as crawler dozers, the operator controls a plurality of work operations through manipulating various control levers that control the positioning of hydraulic control valves and thereby the flow of hydraulic fluid to hydraulic cylinders of a work implement. It is desirable to control a number of work operations from a single control lever. Typically three function control levers have a T-bar shaped control handle that can be moved through orthogonal control arcs to operate the first two functions and twisted to control a third function. It is desirable that the control lever be manipulated to operate each of the functions independently or in unison with the other functions. 
     Such three function control levers are used on crawler dozers manufactured and marketed by the assignee of the present application, for controlling the position of the working blade. These control levers are operatively coupled to the supporting frame of the dozer by a series of universal joints and/or ball joints. See U.S. Pat. Nos. 3,131,574, 3,388,609 and 4,938,091 all of which are assigned to the assignee of the present patent application. U.S. Pat. Nos. 4,536,055, 4,978,273 and 5,429,037 disclose other examples of three function control mechanisms. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a control mechanism wherein cross talk between controlled functions and the dead band when controlling a specific function are minimized. 
     Three independent functions are controlled from a single control lever. The lever is mounted on a universal joint having a slip yoke, a flanged yoke and a cross member extending between the two yokes and defining a first transverse pivot axis and a second transverse pivot axis. The slip yoke is provided with a first mounting assembly in the same plane as the cross member and a second mounting assembly also in the same plane as the cross member. 
     The first function is controlled by the fore-and-aft movement of the control lever. Such a fore-and-aft movement pivots the slip yoke about the first transverse pivot axis moving the first mounting assembly which is coupled to a first link. The first link in turn moves a first hydraulic control valve. The first hydraulic control valve is shifted along a first shift axis. The first hydraulic control valve is provided with first control valve ball joint that is coupled to the first link. The first control valve ball joint is in line with the first shift axis. 
     The second function is controlled by the side-to-side movement of the control lever. Such a side-to-side movement pivots the slip yoke about the second transverse pivot axis moving the second mounting assembly which is coupled to a second link. The second link in turn moves a second hydraulic control valve. The second hydraulic control valve is shifted along a second shift axis. The second hydraulic control valve is provided with second control valve ball joint that is coupled to the second link. The second control valve ball joint is in line with the second shift axis. 
     The third function is controlled by the twisting movement of the control lever. A downwardly extending strap is welded to the control lever and is provided with a third mounting assembly. The third mounting assembly is coupled to a third linkage for controlling the movement of the third hydraulic control valve. The third linkage comprises a rod coupled to the third mounting assembly and extending to the first arm of a bell crank. The second arm of the bell crank is coupled to a third link that is pinned to the third hydraulic control valve. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side view of a crawler dozer. 
     FIG. 2 is an upward perspective view of the three function control mechanism. 
     FIG. 3 is a downward perspective view of the three function control mechanism. 
    
    
     DETAILED DESCRIPTION 
     FIG. 1 illustrates a work vehicle in the form of a crawler dozer  10 . The crawler dozer  10  is provided with a supporting frame  12  and ground engaging tracks  14 . Ground engaging wheels may be used in place of ground engaging tracks  14 . The dozer  10  is provided with a working member or blade  16  the position of which is controlled by hydraulic cylinders. More specifically, the blade is raised and lowered by hydraulic cylinders  18  the position of which are controlled by the operator through T-bar control lever  20  located in operators area  22 . By manipulating the control lever  20  fore-and-aft the blade  16  is raise and lowered. To tilt the blade  16  about the longitudinal axis, the control lever  20  is manipulated side-to-side which drives another hydraulic cylinder tilting the blade. To angle the blade  16  about a lateral axis the control lever  20  is twisted. In the illustrated embodiment, the three function control mechanism is described as being located on a crawler dozer, to which it is particularly well suited, however the invention is not so limited and may be applied to other control systems needing single lever three function control. 
