Abstract:
A slide hammer for driving a probe into the ground includes a probe lifting and removal arrangement in which a slide hammer tube is pivoted away from the probe to function as a lever operating with a clutch arrangement to incrementally withdraw the probe from the ground. A biasing arrangement using a coil spring is operative to hold the anvil in a locked probe driving position, to facilitate release of the tube from the locking position for pivotal movement to the probe removal position, to bias a clutch disk to a release position with respect to the pin, to facilitate incremental lifting contact between the clutch disk and the pin, and to return the tube to a subsequent incremental lifting position.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention pertains to an apparatus for driving a long narrow probe into the ground to assist in the location of leaks in natural gas pipelines. The probes have a number of different names including needle bar, pin, searcher bar, and plunger bar. The bar which is typically a ½ inch-⅝ inch steel rod is driven into the ground using a slide hammer to a depth of about 3 feet or more. The needle or probe is then pulled out of the ground and the gas concentration in the hole is measured with a hand-held detector. By driving a number of holes and measuring the difference in gas concentration in each, utility personnel can determine the size and position of the leak more accurately and, therefore, minimize size and extent of an excavation needed to find and repair the leak. 
         [0002]    Slide hammer operation may be undertaken by utility workers and others many times during the day and the activity is known to cause repetitive stress injury. More recently, it has been determined that removing or pulling the probe from the ground is more damaging than the probe driving operation. Removing the tool by typical current methods requires lifting the 10-15 lb. hammer against the force of gravity and, in addition, the impact of the weight against the probe on retraction tends to compress the spine of the worker, significantly increasing the likelihood of injury. 
         [0003]    Probe pulling devices are known in the industry to eliminate the purely manual lift-to-remove technique. These devices are similar to a conventional fence post puller in which a long lever is pivoted on an axis close to a gripping jaw around the post that may be operated by hand or by foot. Utility workers do not favor these pullers because they are awkward and heavy and are difficult to carry along with the probe driver and gas analyzer. 
         [0004]    Recently activity has been devoted to the development of a combined needle or probe driver and remover but, to date, no such device has found any significant industry acceptance. 
       SUMMARY OF THE INVENTION 
       [0005]    In accordance with the present invention, a bar hole probe driver and remover are combined in a single tool that is simply operated and does not add significantly to the weight of a conventional slide hammer driver. The apparatus of the present invention utilizes a conventional bar hole probe driver construction in which an anvil is attached to the upper end of the probe and the anvil and probe are received in a slide hammer tube adapted to strike the anvil and drive the probe into the ground in response to axial downward driving movement applied manually to the hammer. A unique alignment, release and removal apparatus includes a housing that is pivotally attached to the lower end of the slide hammer tube and has an open interior for slidably receiving the pin. The open interior of the housing contains a biasing spring arrangement that is operative to provide several significant functions, namely, to hold the anvil in the lower end of the slide hammer tube to lock and align the tube and the housing interior in a probe driving position; to release the tube from locked alignment with the housing permitting pivotal movement of the tube to a probe removal position relative to the housing (and releasing the housing to drop with the tube to the ground); to bias a clutch disk in the housing to a release position with respect to the pin; to facilitate incremental lifting contact between a tube extension bracket and the clutch disk to cock the disk into lifting engagement with the pin; and to return the tube to a next lifting contact position. 
         [0006]    In a preferred embodiment, the housing interior is generally cylindrical and coaxial with the slide hammer tube in the probe driving position. The biasing spring arrangement preferably comprises a coil spring that surrounds the probe and is retained in the housing interior in a substantially uncompressed state in the probe driving position between a shoulder in the bottom of the housing and a closure arrangement at the top of the housing. The clutch disk comprises a bottom washer that is positioned between the housing bottom shoulder and the lower end of the coil spring. The closure arrangement includes a top washer on the upper end of the spring, a retainer ring that overlies the top washer, and a locking ring that engages the housing interior above the retainer ring. 
