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CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. Provisional Patent Application No. 62/079,904 filed on Nov. 14, 2014, entitled “Powered Shingle Remover” and the entire contents of which is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to a tool for use in removing surface covering materials, such as roof shingles. 
       DESCRIPTION OF THE PRIOR ART 
       [0003]    Outdoor surfaces are exposed to weather conditions that vary around different times of the year. In many instances, these surfaces need to be covered to provide protection against the environment. 
         [0004]    One outdoor surface in particular need of protection is a roof. Roofs are used to protect the interior of a house and other structures from the external environment, and are subject to severe weather conditions. A roof typically has an external water repellent surface covering made from a material that provides a reasonable service life at a reasonable cost. One such covering in widespread use is a bitumen based shingle that can be applied to the roof structure in a simple and efficient manner. 
         [0005]    Shingles are formed from strips of material that are arranged in rows across a roof. The shingles are secured by nails to the underlying structure and subsequent rows are arranged to overlap the nails of the previous, lower, row. Shingles can be made from materials such as wood, plastic, composites, metal, fiber reinforced cement, or other materials with the required surface protecting qualities. 
         [0006]    However, these surface coverings have a limited lifespan, depending on the material used, and need to be replaced on a regular basis. This requires the shingle and the nail to be removed so a new layer of shingles may be secured to a clean, flat surface. 
         [0007]    Traditionally, shovels and forks have been used to remove a shingle by inserting a blade or tine beneath the lower edge of the shingle. The shingle may then be levered vertically away from the substrate to which it is secured to release the shingle. The leverage from the shovel or fork also ideally extracts the nails securing the shingles on the surface and thereby leaves the surface ready for the new shingle. 
         [0008]    However, such methods are cumbersome and require a great deal of energy to be expended. Moreover, the shingle itself may tear around the nail, particularly when the shingle has deteriorated with age, leaving the nail in the substrate. Further work is then needed to remove the remaining nails and debris. 
         [0009]    In order to reduce the manual labour involved, a number of powered shingle removal tools have been developed. Exemplary patents include U.S. Pat. No. 4,691,439, which a shovel-like device with a blade having slots to engage the body of a nail. The apparatus uses a piston to provide the motive force for removing the shingles. However, the device requires manual operation by inserting the blade into engagement with the nails and pivoting to remove the shingles. As the device needs to be carried at all times and requires a large amount of force to remove the nails it can be understood that it still requires significant manual labour to remove the shingles. 
         [0010]    U.S. Pat. No. 4,663,995 shows a device for removing material, especially roofing material. It consists of a baseplate assembly connected to a shaft member with a guide handle attached. The baseplate includes a blade with teeth capable of being lifted and a piston drive to lift the blade. Actuation of the blade is performed manually after the blade has been positioned. 
         [0011]    U.S. Pat. No. 6,467,377, and U.S. Pat. No. 6,128,979 similarly show manually operated shingle removal mechanisms using a reciprocating baseplate driven via a piston drive. 
         [0012]    U.S. Pat. No. 5,988,021, U.S. Pat. No. 8,056,444, U.S. Pat. No. 5,863,100, U.S. Pat. No. 7,401,861 U.S. Pat. No. 4,858,503, and application US 2012/0096990 similarly show piston powered shingle removers with a reciprocating blade to remove the shingles and with roller assembly to facilitate movement over the roof. However all of these systems require manual actuation of the shingle removal system. The user must move to one portion of the roof sliding under the shingles, then actuate the removal mechanism, remove the shingles, and then carry on to the next portion of the roof. 
         [0013]    U.S. Pat. No. 7,992,467 shows a shingle removal apparatus with a handle, stripper member, and a drive assembly with a lost motion mechanism. The stripper member moves reciprocally up and down using a crank arm connected to a powered drive assembly. However, in this device the crank mechanism is continuously engaged, thereby consuming significant compressed air, which is used as the source of energy. 
