Abstract:
There is described an improved device for dispensing substance from a cartridge. The device includes a retaining mechanism for retaining a substance containing cartridge. The device further includes a telescoping plunger assembly, the assembly including at least a frontmost member, a rearmost member and at least one intervening member which can be in the nature of a turnbuckle. At least a portion of the plunger assembly is connected to the base. A motor is provided for rotating the turnbuckle of the telescoping plunger assembly, and there is also a fast rewinder comprising a turnbuckle splitter whereby the turnbuckle splits longitudinally into two halves. The device additionally includes a plunger biassing mechanism whereby the telescoping plunger assembly can be manually compacted against the resistive force of two or more plunger biassing springs.

Description:
BACKGROUND OF THE INVENTION 
   A. The Field of Invention 
   The present invention relates to a device for dispensing substance from a cartridge and more particularly to a compact motorized device for dispensing substance from a cartridge with a quick rewind feature. 
   B. A Description of the Prior Art 
   Mechanical caulking guns are well known in the field for use in dispensing material from a cartridge. These substance containing cartridges are well known in the construction industry and are generally cylindrical in shape, with a plastic delivery cone attached to one end of the cylinder and a flat, metal, disc-shaped base seal at the other. The disc-shaped base seal is of the same diameter as the cylinder so it may freely slide within the cylinder. When the plastic delivery cone is sliced open at its tip, the front seal behind the delivery cone is pierced, and the disc-shaped base seal is pushed within the cylinder towards the delivery cone, the substance within the cylinder is emitted from the delivery cone. 
   Currently these cartridges are used with mechanical devices, known as guns, which apply pressure to the disc-shaped base seal at the rear of the cartridge held within the gun. The most widely available guns consist of a holding receptacle for the cartridge, an integrated rod and plunger, and a ratchet mechanism whereby the rod and plunger are advanced though a hand operated lever. Pressure is applied to the disc-shaped base seal of the cartridge through the integrated rod and plunger which is activated in response to the pumping of a trigger on the gun. These mechanical guns can be awkward to use since, quite often, they are used to apply material to a hard to reach place. In such an instance, it is hard for the person using the gun to hold the gun steady while pumping the trigger with his index finger. With repeated use of such a mechanical device, one&#39;s hand will quickly become fatigued. The overall configuration of the mechanical gun when it is holding a cartridge is at least twice as long as the cartridge with the trigger midway along the length. The configuration of the conventional gun presents a number of ergonomic problems. Firstly, the rearward extension of the rod over the operator&#39;s hand can interfere with the operator&#39;s arm movement. Secondly, the excessive overall length of the mechanical gun presents positional problems in confined work spaces. Thirdly, the hand power required leads to arm fatigue and resulting loss of fine control over delivery of the contents of the cartridge. Lastly, at the end of the application of a bead of substance from the cartridge, bead overflow occurs which can only be prevented by the operator manually retracting the ratchet drive. Manual retracting of the ratchet drive makes control over the termination of substance delivery inconsistent and difficult to accomplish. 
   In the past, attempts have been made to design motorized substance delivery guns, however, these attempts have not cured the problem of having the rod protruding from the back of the loaded gun. In fact, many attempts at motorized devices for dispensing substance from a cartridge have created new problems relating chiefly to the added weight of the motorized unit, but also resulting from the cumbersome method by which the motorized mechanism had to be rewound once substance was delivered from the cone. 
   OBJECTIVES OF THE INVENTION 
   The primary objective of this invention is to address the ergonomic drawbacks of motorized and mechanical guns presently on the market and previously discussed by utilizing a telescoping plunger assembly which is able to expand in a linear direction from a compacted state to dispense material from a cartridge. A second objective is to provide a motorized drive mechanism with an automatic reversing mechanism to minimize overflow of substance when an operator stops the motorized mechanism through both a mechanical means when the motorized mechanism is an external motor and through a reversal of the motor itself when the motorized mechanism is an internal motor. A third objective is to provide a fast rewind mechanism to rapidly and automatically reset the plunger mechanism when a new cartridge is inserted into the invention. A fourth objective is to take advantage of lightweight materials to achieve a lightweight product which may be produced economically. A fifth objective is to provide accessories for operator convenience such as a delivery cone tip cutter, cartridge front seal piercing rod, bead application guides, and nipples which attach to the delivery cone which act as guides in shaping the bead as it flows out of the delivery cone. 
