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RELATED CASES  
       [0001]    This application is based on provisional application No. 60/059,374 filed on Sep. 19, 1998. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates to construction equipment attachments, and, more particularly, to a new two-speed, shift-on-demand auger drive for drilling holes in the ground.  
           [0004]    2. Description of the Related Art  
           [0005]    Current auger drives, such as attached to booms, tractors, skid steers and the like, are used to drill holes and telephone post holes, by means of a hydraulic motor attached to an auger.  
           [0006]    Currently in the art there are two-speed drive units, which are manually shifted from between a low speed and a high speed while the hydraulic unit is turning. This function is called shift-on-the-fly.  
           [0007]    Such hydraulic motor is shifted by a signal line controlled by the operator. Typical usage of such a unit, is to start drilling at a high torque level and leave it at such speed until the auguring function is completed. Then, the operator shifts the device to high speed to spin dirt from the auger.  
           [0008]    What is needed in the art is a auguring drive system that may automatically shift between low and high speed drive, thereby have greater throughput.  
         SUMMARY OF THE INVENTION  
         [0009]    According to the present invention a hydraulic motor is provided, having a single inlet and single outlet for hydraulic power, which utilizes a pressure sensitive kick down valve to shift the hydraulic motor from one speed to another upon sensing a certain degree of pressure from the auguring function. The hydraulic motor is attached between a member such as a boom or frame of vehicle for easy transport, and the output end includes connection to an auger bit. Additionally, the two speed drive may operate in both the forward and reverse operating directions.  
           [0010]    An advantage of the present invention is that the pressure sensitive kick down valve utilized within the system, automatically senses the certain degree of pressure from the auguring rotating function. If the ground conditions are easily augured, the unit may not shift into the high torque mode, since it is not required. If drilling conditions require higher torque than the state the unit currently is, the unit will sense this through the hydraulic back pressure of the system and selectively operate the hydraulic motor in a higher torque mode. Such operation may also operate in the reverse rotating direction by means of a shuttle valve.  
           [0011]    Another advantage of the present invention is that the system will determine automatically if higher torque is needed. Production and throughput levels will increase simply because most ground conditions do not require high torque at all times while auguring.  
           [0012]    A further advantage of the invention is that, compared to known two-speed hydraulic auger systems, no additional plumbing is necessary to connect on operator speed select line.  
           [0013]    Yet another advantage of the present invention, is that it may easily be fitted to any existing utility/construction equipment that has adequate hydraulic pressure to operate the unit. No extensive plumbing or retrofitting is necessary for connecting the invention to the old transportation structure. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein:  
         [0015]    [0015]FIG. 1 is a side view of the present invention; and  
         [0016]    [0016]FIG. 2 is a schematic view of one form of the present invention. 
     
    
       [0017]    Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates one preferred embodiment of the invention, in one form, and such exemplification is not to be construed as limiting the scope of the invention in any manner.  
       DETAILED DESCRIPTION OF THE INVENTION  
       [0018]    Referring now to FIG. 1, the present invention of the two-speed shift-on-demand auger drive system  10  is shown connected to a member  12 , such as a boom or extension member of a utility or construction vehicle. Such vehicle normally provides a source of hydraulic pressure as by an auxiliary hydraulic system. As shown in FIG. 1, such vehicle would be equipped with a hydraulic supply line  14 , for supplying sufficient hydraulic power to the hydraulic auger drive system  10 . Also connected to boom  12  is a hydraulic fluid return line  16 , supplying the previously utilized hydraulic fluid back to the auxiliary hydraulic system. The hydraulic two-speed shift on demand system  10  utilizes a hydraulic motor  20  connected to the hydraulic supply line  14  and hydraulic fluid return line  16 . Motor  20  is connected by a swivel or gimbled mount to boom  12  such that in normal operations the output shaft of motor  20  is oriented perpendicular to ground level  24 .  