         [0014]    U.S. Pat. No. 7,520,197 shows a roofing material removal device. The device can be pneumatically powered and automatically triggered. The automatic trigger is activated by the user pushing the device forward causing a drive member to push back and come into contact with a plunger. Once activated, a rigid member on the same drive receives an impact from an activated piston. Once the piston impacts this member it pushes forward, and a pulley assembly causes the front blade to lift on a lever raising the roofing material. The mechanism for lifting the blade is very complex and because of the orientation of the blade and drive mechanism for the blade, creates recoil when in use. Not only is this tiring, but the recoil poses a potential safety hazard when used on a roof. 
         [0015]    It is therefore an object of the present invention to provide a shingle removing device that obviates or mitigates the above disadvantages. 
       SUMMARY OF THE INVENTION 
       [0016]    Accordingly, the present invention provides a device for the removal of surface covering materials. The device includes a head having a blade for insertion between the covering material and a substrate. The head is supported for movement across the substrate and the blade is moveable away from the substrate to lift the covering material from the substrate. The blade is moved by an actuator acting in a direction generally normal to the substrate. Operation of the actuator is controlled by a sensor moving with the blade between the covering and substrate and responsive to the force opposing such movement to actuate the actuator. 
         [0017]    Preferably, the sensor is carried by the blade and projects in advance of the head to determine the opposition to continued movement of the blade. 
         [0018]    As a further preference, the sensor is moveable relative to the blade and relative movement between the blade and sensor causes said actuator to lift said blade away from said substrate. 
         [0019]    In a preferred embodiment, the head is supported on wheels and a handle assembly extends from the head to permit manipulation of the head on the substrate. 
         [0020]    Preferably, the blade is pivotably mounted on the head and the actuator cause pivotal movement of the blade relative to the head. 
         [0021]    By positioning the actuator to act in a direction generally normal to the substrate, the forces applied to the covering are reacted by the substrate and do not require the lifting forces to be reacted the operator. The sensor is not subjected to the lifting forces, thereby allowing the sensor to react to the resistance to continued motion and providing a lifting force only when required. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings in which 
           [0023]      FIG. 1  is a perspective view of a shingle removal device; 
           [0024]      FIG. 2  is a side perspective view of the device of  FIG. 1 ; 
           [0025]      FIG. 3  is a bottom perspective view of the device of  FIG. 1 ; 
           [0026]      FIG. 4  is a top view of the device of  FIG. 1 ; 
           [0027]      FIG. 5  is a cross sectional view of the device on the line  5 - 5  of  FIG. 4 ; 
           [0028]      FIG. 6  is a cross sectional view of the device on the line  6 - 6  of  FIG. 4 ; 
           [0029]      FIG. 7A  is a cross sectional view of the device on the line  7 - 7  of  FIG. 4 , showing alternative configurations of a sensor and valve utilised in the control of the shingle removing device; 
           [0030]      FIG. 7B  is a further cross sectional view of the device on the line  7 - 7  of  FIG. 4 , showing alternative configurations of a sensor and valve utilised in the control of the shingle removing device; 
           [0031]      FIG. 7C  is a further cross sectional view of the device on the line  7 - 7  of  FIG. 4 , showing alternative configurations of a sensor and valve utilised in the control of the shingle removing device; 
           [0032]      FIG. 7D  is a further cross sectional view of the device on the line  7 - 7  of  FIG. 4 , showing alternative configurations of a sensor and valve utilised in the control of the shingle removing device; 
           [0033]      FIG. 7E  is a further cross sectional view of the device on the line  7 - 7  of  FIG. 4 , showing alternative configurations of a sensor and valve utilised in the control of the shingle removing device; 
           [0034]      FIG. 8  is a schematic representation of the pneumatic control system used in the device of  FIG. 1 ; AND 
           [0035]      FIG. 9  is a view similar to  FIG. 1  of an alternative embodiment of a shingle removal device. 