   SUMMARY OF THE INVENTION 
   According to the present invention, there is provided, a device for dispensing substance from a cartridge comprising: a retaining means for retaining a substance containing cartridge; a telescoping plunger assembly made up of a plurality of interconnecting members; a drive train means for driving said telescoping plunger assembly; and, a base to which at least one of the interconnecting members is fixed. 
   In its contracted state, the plurality of interconnecting members rest one within each other. Once the drive train means is actuated, the interconnecting members telescope along the longitudinal axis of the telescoping plunger assembly in a direction away from the point to which at least one of the interconnecting members is fixed to the base, thereby expanding the length of the telescoping plunger assembly. As the telescoping plunger assembly expands, the plunger head at the terminus of telescoping plunger assembly comes in contact with the base seal at the rear end of a cartridge that is held within the device by the retaining means, forcing substance to be emitted from the cartridge. 
   There are several methods by which drive train means can drive telescoping plunger assembly. Drive train means can force hydraulic fluid into the interconnecting members of telescoping plunger assembly, thereby causing the assembly to expand. While this method of driving telescoping plunger assembly works, the weight of the hydraulic fluid and the pumps necessary to inject and withdraw the fluid from the telescoping plunger assembly mean that this is not the best method of driving telescoping plunger assembly. 
   A better method involves a telescoping plunger assembly consisting of a plurality of threaded, at least partially hollowed out, members, each of which can be withdrawn into or upon an adjacent member when one of said members is rotated by the drive train means. In order for this better method for driving telescoping plunger assembly to work, however, the member (or members—for ease of description, the singular will be used, bearing in mind that there can be a plurality of non-rotating members) that is not driven by the drive train means must be fixed to the base so it does not rotate, but is still allowed to move along the length of telescoping plunger assembly as the threads on the rotating member interact with the threads on the non-rotating member. In this better method, the non-rotating member is fixed to the base by at least one stabilization rod that runs parallel to the length axis of the telescoping plunger assembly upon which the non-rotating member is free to slide. However, the disadvantage of this better method is that a great deal of torque is placed upon at least one stabilization rod. In order to properly stabilize the non-rotating member, a plurality of stabilization rods must be used, or an extremely strong stabilization rod must be used, all of which increases the weight of the device. The disadvantage is exacerbated in the case where there is a plurality of non-rotating members, each of which has to be stabilized. 
   In a more preferred embodiment for the present invention, the telescoping plunger assembly again consists of a plurality of threaded, at least partially hollowed out, members each of which can be withdrawn into or upon an adjacent member when one of said members is rotated, additionally there being at least a frontmost member, a rearmost member and at least one intervening member, wherein at least one of the intervening members is a turnbuckle which is rotated by drive train means. 

   
     DESCRIPTION OF THE DRAWINGS 
     Preferred embodiments of the present invention will be further described with the aid of the following drawings in which: 
       FIG. 1  is a perspective view, of the embodiment of the present device for dispensing substance from a cartridge wherein the device is powered by a reversible drill. 
       FIG. 2  is a perspective view of the retaining cap and canister which are seen towards the front of the device of  FIG. 1 . 
       FIG. 3  is a perspective view, partially cut away, showing details of the attachment of canister to ring of the present device. 
       FIG. 4  is a perspective view, partially in phantom, of the present device showing the front rod, rear rod, turnbuckle, hub, fixation nut and (partially in phantom) the transmission housing with slot. 
       FIG. 5  is a perspective view, with a longitudinal section removed, showing the front rod, rear rod, key, alignment cage and cap of the transmission housing of the present device. 
