Abstract:
A retaining strip arranged to impede the rotation of a stop screw is disclosed. The retaining strip connects with the stop screw on both sides of an attachment bracket. The retaining strip is stretched over the bracket and applies a pressure to the screw that serves to maintain screw rotational position during vehicle operation. The retaining strip does not hamper the adjustment of the screw during adjustment.

Description:
BACKGROUND 
     The present invention relates to an adjustment to match the speed of rotation of drive wheels on opposite sides of a skid steer vehicle or loader when the conventional steering levers are in full forward speed drive positions. An adjustable stop for adjusting the maximum forward speed position for the drive control for the drive motor for one side of the vehicle is accessible from the interior of the loader cab to permit manual, easy adjustments. When both drive controls are in the maximum forward speed position the speed of the drive on each side of the skid steer loader is matched, and the loader will go straight forwardly. 
     The conventional hydrostatic drive systems on skid steer loaders have long been operated by a pair of levers in the cab that move forward and back from a neutral position. The levers rotate bellcranks over a mounted shaft. These bellcranks connect to links leading to separate pump controls for pumps/motors on opposite sides of the loader. 
     U.S. Pat. No. 4,090,411 illustrates such a drive system, utilizing a self centering control. The steering levers are individually mounted and movable, and one lever controls the drive motor direction and speed on the right hand side of the vehicle, and the other lever controls the drive motor direction and speed on the left hand side of the vehicle. At present, the conventional skid steer lever arrangement does not permit quickly accessible adjustment for setting and matching the speeds of the motors on opposite sides of the loader at a full forward speed position of both of the steering levers. 
     SUMMARY 
     The present disclosure relates to a simplified adjustable stop and retainer for at least one of the drive control and steering levers for a skid steer vehicle which permits the operator to adjust a stopped position of the lever at the full forward speed position. The vehicle drive comprises hydraulic or hydrostatic motors on the opposite sides of the vehicle and by adjusting the full speed position of one control, the speed of the motor controlled by the one lever can be matched in speed to the motor controlled by the other lever. By this adjustment, an operator can assure that the skid steer vehicle will not tend to veer from a straight line when traveling forwardly at full speed. 
     Since the adjustment is easily accessible, the adjustment can be made easily during operations if any tendency to drift one way or the other is noted. Further, the retaining strip helps prevent the accidental movement of the stop screw due to vibrations that occur during the operation of the vehicle. 
     This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. The claimed subject matter is not limited to implementations that solve any or all disadvantages noted in the background. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a top view of a skid steer loader schematically showing the control lever and drive. 
         FIG. 2  is a fragmentary schematic side elevational sectional view showing a typical steering lever mounting on a bellcrank that pivots on a shaft, and including a stop for adjusting the position of the lever according to the disclosed embodiments. 
         FIG. 3  is a close up view of the stop screw and retaining strip. 
         FIG. 4  is an exploded view of the stop screw, nut, bracket and retaining strip. 
         FIG. 5  is a perspective top view showing the steering panel of the cab of a skid steer loader and the access opening for the adjustable stop. 
         FIG. 6  is a schematic perspective view of the adjustable stop of the disclosed embodiments. 
         FIG. 7  is a perspective view of a steering bracket assembly showing the mounting for the adjustable stop. 
     
    
    