       
    
    
       [0036]    The features of the invention will become more apparent in the following detailed description in which reference is made to the appended drawings 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0037]    Referring initially to  FIGS. 1 and 2 , an exemplary embodiment of a device for removing a surface covering material from a substrate is shown. The device is referred to as a powered shingle remover  100 . The remover  100  comprises a handle assembly  102  connected to a housing referred to as operating head  112 . The handle assembly  102  includes an elongate shaft  104  with a linear, straight, section  106  terminating in a curved section  108 . The linear section  106  of the shaft transitions into the curved section  108  through a plurality of elbows  120  to define a generally “C” shape lying in a transverse plane. Situated on the linear straight section  106  is a stabilising handle  110 , whose position may be adjusted along the linear section  106  to suit the operator using the remover  100 . 
         [0038]    The handle assembly  102  terminates in a yoke  114  for primary control by the operator. A plurality of switches are located on the yoke  114  for access by the operator including a switch  116  for manual override to allow manual operation of the device  100 , and a latch  118  which controls a handle lock mechanism  220  to adjust the angle between the handle assembly  102  and the operating head  112 . 
         [0039]    The handle assembly  102  also includes an anchoring mechanism  200  which has an anchoring nail  202  slide-able within a boss  224 . The nail has an exposed nail head  226  and is naturally biased to have its nail head  226  project from the housing  224  by a spring. 
         [0040]    Referring to  FIG. 2 , the stabiliser handle  110  is situated on the straight portion  106  of the handle shaft  104  and includes a main body  204  which fits over the handle shaft  104  and is secured using a clamping screw  208 . The main body  204  is attached to a “D” shaped grip  206 , which projects generally orthogonal to the axis of the shaft  104 . 
         [0041]    The head  112  includes a pair of side plates  210  spaced apart laterally to define each respective side face of the head  112 . A central body  212  is positioned between the side plates  210  and covered by a top plate  214 . 
         [0042]    As seen more clearly in  FIGS. 2 and 5 , each of the side plates  210  has an aperture  216  near its respective top apex with the centres of the apertures  216  aligned on a transverse axis. The apertures  216  are dimensioned to receive a terminal portion  218  of the curved portion  108  of the shaft  104  and allow for the handle assembly  102  to rotate relative to the head  112 . The handle assembly  102  may be locked relative to the head  112  using a handle lock mechanism  220 , as seen more fully in  FIG. 6 . A notched plate  604  is carried by the terminal portion of the curved portion  108  adjacent to one of the side plates  210  and a spring loaded piston  600  biased to engage one of the notches. The piston  600  may be moved by air pressure to release the piston from the notch and allow relative movement of the handle and head. 
         [0043]    The head  112  is supported by a pair of wheels  232 , each of which is connected to a respective one of the side plates  210 . The wheels  232  are rotatably supported on an axles  222  secured to the side plates  210 , to facilitate movement of the head  112 . The side plates  210  project forwardly from the axles  222  and carry spring loaded lift fingers  520  at their forward end that assist in lifting shingles as the head is pushed beneath the shingles. The fingers  520  are located within the side plate  210  and biased to be in the upright position via a spring. Each side plate  210  also has a guide strip  528  at the front of the side plates  210  to act as wear strips for a blade assembly  300 . 
         [0044]    As shown in  FIGS. 3 and 5 , the head  112  includes a blade assembly  300  which is rotatably mounted to the side plates  210  by a shaft  501  supported at opposite ends on bearings  508 . The blade assembly  300  has a trunnion  306  which has a pair of forwardly projecting fingers  304 . Each of the fingers  304  supports a blade  500  on parallel links  302  that allow relative fore and aft movement between the fingers  304  and blade  500  but transmit lifting forces from the trunnion  306  to the blade  500 . The links  302  have pins  522 ,  524  at opposite ends to permit limited pivotal movement of the links  302 . The blade  500  extends between the side plates  210  and the forward edge of the blade  500  has a series of notches or teeth. The blade  500  is biased to a forward position relative to the trunnion by torsion springs (not shown) acting on the links  502  to provide a resistance to rearward movement. 