       FIG. 6  is a sectioned perspective view showing detail of the turnbuckle, front and rear rods and the keyway path of the present device. 
       FIG. 7  is a sectioned perspective view showing detail of the upper half of the turnbuckle, with cam followers, related cam slots, alignment cage and hub drive pin of the present device. 
       FIG. 8  is a sectioned perspective view showing detail of the upper half of the turnbuckle, with alignment cage and associated drive pin of the present device. 
       FIG. 9  is a sectioned perspective view showing detail of the present device, namely, the drive assembly with the turnbuckle halves in the engaged position and front and rear rods compacted, showing the positioning of cams and cam followers. Canister and transmission housing have been removed to reveal underlying detail. 
       FIG. 10  is a sectioned perspective view showing detail of the present device, namely, the drive assembly with the turnbuckle halves in the disengaged position and front and rear rods fully expanded, showing the positioning of cams and cam followers. Canister and transmission housing have been removed to reveal underlying detail. 
       FIG. 11  is a cross-sectional, front elevational view showing the brake actuator mechanism, transmission frame, transmission housing and telescoping plunger assembly of the present device. 
       FIG. 12  is an exploded perspective view, partially in phantom, showing the telescoping plunger assembly, turnbuckle, alignment cage and drive hub of the present device. 
       FIG. 13  is an exploded perspective view, partially in phantom, showing primary spur gear reduction unit, secondary gear reduction unit, driveshaft, drive hub and final gear of the present device. 
       FIG. 14  is a circuit diagram showing a passive backfeed circuit to reverse the direction of rotation of the drive hub when an internal motor for driving the device is turned off. 
       FIG. 15  is a circuit diagram showing an active backfeed circuit to reverse the direction of rotation of the drive hub when an internal motor for driving the device is turned off. 
       FIG. 16  is a side elevational view, partially in phantom, showing the telescoping plunger assembly, biasing spring means, the drive hub, fixation nut and the transmission housing of the present device when the telescoping plunger assembly is compacted. 
       FIG. 17  is a side elevational view, partially in phantom, showing the telescoping plunger assembly, biasing spring means, the drive hub and the transmission housing of the present device when the telescoping plunger assembly is expanded. 
       FIG. 18  is a perspective view showing a guide mount for the present device and a joist guide fitted to the guide mount. 
       FIG. 19  is a perspective view of a seam guide, and seam guide when fitted to the guide mount shown in  FIG. 18 . 
       FIG. 20  is a perspective view of an adjustable guide fitted to the guide mount. 
       FIG. 21  is a perspective view of the reverse side of the adjustable guide for the present device shown in  FIG. 20 . 
       FIG. 22  is a perspective view showing the detail of a tip cutter and a puncture rod for the present device, when not fitted to the present device. 
       FIG. 23  is a side elevational view showing detail of the threads of the front and rear rods of the present device, with the majority of the length of the turnbuckle being cut away. 
       FIGS. 24   a, b  and  c  are perspective views of a variety of detachable nipples for use with the present device. 
       FIGS. 25   a, b  and  c  are expanded views of the tips of the nipples shown in  FIGS. 24   a, b  and  c.    
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   The front end of a device  1  for dispensing substance from a cartridge, which is in the nature of a caulking gun and will sometimes be referred to hereinafter as such for convenience, is dimensioned to receive a substance containing cartridge  10  through a hollow cylindrical canister  12 . Cartridges such as cartridge  10  are presently available in the building supply industry for substances such as caulking, sealants, glue and lubricants. Cartridge  10  is a standard stock item with a delivery cone  14  protruding from one end and a base seal  16  at its other end. The diameter of base seal  16  matches that of the interior of cartridge  10 . When force is applied to the centre of base seal  16 , it will slide along the interior of cartridge  10 , causing the contents of cartridge  10  to be expelled from delivery cone  14 . 