     DETAILED DESCRIPTION 
     The use of a pair of control levers for controlling movement of skid steer loaders is well known.  FIGS. 1 and 2  show, respectively, a skid steer vehicle comprising a loader  80  as shown and described, having wheels driven in pairs, including the pair of left side wheels  9 A and the pair of right side wheels  9 B. The loader  80  has a frame  10  that supports an engine for power to drive a pump  11  for providing fluid under pressure to the controllable drive motors and other components. 
     The drive control lever or sticks  16 A and  16 B are pivotally mounted on shafts below the operator&#39;s or cab platform  12 , and extend into the cab. Each side of the loader is driven through a separate flow controlled, variable speed (swash plate) motor  30 A and  30 B. The speed of motors  30 A and  30 B is dependent upon the position of the respective steering levers. As can be seen, motor  30 A drives both of the wheels  9 A simultaneously and motor  30 B drives both wheels  9 B simultaneously. 
     In a neutral position of the levers  16 A and  16 B, the loader is stopped. Moving the levers  16 A and  16 B forward results in forward movement, with the speed of the controlled motor being proportional to the lever movement. When the levers  16 A and  16 B are both fully forward, maximum forward speed is achieved. The speed of the motors  30 A and  30 B should match each other to keep the loader traveling straight. 
     The schematic showing of  FIG. 2  is a fragmentary side view of a portion of the skid steer loader frame  10  that shows a front portion of platform  12  forming part of the frame, with an operator seat area  14  to the rear of the front portion of the platform. Control lever  16 B is shown schematically, and it extends into the operator&#39;s cab, and is moved forward and rearward from a neutral position, in order to drive the controlled motor to propel the loader forward or rearward. The neutral position of lever  16 B is substantially as shown in solid lines in  FIG. 2 . 
     The levers  16 A and  16 B also control the speed of the drive wheels on each side of the loader, and when going forwardly at the full forward position of the levers, it is important that the motors  30 A and  30 B are running at the same speed or else the loader will tend to “veer” or not run exactly straight. 
     Disclosed embodiments provide an adjustment of the full forward position of one control lever, so that it can be “tweaked” or otherwise adjusted to ensure that the drive speed of the motors on each side of the loader at full forward control lever stroke of both levers will be exactly the same. Both levers  16 A and  16 B can have the adjustable stop arrangement, if desired. 
     The lever  16 B shown in  FIG. 2  has an arm portion  18 , that is fastened to a saddle  23  which is part of bellcrank  20 . This bellcrank rotates about mounting shaft  21  that is supported on the frame  10 . The lever arm  18  is fastened to the saddle  23  with suitable U-bolts  22  and  24 . The lever  16 B pivots and rotates the bellcrank  20  about the axis of shaft  21  between the dotted line positions shown in  FIG. 2 . The solid line position of lever  16 B is the neutral position. The bellcrank  20 , as schematically shown will move a lever  26  that in turn is connected through a link  28  to pump/motor control  29  that adjusts a swash plate or variable speed drive pump/motor indicated at  30 B. The pump/motor control  29  also is standard, and the showing in  FIG. 2  is simplified. 
     As the steering lever  16 B is pushed forwardly, to achieve a desired forward speed, the bellcrank  20  rotates in a clockwise direction as illustrated in  FIG. 2 , so that the end of U-bolt  24  tends to move in an arc toward the inner side of the forward portion of panel  12 . 
     In the disclosed embodiments, an adjustment stop bracket  32  is fixed in position on the panel  12 , and has a projecting end flange  34  that has an adjustment nut  36  welded or otherwise attached on the lower surface thereof. Prior to welding or otherwise attaching the nut  34  to the lower surface of the flange  36 , the bracket  32  is in some embodiments painted. By painting the bracket  32  prior to assembly it enables the bracket to be more resilient to the elements. An adjustment screw  38  extends through the nut  36 , and when the screw is threaded, it will move in and out along its axis. 
     A rubber retaining strip  100  is placed on the screw  38  prior to the threading of the screw  38  into the bracket  32  and nut  34 . The rubber strip  100  has two holes or apertures,  102 ,  104  ( FIG. 4 ). Screw  38  is first pressed through hole  102 . Then, the screw  38  is threaded in place. After the screw is threaded in place, the rubber strip  100  is placed over bracket  32  and is attached to the bottom portion of screw  38 . This is achieved by placing the screw  38  through hole  104 . Thus, in the assembled condition, hole  102  contacts a first portion  38 - 1  of screw  38 , and hole  104  contacts a second portion  38 - 2  of screw  38 , and the retaining strip  100  interfaces with both screw  38  and bracket  32 .  FIGS. 3 and 4  are close up views of the retaining strip  100 . These figures illustrate the placement of strip  100  on the bracket  32 . 
     With the rubber strip  100  in place over the bracket  32 , the strip  100  imports a restraining force on the screw  38 . In some embodiments, this retaining force is caused by stretching. However, other methods of imparting this restraining force can be used. This restraining force provides a force on screw  38  that inhibits the rotation of the screw due to vibrations. These vibrations are commonly associated with the movement of the vehicle over terrain, or the simple idling of the engine. However, the strip  100  does not provide sufficient force to prevent the adjustment of screw  38 . In some embodiments the restraining strip  100  can be released from the stop screw prior to adjustment. This is achieved by taking the end associated with hole  104 , and sliding it off of the stop screw. This releases the pressure on the bracket  32  and screw  38 . 
     The size of the holes  102 ,  104  and the length of the strip  100  are determined by the properties of the rubber and the desired resistance to vibration. While strip  100  has been disclosed as being rubber, it can, in alternative embodiments, be made of other flexible materials. For example, it could be made of nylon or a flexible plastic. 
     The adjustment screw  38  is accessible through an opening  40  in the horizontal portion of platform  12 , from the interior of the operator&#39;s cab so that the screw  38  can moved in and out. 
     The end of the screw  38  aligns with a flat spot  42  on the top closed end of the U-bolt  24 , when the steering lever  16 B is pushed all the way forwardly as shown in dotted lines in  FIGS. 2  and in  FIG. 5 . The stop bolt  38  will provide a stop against the flat spot  42  of the U-bolt  24  and stop movement of the lever  16 B. The stop bolt  38  determines the pivoted position of the lever  16 B and the link  28 , and thus the position of the swash plate velocity control for the motor  30 B. The speed of rotation of the drive motor  30 B when the lever  16 B is stopped in full forward position can be adjusted. 
     By driving the loader at the full forward speed positions of the levers  16 A and  16 B, it can immediately be noted if the wheels on opposite sides of the loader are at equal speeds. If not, one or both of the levers can be changed slightly in its stopped position to change the output speed of the drive pump/motor  30 A or  30 B for the respective side of the loader. As shown, motor  30 B is controlled, and by adjusting the screw  38  and providing a new stopped position for the steering lever  16 B when it is in its full forward stroke, an adjusted full speed of the motor  16 B will result. 
       FIG. 5  is a schematic, fragmentary view showing the access opening  40  and the head of adjusted screw  38 . It is thus easily accessible to an operator. It should be noted that the levers  16 A and  16 B return to neutral when they are released. 
     In  FIG. 6 , the steering lever  16 B is shown fragmentarily, in relation to the platform  12 , and the stop bolt  38  is engaging the flat spot  42  on the U-bolt  24 . It can be seen in  FIG. 4  that the arm portion  18  of the steering lever  16 B is clamped in place on the bellcrank  20 . 
     In  FIG. 7 , a perspective view of the steering bracket assembly showing the mounting for the adjustable stop is provided. As can be seen in this perspective view, adjustment nut  36  is welded or otherwise attached to the sheet metal of steering bracket  32 . The adjustment screw  38  is shown extending through the nut  36  and retaining strip  100 . 
     Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.