     The three function control mechanism controls the positioning of three hydraulic control valves  24 ,  26  and  28  located in valve stack  30 . The first hydraulic control valve  24  is the raise/lower control valve and is manipulated by moving the control lever  20  fore-and-aft to raise and lower the dozer blade  16 . The second hydraulic control valve  26  is the tilt control valve and is manipulated by moving the control lever  20  side-to-side to tilt the dozer blade  16  about the vehicle&#39;s longitudinal axis. The third hydraulic control valve  28  is the angle control valve and is manipulated by twisting the control lever to angle the blade  16  about a vertical axis. 
     The control lever  20  defines a lever axis  32 . The lever  20  is coupled to a universal joint  34 . The universal joint is formed from a flanged yoke  36  and a slip yoke  38  which are joined together by a cross member  40 . The flange yoke  36  is mounted to supporting frame  12  by mounting bolts  42 . The flanged yoke  36  is provided with two upwardly extending ears  44  which are parallel to the control lever axis  32  and to which the cross member  40  is pivotally secured thereby defining a first transverse pivot axis. The slip yoke  38  is provided with two downwardly extending ears  46  that are parallel to the control lever axis  32  and are pivotally connected to the cross member  40  thereby defining a second transverse pivot axis that is orthogonal to the first transverse pivot axis of the flanged yoke  36 . Both transverse pivot axes intersect and are perpendicular to the control lever axis  32 . The slip yoke  36  defines a sleeve  47  the interior of which is provided with two bearing races, not shown, which receive the control lever  20  so that it can be twisted in the sleeve  47 . The slip yoke is also provided with a radially extending flange  48 . The sleeve  47 , the two downwardly extending ears  46  and the radially extending flange  48  form a single integral part. First and second downwardly extending mounting assemblies  50  and  52  are secured to mounting apertures in the radially extending flange  48 . The first mounting assembly  50  is provided with a first ball joint  54  and the second mounting assembly  52  is provided with a second ball joint  56 . The ball joints  54  and  56  of the mounting assemblies  50  and  52  are orthogonal to one another and are located on the two transverse pivot axes defined by the ears of the respective yokes. First ball joint  54  of first mounting assembly  50  is positioned adjacent to the transverse pivot axis defined by the downwardly extending ears of the slip yoke  38 . Similarly, the second ball joint  56  of the second mounting assembly  52  is positioned adjacent to the transverse pivot axis defined by the upwardly extending ears of the flanged yoke  36 . By having the ball joints  54  and  56  in line with the orthogonal pivot axes, cross talk when operating the control lever  20  is minimized. It should be noted that the radially extending flange  48  may comprise a single segment as illustrated, or two segments each one defining a mounting aperture for the mounting assemblies. 
     The first ball joint  54  is coupled to a first link  58 . The first link  58  is coupled to the first hydraulic control valve  24  by a first control valve ball joint  60 . The second ball joint  56  is coupled to a second link  62 . The second link  62  is coupled to the second hydraulic control valve  26  by a second control valve ball joint  64 . Both control valve ball joints  60  and  64  are aligned with the shift axes of the respective control valve so that again cross talk between control operations is minimized. 
     The above discussion was focussed on controlling the first two operations by moving the control lever  20  fore-and-aft, and right and left. The third control operation is accomplished by twisting the control lever  20  manipulating a third mounting assembly  66 . The third mounting assembly is coupled to the control lever  20  through a downwardly extending strap  70 . The strap  70  is welded to the control lever  20 . The third mounting assembly  66  comprises a third ball joint that is operatively coupled to a third linkage. The third linkage is defined by a control rod  72  having a first end that is coupled to the third ball joint of the third mounting assembly  66  and an opposite end having a fourth ball joint  74  that is coupled to the first arm  76  of a bell crank  78 . The bell crank  78  is pivotally mounted to the supporting frame  12  and is provided with a second arm  80  that is coupled to a third link  82  that is pinned to control valve  28  by pin  84 . It should be noted that the third control valve  28  may also be provided with a control valve ball joint in a manner similar to the first two control valves. But in the current application the third control function is not widely used and a pin joint is deemed adequate. 
     The invention should not be limited by the above described embodiments, but should be limited solely by the claims that follow.