   Force is applied to base seal  16  through plunger head  18 , which can be seen in  FIG. 4 . Cartridge  10  is held in gun  1  by retaining means generally identified by reference numeral  20 . Cartridge  10 , once it is placed in the front end of canister  12 , is retained in canister  12  at its front end by retaining means  20  including retaining cap  22 . The cap  22  is disk shaped with a groove  24  cut in to it so it can be positioned over delivery cone  14 . Two perpendicular tongues  26  and  28 , which are curved to match the radius of cap  22  and the wall of canister  12 , are attached to cap  22  on either side of groove  24 . Tongues  26  and  28  attach to canister pivots  30  and  32 . The tongues  26  and  28  are flexible and the space between them is equal to the outside diameter of canister  12 . End  34  of canister  12  is cut at approximately forty-five degrees toward its upper region  36  such that cap  22  can be pivoted about canister pivots  30  and  32  over the upper region  36 . As the radius of curvature in tongues  26  and  28  matches the radius of curve of canister  12 , cap  22  will tend to snap into place when it is swung over upper region of end  36  to rest up flush against end  34 . 
   The rear portion  38  of canister  12  is fluted with a number of flutes  40  cut along the length of the rear portion  38  of canister  12 . Raised annular ring  42  is positioned to fit into annular groove  44  positioned in the interior of ring  46 . This arrangement of annular ring  42  sitting in annular groove  44  allows for an axial lock of canister  12  in ring  46  while permitting relative rotation of canister  12  within ring  46 . Circumferential compression of the rear portion  38  of canister  12  will disengage annular ring  42  from annular groove  44  in ring  46 , allowing for the removal of canister  12  from the remainder of gun  1  and access to the workings of the gun for repair and maintenance work. Canister  12  can be reattached to the device for dispensing substance from a cartridge  1  at the front end of ring  46  by circumferentially compressing the rear portion  38  of the canister, positioning annular ring  42  adjacent to annular groove  44 , and releasing compression allowing annular ring  42  to expand into annular groove  44 . Compression of the rear portion of canister  12  may be facilitated by squeezing together handles  37 ,  39  on C-clamp  41 , which is positioned over the rear end of canister  12 . Flutes  40  may also be equipped with outwardly directed barbs  48 , which can catch on an inward facing lip  50  on annular groove  44  should a stronger grip surface between the retaining means  20  and the transmission housing  52  (via ring  46 ) be necessary. Rotation of canister  12  allows an operator to position guide mount  60  while holding the remainder of gun  1  stationary. 
   Ring  46  is attached at its rear end to transmission housing  52 . Transmission housing  52  consists of a thin cylindrical shell, closed at its rearmost end with cap  54 . Slot  56 , which is seen in  FIG. 4 , runs along the length of the underside of transmission housing  52 . Ring  46  is mounted on transmission frame  58  by way of axial grooves  62 ,  64  as shown in  FIG. 11  which accept the flared edges  66 ,  68  of transmission frame members  70 ,  72 . Ring  46 , together with attached canister  12  and transmission housing  52 , is therefore free to slide along the length of transmission frame  58 . Transmission housing  52  is able to slide over drive assembly  74  through slot  56  seen in  FIGS. 16 and 17  in the underside of transmission housing  52 . 
   Plunger head  18  is moved forwards and backwards along the length of gun  1  via telescoping plunger assembly generally designated by reference numeral  76 . Telescoping plunger assembly  76  consists of a plurality of interconnecting elements, at least one of which is able to be withdrawn into or extended from a recess in the next adjacent element. When all the elements are withdrawn into the recesses in the next adjacent element, telescoping plunger assembly  76  is fully compacted. When all the elements are extended from the recesses in the next adjacent element, telescoping plunger assembly  76  is fully extended. In the preferred embodiment, the major components of telescoping plunger assembly  76  are front rod  78 , rear rod  80  and intermediate turnbuckle  82 . 
   Plunger head  18  is connected to the forward terminal of front rod  78 . Front rod  78  and rear rod  80  are externally threaded, with opposite threaded hands as shown in  FIG. 21 . 