         [0007]    The tube extension bracket preferably comprises a lever bracket that extends axially and laterally away from the end of the slide hammer tube and has a tooth on a free opposite end adapted to engage the clutch disk. The pivotal attachment of the lever bracket to the tube includes a pair of clevis plates attached to the outside of the housing and defining therebetween a slot for the lever bracket. A horizontally disposed pivot pin attaches the lever bracket to the clevis plates and a vertical slot in the housing wall between the clevis plates provides an opening for the free end of the lever bracket to permit the tooth to engage the clutch disk in response to lever bracket rotation. 
         [0008]    In a presently preferred embodiment, the shoulder at the bottom of the housing is frustoconical and converges downwardly to define a vertical bore for maintaining alignment of the pin. The complete biasing arrangement includes the bottom washer (or clutch disk) resting on the shoulder, the coil spring, and an anvil stop which prevents the probe and anvil from dropping vertically through the housing. Or, stated another way, the anvil stop limits upward movement of the housing with respect to the pin. The anvil stop may comprise a top washer identical to the bottom washer. The spring biasing arrangement is completed with a retainer ring above the top washer seated on a housing top shoulder that is defined by a counter bore in the housing, and a snap ring that is seated in a groove in the housing above the retainer ring. 
         [0009]    Instead of a single clutch disk washer, a plurality of stacked washers may be used. The apparatus is quickly and easily converted from the probe driving position to the probe removing position. In the driving position with the upper end of the anvil extending into the bottom end of the slide hammer tube, upward lifting of the housing against the force holding the probe in the ground will cause the housing to move vertically upwardly causing the anvil to be withdrawn from the slide hammer tube. The tube may then pivot with the lever bracket away from the anvil and down toward the probe removing position. In this position, the entire assembly of the housing, lever bracket and tube is released to slide downwardly along the probe to the ground. With downward rotation of the bracket and tube, the tooth at the end of the pivot bracket moves through the slot in the housing and into engagement with the clutch disk upon continued downward rotation of the lever bracket and tube. Normally, the clutch disk is biased to a contact release position with respect to the probe but, when it is desired to remove the probe from the ground, the lever bracket tooth is caused to engage and cock the clutch disk into engagement with the pin. Continued downward rotation of the lever bracket and tube causes the engaged clutch to pull the probe out of the ground by an incremental amount. Release of the lever bracket will cause the bias spring to return the toothed end of the lever bracket downwardly, releasing the engagement of the disk with the pin, and returning the lever bracket and tube to an upper lifting contact position. 
         [0010]    When the probe has been pulled vertically upward to a position where it can be easily removed manually from the hole, a lever bracket and tube are pivoted upwardly until the tube end engages a chamfered surface on the upper end of the anvil, permitting the end of the tube to override the anvil and press it downwardly against the bias of the coil spring. After the tube has cleared the anvil, the spring returns the anvil to its uppermost locking position within the lower end of the tube. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a perspective view of a probe driving and removing apparatus of the present invention. 
           [0012]      FIG. 2  is an exploded view of the apparatus shown in  FIG. 1 . 
           [0013]      FIG. 3  is a sectional view of the apparatus shown in  FIG. 2  in the operative driving position. 
           [0014]      FIG. 4  is a sectional view, similar to  FIG. 3 , showing the initial conversion of the apparatus from the probe driving position to the probe removing position. 
           [0015]      FIG. 5  is a sectional side elevation of the apparatus shown in  FIG. 4  rotated to its operative position for probe removal. 
           [0016]      FIGS. 6 and 7  are enlarged sectional details showing incremental movement of the probe in the probe removal stroke of the apparatus. 
           [0017]      FIG. 8  is a perspective view of an alternate embodiment of the apparatus shown in  FIG. 1 . 
           [0018]      FIG. 9  is a sectional elevation through the embodiment of the apparatus shown in  FIG. 8 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0019]    In  FIG. 1 , there is shown an assembly of a probe driving and removing apparatus  10  of the present invention. The apparatus is used to drive a so-called needle bar or probe  11  into the ground and then to withdraw the probe to permit the concentration of leaking gas in the hole to be determined. Referring also to  FIG. 2 , the probe has a solid steel body and may be, for example, ⅝ inch (15 mm) in diameter. A larger diameter anvil  12  is attached to the top of the probe and is received in a cylindrical tube  13  of the slide hammer. The probe and anvil  12  slide freely in the tube  13 , but the top end of the tube is closed by an end cap  14 . In use, the operator raises the tube and cap vertically along the anvil and probe and then brings it vertically downwardly causing the cap  14  to strike the anvil  12  to drive the bottom end of the probe  11  into the ground. Repeated hammering strokes are necessary to drive the probe to an adequate depth, e.g. 3 feet (about 1 m) deep. Typically, some length of the probe  11  will remain above the level of the ground (see  FIG. 5 ). 