         [0045]    The trunnion  306  also has a centrally located rearwardly projecting tail  510  that engages an end of a piston rod  310 . The piston rod  310  is connected to a piston  512  ( FIG. 5 ) which is slidable in a cylinder  516  formed in the central body  212  and sealed by a top plate  214 . The piston  512  and cylinder  516  are components of a reciprocating pneumatic motor, indicated generally at  518 , the details of which are shown schematically in  FIG. 8 . 
         [0046]    The pneumatic motor  518  operates on similar principles to those of a pneumatic nailer used to drive nails in to a substrate at high velocity. The piston  512  subdivides the cylinder  516  in to a pair of chambers  520 ,  522 . An accumulator  524  is connected to the closed chamber  520  to store air expelled from the chamber  520  during movement of the piston  512 . Air flow to the chamber  522  is controlled by a pressure balanced check valve  526  having a valve member  530  that is slidable in an extension  528  of the cylinder  516 . Air pressure from a source, typically a compressor, is fed to both sides of the valve member  530  through conduits  532 ,  534 . A spring  536  biases the valve member  530  in to a closed position in which flow to the chamber  522  is prohibited. 
         [0047]    A two position control valve  538  regulates flow through the conduit  534  and is biased to a first position in which flow from the source to the valve member is permitted. The control valve  538  is moveable to a second position against the bias so that air in the conduit  534  is vented to atmosphere. Movement of the valve from the first to the second position is controlled by rod  540  that projects toward the blade  500 . 
         [0048]    The rod  540  is aligned laterally with a rearward one of the links  302  which has a boss  702  facing the rod  540 . 
         [0049]    In operation, the configuration of the remover is first adjusted to suit the particular operator. Referring to  FIGS. 1, 2, and 6  when the angle between the handle shaft  104  and base assembly  112  is desired to be adjusted, the brake switch  118  can be activated. Activation of the switch causes deactivation of the air supplied to the piston  600  from the lock fitting  314 . This disengages the lock  602  from a hole on the disc  604 . This disengagement allows the terminal portion  218  of the handle shaft  104  to rotate. When the desired angle between the handle shaft  104  and base assembly  112  is reached, the brake switch  118  can be released. Releasing the switch  118  reactivates the air supplied to the piston  600  and causes engagement between the lock  602  and the desired hole on the disc  604 . 
         [0050]    The shingle remover  100  is then positioned on the roof so the blade  500  can pass beneath one of the shingles. The second handle  110  can be gripped at the gripper  206  and easily lifted. The second handle  110  allows for a means to lift the device  100  from closer to its centre of mass making it easier to transport. The location of the second handle  110  on the straight section  106  of the handle shaft  104  can be adjusted by loosening the fastener  208  using a suitable tool. When the fastener  208  is loosened it allows for the main body  204  to slide on the straight section  106  of the handle shaft  104 . When the main body  206  is at the desired location the faster  208  can again be fastened, fastening the main body  204  at the desired location on the straight portion  106  of the handle shaft  104 . 
         [0051]    With the remover positioned on the roof and connected to a supply of compressed air, the operator manoeuvres the remover  100  by rolling it along the roof on the wheels  232 . The blade  500  is introduced between the substrate and the shingle and pushed forwardly to lift the shingle from the roof. The upper edge of side plates  210  and the fingers  520  lift the shingle to allow the body to be advanced. 
         [0052]    Initially the remover is conditioned as shown in  FIGS. 5 and 7   a  with the blade  500  biased forwardly and the piston  512  fully retracted in the cylinder  516 . In this position, the control valve  538  is in its first position so that air is supplied to opposite sides of valve member  530 . The bias of the spring  536  maintains the valve member  536  in a seated position and prevents air from entering the chamber  522 . As the device is pushed forward, the blade  500  is subjected to increased resistance, typically by engagement with a nail, and is forced rearwardly relative to the sideplates  210  against the bias of the spring. The links  302  permit the rearward movement and bring the boss  702  into engagement with the rod  540  and displace the rod, as seen in  FIG. 7 b   . The rod  540  acts as a sensor to detect the rearward movement of the blade  500  and operates on the control valve  538  to move it to the second position and vent one side of the valve member  536  to atmosphere. The valve member  536  is unbalanced as air pressure acts on one side only and is moved off its seat to supply pressure to the chamber  522  to act on the piston  512 . Air in the chamber  520  is expelled in to the accumulator  524  to allow movement of the piston  512  in the cylinder  516 . 