   Front rod  78  and rear rod  80  are externally threaded with buttress threads  79 , as shown in  FIG. 21 . The flat side  81  of buttress threads are oriented to take the load which is pushing inwards towards turnbuckle  82 . This thread type and orientation prevents the threads on front rod  78  and rear rod  80  from jumping out of the corresponding threads in turnbuckle  82  under considerable linear forces such as that which is encountered when dispensing very viscous substances from a cartridge  10 . 
   The front and rear openings  84 ,  86  of turnbuckle  82  are threaded to mate with the threading on front rod  78  and rear rod  80  such that when turnbuckle  82  is rotated in one direction (forward rotation), front rod  78  will be pushed out the front opening  84  of turnbuckle  82  and rear rod  80  will be pushed out the rear opening  86  of turnbuckle  82 , provided that front rod  78  and rear rod  80  are not allowed to rotate relative to the device for dispensing substance from a cartridge  1  while turnbuckle  82  is rotating. The effect of rotating turnbuckle  82  in this (forward) direction has the effect of extending telescoping plunger assembly  76 . Again, provided that front rod  78  and rear rod  80  are not allowed to rotate, a reversal in the direction of rotation of turnbuckle  82  will cause front rod  78  to be drawn into front opening  84  of turnbuckle  82  and rear rod to be drawn into rear opening  86  of turnbuckle  82 . The effect of rotating turnbuckle  82  in this reverse direction has the effect of compacting telescoping plunger assembly  76 . Extension of telescoping plunger assembly  76  within the device for dispensing substance from a cartridge  1  can be utilized to push base seal  16  into cartridge  10 , which will in turn cause the contents of cartridge  10  to be expelled from delivery cone  14 . When telescoping plunger assembly  76  consists of front rod  78 , rear rod  80  and intermediate turnbuckle  82  as described above, telescoping plunger assembly  76  is able to be extended and compacted (that is telescope) along its long axis, while retaining strength along its cross-sectional axis as the elements of telescoping plunger assembly are being telescoped. 
   Rotation of rear rod  80  is prevented by attaching the rear terminal of rear rod  80  to the cap  54  at the end of transmission housing  52  via fixation nut  88 . Rotation of the front rod  78  is prevented by attaching the rear terminal of rod  78  to the front terminal of rod  80  via key  90 . As seen in  FIG. 5 , paddle  92  is attached to the front end of key  90 , and rests in keyway slot  94  in front rod  78 . As illustrated in  FIG. 11 , keyway slot  94  is comprised of two opposed channels  96 ,  98  which are cut into the inner bore  100  of front rod  78 . As seen in  FIG. 6 , terminus  102  of keyway slot  94  is closed, preventing paddle  92  from disengaging from keyway slot  94 . Pin  104  is attached to the rear end of key  90 , and rests in keyway slot  106  in rear rod  80 . Keyway slot  106  is comprised of a single channel  108  which is cut into the inner hollow  112  of rear rod  80 . Terminus  114  of keyway slot  106  is closed, preventing pin  104  from disengaging from keyway slot  106 . 
   Front rod  78  is bored out so that the diameter of bore  100  is greater than the outer diameter of rear rod  80 . Rear rod  80  is hollowed out so that the hollow  112  is dimensioned so that key  90  fits inside of hollow  112 . Key  90 , with paddle  92  at its front end and pin  104  at its rear end, is of a fixed length, so that the fixed length defines the maximum and minimum length of telescoping plunger assembly  76 . The shortest length that telescoping plunger assembly  76  can have is defined as being when turnbuckle  82  is rotated in one direction (reverse direction) such that the front end of paddle  92  is pressed up against the front end of bore  100  and the rear end of pin  104  is pressed up against the rear end of hollow  112 . Full retraction of telescoping plunger assembly  76  is seen in  FIG. 9 . The maximum length that telescoping plunger assembly  76  can have is defined as being when turnbuckle  82  is rotated in the opposite direction (forward direction) such that the rear end of paddle  92  is pressed up against the terminus  102  of keyway slot  94 , which spans bore  100 , and the front end of pin  104  is pressed up against terminus  114  of keyway slot  106 , which spans hollow  112 . Almost full extension of telescoping plunger assembly  76  is seen in  FIG. 10 . 