         [0020]    The foregoing describes the construction and use of a conventional slide hammer. However, the present invention is directed to an improved apparatus for removing the probe from the hole in a manner that minimizes operator strain, fatigue and potential injury. 
         [0021]    The lower end of the slide hammer tube  13  has a lever bracket  15  welded to the outside of the tube. The lever bracket  15  extends laterally and downwardly from the lower end of the tube  13  and is pivotally connected to a lower lifter housing  17  with a horizontally disposed pivot pin  16 . 
         [0022]    Referring also to  FIGS. 3 and 4 , the lifter housing  17  has a generally cylindrical inner wall  18  for mounting a biasing arrangement that provides several significant functions. In the probe driving position of  FIG. 3 , the lifter housing  17  is aligned with the slide hammer tube  13  such that the tube  13 , probe  11  and cylindrical inner wall  18  of the housing are coaxially aligned. The biasing arrangement  20  is contained in the housing  17 . The housing includes a shoulder  21  at the bottom of the cylindrical inner wall  18  which, in the embodiment shown, is frustoconical in shape, but it could be flat as well. The shoulder  21  converges downwardly and defines at its lower end a vertical bore  22  to help maintain alignment of the pin  16  as it passes therethrough. The biasing arrangement comprises, from the lower shoulder  21  upwardly, a lower washer  23 , supported on the shoulder  21  and having a circular axial opening slightly larger than the diameter of the pin  16 , such that in the probe driving position shown in  FIG. 3 , the washer is horizontal and probe movement therethrough is unrestricted. The biasing spring, in the form of a coil spring  25 , rests atop the lower washer  23  and surrounds the probe on the interior of the lifter housing  17 . An upper washer  26 , which is preferably identical to the lower washer  23 , rests on top of the upper end of the coil spring  25 . A retainer ring  27  is seated on an upper shoulder  28  defined by a counterbore  30  at the upper end of the cylindrical inner wall  18  of the housing  17 . The biasing arrangement is held within the housing by a snap ring  31  held in a groove  32  at the upper end of the counter bore  30 . 
         [0023]    The probe  11  and anvil  12  can slide freely within the slide hammer tube  13  between an upper position in which the anvil  12  is engaged by the end cap  14  and a lowermost position in which the anvil  12  passes partially through the center hole  29  in the retainer ring  27  and engages and is supported on the upper washer  26 . In this position, shown in  FIG. 3 , the anvil  12  protrudes upwardly past the upper end of the housing  17  and a short distance into the bottom end of the tube  13 . This is the aligned driving position in which the tube  13  and housing  17  slide together in reciprocal movement for driving the probe and anvil  11 ,  12 . Thus, at the upper end of the driving stroke of the tube/housing assembly  13 ,  17 , the anvil  12  is resting on and supported by the upper washer  26 . In the lowermost position, where probe driving contact occurs, the anvil  12  is engaged by the cap  14  at the upper end of the tube  13 . 
         [0024]    When the probe has been driven a sufficient distance into the ground, the tube  13  and attached lever bracket  15  are pivoted on pivot pin  16  to rotate away from the lifter housing  17  to a probe removal position, as will be explained in greater detail below. Initially, however, the slide hammer tube  13  must be released from alignment with the housing and locking engagement by the anvil  12 . To unlock the tube  13 , the operator slides the interconnected tube and housing vertically upwardly until the anvil  12  engages the upper washer  26 . A slight continued upward motion against the bias of the coil spring  25  causes the spring to compress and the anvil  12  to be withdrawn from the tube  13  as shown in  FIG. 4 , whereby the tube and lever bracket  15  are free to pivot away from the lifter housing  17 . Once the tube has been separated from the housing, and pivoted away from the anvil  12  and probe  11 , housing  17 , along with the lever bracket and tube, are free to slide downwardly along the probe and onto the surface of the ground. This establishes the probe removing position of the tool shown in  FIG. 5 . 