         [0053]    The piston  512  moves downwardly in the cylinder  516  and acts on the tail  510  of the trunnion to cause it to rotate on the shaft  501 . As the trunnion rotates, it lifts the blade  500  through the links  302  and lifts the nail from the substrate as seen in  FIG. 7 c   . The vertical forces are of course taken by the wheels  232  acting on the substrate. The elongate side plates  210  stabilise the head  112  as the lifting force is applied to enhance the lifting forces applied. 
         [0054]    It will be noted that the boss  702  is moved away from the rod  540  as the blade is lifted, allowing the control valve  538  to return to its initial first position. The vent line is closed and the pressure on the valve member  536  balanced so that the valve member is again seated. Air stored in the accumulator  524  returns the piston  512  to its retracted position and allows the trunnion to return. The load is removed from the blade  500  in part through the operation of the fingers  520 , which hold the removed shingle away from the substrate. With the load taken on the fingers  520 , the nail is held above the substrate and the blade can move forward under the bias of the springs, as seen in  FIG. 7 d   . Once the blade is returned the device enters the configuration shown in  FIG. 7 e   , it can again be advanced to remove additional nails and strip the shingles from the roof. 
         [0055]    As seen in  FIGS. 1, 2, and 3 , the curved portion of the handle allows for no obstruction for the shingles as they move atop the base assembly  112 . Due to the handle shaft  104  being attached from the side, the shingles can slide above the base assembly  112  and land behind it, leaving the shingles behind as the device  100  continues operating on its set path. This in turn allows for a more systematic method for future cleaning and collection of the shingles. 
         [0056]    If the operator wishes to manually operate and cause the lifting of the blade mechanism, the manual override switch  116  can be used. When the manual override switch  116  is activated it acts on the rod  540  to move the control valve  538  to the second position and cause the piston  512  to move down vertically and perform the shingle removal operation previously described. 
         [0057]    Referring to  FIGS. 2 and 3 , when it is desired to secure the device  100  on a surface such as a roof, the anchoring mechanism  200  on the end handle assembly  102  can be utilized. First, the angle between the handle shaft  104  and the base assembly  112  can be adjusted such that the anchoring nail  202  is perpendicular or nearly perpendicular to the surface. The user then strikes the nail head  226  with a tool such as a hammer, causing the anchoring nail  202  to slide within the housing  224  and be driven into the surface. The anchoring nail  202  can then pulled upon using a tool such as hammer to disengage from the surface. When secured on the surface the anchoring nail  202  inhibits any movement of the device  100 . This is particularly advantageous when the device  100  is being used on a sloped surface, such as a roof. 
         [0058]    It can be appreciated that though the specification provided details the use of the device  100  to remove shingles on roofs, it can be utilized on any other surface to remove a surface covering material, such as floor tiles, in the same method of a powered material remover. 
         [0059]    The head  112  can be configured to carry different widths of blade  500  as shown in  FIG. 9 . As can be seen in  FIG. 9 , the blade  500  is wider than the spacing between the side plates  210 . Outriggers  900  and supported on the side plates  210  and support the lateral ends of the blade  500 . Fingers  520  are located on the outriggers  900  and have a bar  902  extending between them to provide support across the width of the blade for the removed shingle.

Summary:
A device used to remove surface covering materials such as shingles. The device is comprised of an end handle having a plurality of switches and an anchoring mechanism, a handle shaft with a straight and curved portion, a secondary handle, and a base assembly. The anchoring mechanism can be used to secure the device to its work surface. The base assembly provides the mechanisms to automate the removal of shingles or other surface covering materials fastened using fasteners such as nails. The base assembly includes a blade assembly, a rotary support, a lever, a piston assembly, and a switch valve. The switch valve controls the routing of the fluid supply connected to the device. The device is powered by a supply of air or other fluid from a source such as a compressor.