   Turnbuckle  82  is driven by drive train assembly means  116  which consists of a motor which is connected to a drive assembly  74 . Drive assembly  74  consists of the parts of the device for dispensing substance from a cartridge  1  which transfer the force provided by a motor to telescoping plunger assembly  76  in a manner that will allow telescoping plunger assembly  76  to extend and compact, that is drive linkage  77  and the parts that prevent at least a portion of the telescoping plunger assembly from rotating relative to gun  1 . In the embodiment of the invention illustrated in  FIG. 1 , the motor is a reversible drill  118  (an external power source) which is connected through a drive linkage  77 , the details of which can be seen in  FIG. 13 , consisting of a primary spur gear reduction unit  120 , a drive shaft  122 , a secondary gear reduction unit  124 , an output gear  126 , and a drive hub  128 , which is connected to drive pins  154  and  156  and alignment cage  158 , which rotate turnbuckle  82 . In the embodiment shown in  FIG. 1 , the motor is something which is adapted from a tool (i.e. drill  118 ) that most home handipersons or trades persons have available to them, making gun  1  more affordable and easily adaptable. Similarly, the device for dispensing substance from a cartridge  1  may be made to be adaptable to other external power sources. Ideally other external power sources would be pre-existing tools which are able to provide rotational force such as reversible motorised screwdrivers or grinders. Gun  1  may also be fitted with its own internal motor. An internal AC motor, connectable to household current or a DC motor connected to a battery pack or household current through a transformer are well known, and either is adaptable to power gun  1  through a suitable drive train. 
   The embodiment of the invention utilizing a reversible drill  118  as a motor will now be described in greater detail, with the understanding that other suitable motors are equally adaptable to the present invention. Gun  1  is detachably mounted on drill  118  via adapter block  130 . This mounting can be achieved in a variety of ways that are well known such as a screw clamp, but the simplest and probably the best method is a simple strap  132  which passes through slots  134  in transmission frame members  70 ,  72  and secures around the body of drill  118  with a detachable closure such as a VELCRO™ hook and loop closure. The chuck  136  of drill  118  engages shaft  138 , which drives a series of gears which make up primary spur gear reduction unit  120 . Primary spur gear reduction unit  120  drives secondary gear reduction unit  124  through drive shaft  122 . Secondary gear reduction unit  124  terminates with final gear  126 . Final gear  126  is held between two plates  140  and  142 , which are fixed at their lower ends to transmission frame members  70 ,  72  at points  144  and  146 , respectively. Drive hub  128  is made of hub flange  148  and hub collar  150 . Hub flange  148  rests in front of plates  140  and  142 , and hub collar  150  passes through plates  140  and  142 , allowing hub collar  150  to engage with the inner surface of output gear  126 , which allows output gear  126  to rotate drive hub  128 . Support ring  152  is affixed to the back end of hub collar  150 , holding drive hub  128  in place on either side of plates  140  and  142 . Drive pins  154  and  156  protrude out the front of drive hub  128  and are connected to an alignment cage  158  which sits within turnbuckle  82 . Rotation of the drive hub  128  therefore indirectly drives rotation of turnbuckle  82 , allowing for the extending and compacting of telescoping plunger assembly  76 . The method by which the drive hub  128 , alignment cage  158  and turnbuckle interact in the preferred embodiment to drive telescoping plunger assembly  76  will be described in detail once additional components of telescoping plunger assembly  76  and drive train means  116  are introduced. 