         [0019]    One example of motor  20  is that of a commercially available model, such as a model  51  two-speed hydraulic motor from Commercial Intertech, although others may be equivalently utilized. An auger bit  26  is attached to the output shaft  28  of motor  20 .  
         [0020]    The design of the above referenced motor and equivalent other types are such that, motor  20  may be operated at two speeds, one speed for relatively high speed with low torque, and the other speed, that of a relatively low speed with high torque characteristics.  
         [0021]    The present invention includes the use of a pressure sensitive kick down valve unit  30 , made from a combination of a motor speed change valve, normally sold with the above referenced motor  20 , and connected to the hydraulic supply line  14 , along with a hydraulic pressure sensor utilized to measure the hydraulic pressure within system  10 .  
         [0022]    In one form of the invention, pressure sensor unit  30  may directly or indirectly measure the pressure of input hydraulic supply line  14 . One type of pressure sensor utilized is that of a Hydra-Force KF10-30 kick down sequential interval pilot sensor, which may be connected to the motor speed change valve.  
         [0023]    [0023]FIG. 2 shows a schematic of one form of the present invention in which hydraulic oil may enter or exit via lines  14  and  16  through ports  38  and  39 . The entry port is switched for forward and reverse, motor rotation. Both ports  18  and  19  are connected by hoses  40  and  41  through a shuttle valve  51 . Shuttle valve  51  allows oil from port  38  and  39  with the highest pressure to enter the sensing chamber of the pressure sensing valve  45 . Shuttle valve  51  simultaneously blocks any flow to or from port  18  or  19  with the lower pressure.  
         [0024]    When the oil pressure in the sensing chamber of the pressure sensing valve  45  reaches a preset level (the factory level may be set at approximately 1500 psi), the pressure sensing valve  45  opens indicated port 1 to port 2 and the hydraulic oil is allowed to flow through hose  43  to a control port  20  with a motor shifting valve which changes the motor internal oil flow pattern to the high-torque/slow-speed configuration.  
         [0025]    When the pressure in the pressure sensing valve  45  falls below a second preset level (factory level set at approximately 150 psi), the oil flowing through the pressure sensing valve  45  from port 1 to port 2 is shut off and port 2 is connected to port 3. This permits a return spring in the motor shifting valve to move the valve spool back to the low-torque/high-speed position. Oil which is displaced when the valve spool returns, passes through pressure sensing valve  45  from port 2 to port 3 and thereon and into case drain system of motor  20 . Port 3 on pressure sensing valve  45  is connected by a line  46  to the case drain system port  48  on motor  20 .  
         [0026]    In operation, the pressure sensor unit  30  may be set to actuate the motor speed change valve at a preset level, such as 250 PSI, or any other selected pressure. As long as the hydraulic pressure stays below such preset level the motor will operate in the high speed level. If on a drilling condition where the hydraulic pressure rises, such pressure sensor unit  30  will determine that a higher hydraulic pressure is being applied, therefore a higher torque is needed to auger. At such time, pressure sensor unit  30  will switch motor  20  to drill in a higher torque, low speed state.  
         [0027]    System  10  thereby automatically determines whether or not high torque auguring is necessary. In most applications, hydraulic system  10  will attempt to maintain motor  20  in the high speed, low torque state. With such functionality, drilling and auguring throughput will increase due to the higher average speed.  
         [0028]    Because of the connection to the auxiliary hydraulic system of the attached vehicle, with only supply line  14  and return line  16 , the hydraulic system  10  for the present invention may be easily retrofitted to old equipment.  
         [0029]    While this invention has been described as having a preferred design, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.

Summary:
A hydraulic auger system having a hydraulic motor capable of two speed operation, the motor including an output shaft which may rotate and a connected auger. A pressure sensitive kick down valve unit is connected to the hydraulic motor, whereby the unit determines the speed state of said hydraulic motor, based on resistance to rotation of auger, auger speed, or sensed hydraulic pressure.