         [0025]    The lower end of the lever bracket  15 , opposite the bracket connection to the tube, is provided with a tooth  33 . The lever bracket is pivotally mounted on a pivot pin  16  between a pair of parallel clevis plates  34  that are attached to the outside of the lifter housing  17 . The clevis plates may be reinforced with gussets  35  welded to the housing and to the clevis plates  34 . Between the clevis plates, the housing is provided with a narrow vertical slot  36  which is open to the interior of the housing and is just wide enough to receive the end of the lever bracket and tooth  33  as the lever bracket and tube are pivoted downwardly. As the tooth  33  enters the slot  36 , it engages one edge of the lower washer  23  (see  FIG. 6 ) and, with continued rotation, cocks the washer out of its coaxial alignment with the probe  11  and causing the inner peripheral edge of the washer to engage and grip the probe (see  FIG. 7 ). Upward rotation of the tooth in engagement with the washer  23  causes the probe to be lifted vertically and incrementally out of the ground and upwardly within the interior of the housing  17 . The incremental movement of the lower washer and captured probe may be in the order of 1-1.5 inches (25-38 mm). This probe removing motion is easily and comfortably applied by the foot or the hand of the operator, the length of the tube  13  providing a good mechanical advantage. When the incremental stroke is complete and the operator releases the pressure on the tube  13 , the bias of the coil spring  25  realigns the lower washer  23  so it can slide downwardly in the interior  18  of the housing  17  and into engagement with shoulder  21 . This return biasing force also applies a downward force on the lever bracket tooth  33  to assist the upward pivotal return of the bracket and attached tube  13  into a position ready for downward movement for the next incremental removal stroke. The process is repeated, with the peripheral interior edge of the washer engaging the probe in the manner of a clutch mechanism, until the probe has been pulled vertically upwardly to a position where it can be easily removed from the hole. 
         [0026]    It should be noted that, although the washer  23  is shown as a common circular washer with a circular hole, other shapes of clutch disks could be used as well. For example, the outer edge of the disk could be square, rectangular, or some other shape, and the interior hole could be a shape other than round. Ordinary circular washers are, however, preferred. 
         [0027]    The same probe  11  may be used to form the next bore hole, but if necessary because of damage, the probe is easily withdrawn through the biasing arrangement and out of the lifter housing  17 . To prepare the apparatus for driving the probe into the next hole, the lever bracket  15  and attached tube  13  are pivoted upwardly around the pivot pin  16  until the lower edge of the tube  13  engages the upper end of the anvil  12  which is resting and retained on the upper washer  26 . The upper end of the anvil  12  is provided with a chamfer  37  that assists in causing the tube end to override the anvil whereupon the upward bias of the coil spring  25  pushes the anvil  12  into the lower end of the tube to the aligned and locked probe driving position of  FIG. 3 . 
         [0028]    For servicing and maintenance, the biasing arrangement  20  is readily accessed. After the snap ring  31  is removed, all of the remaining components of the biasing arrangement may be easily slid upwardly out of the lifter housing  17 . If the lower washer becomes worn, it can be easily replaced. If the upper washer  26  is identical to the lower washer, their positions may be switched to, in effect, provide the clutch arrangement with a new washer. Also, a plurality of stacked lower washers  23  can also be used in which case the clutching force of the washers may be distributed and wear reduced considerably. 
         [0029]    A modified embodiment of the apparatus  40  is shown in  FIGS. 8 and 9 . In this arrangement, the lever bracket  41  has a sleeve  42  that surrounds the slide hammer tube  43  and is secured thereto. In the extraction operation shown, the sleeve, which has a diameter that corresponds to the outside diameter of the lifter housing  44 , provides a weight distribution with more mass closer to the pivot. This permits the use of a lighter spring  25  to return the lever bracket and tube upwardly to the position for the next incremental down stroke. An handle  45  is incorporated into the lever bracket  41  to facilitate carrying. Also, the clevis plates  46  may be extended to define a lower ground-engaging flange  47 . The flange  47  provides an enlarged “foot print” so that during driving operation, there is better support for the housing  44 , particularly in soft or loose soils.