   Drive shaft  122  ideally is split into a forward driveshaft  172  and a rearward driveshaft  174  connected by clutch  176 . Clutch  176  is split into at least two portions along its longitudinal axis. Annular grooves  178  and  180  at its forward and rearward end receive spring clips  182  and  184  which hold clutch  176  together. Forward driveshaft  172  and rearward driveshaft  174  have a non-circular cross-sectional profile and rest in recess  186  in clutch  176 . In the embodiment illustrated in  FIG. 13 , the cross-sectional profiles of the forward and rearward driveshafts  172  and  174  and the recess  186  are hexagonal, but any mating non-circular cross-sectional profiles will do. When telescoping plunger assembly  76  is either at its fully extended or fully compacted position, front rod  78  and rear rod  80  will stop moving, which will, in turn, cause turnbuckle  82 , alignment cage  158 , drive pins  154  and  156 , drive hub  128 , output gear  126 , and secondary gear reduction unit  124  to stop rotating, stopping rearward driveshaft  174 . As drill  118  will continue to drive primary spur gear reduction unit  120 , forward driveshaft  172  will continue to rotate while rearward driveshaft  174  will be stopped. Clutch  176  will stop rotating, to some extent, relative to forward driveshaft  172 , and clutch  176  will continue to rotate, to some extent, relative to rearward driveshaft  174 . When forward driveshaft  172 , clutch  176 , and rearward driveshaft  174  rotate at different rates, the portions of clutch  176  separate. As spring clips  182  and  184  will oppose the separation of clutch  176 , a thunking noise will be made when forward and rearward driveshafts  172  and  174  move relative to recess  186 , thereby alerting the operator that telescoping plunger assembly  76  has reached either end of its travel. 
   In a preferred embodiment of the present gun  1 , it is desirable to be able to unload an empty cartridge  10  (that is, when telescoping plunger assembly  76  is fully extended) and reload a full cartridge  10  (that is, when telescoping plunger assembly  76  is fully compacted) without manually having to rewind telescoping plunger assembly  76  by reversing the direction of rotation of turnbuckle  82 .  FIGS. 7 to 9 ,  12 ,  16 , and  17  illustrate a splitting fast rewind means comprising turnbuckle mechanism  190  whereby turnbuckle  82  is able to split into two halves,  192  and  194 . When turnbuckle halves  192  and  194  separate (disengage), plunger assembly  76  consequently becomes fully extended as plunger biassing spring means generally designated by reference numeral  196  engage, whereby plunger biassing springs  198  and  200  are released and expand. The rearward end of plunger biassing spring  198  is connected to cap  54  and the forward end of plunger biassing spring  198  is connected to an inner recess  202  of drive hub  128 . The rearward end of plunger biassing spring  200  is connected to inner surfaces  204  and  206  of turnbuckle halves  192  and  194 , respectively, and the forward end of plunger biassing spring  200  is connected to the rearmost end of front rod  78 . Turnbuckle halves  192  and  194  can open and close on the rearward end of plunger biassing spring  200  as the rearward end of plunger biassing spring  200  is squared. The rearward end of biassing spring  200  is contained by alignment cage  158  and the squared end slides on the inner surfaces  204  and  206  of the turnbuckle halves  192  and  194 . When turnbuckle halves  192  and  194  separate, inner surfaces  204  and  206  maintain contact with the rearward end of plunger biassing spring  200 . The rearward end of plunger biassing spring  200  is always centred, relative to turnbuckle halves  192  and  194 , as the alignment cage  158  is pinned to drive hub  128  via pins  154  and  156 . When a cartridge  10  is placed into canister  12 , plunger head  18  rests up against base seal  16  of cartridge  10  due to the force exerted by plunger biassing springs  198  and  200  in keeping telescoping plunger assembly  76  extended. As cartridge  10  is placed into canister  12  and finally held in place with cap  22 , telescoping plunger assembly  76  is compacted, but plunger biassing springs  198  and  200  continue to exert force along the length of gun  1 , keeping plunger head  18  flush against the base seal  16  of cartridge  10 . Plunger biassing springs  198  and  200  will keep telescoping plunger assembly  76  maximally extended when a cartridge  10  is placed in canister  12  of gun  1 , no matter whether cartridge  10  is full or only partially full. As long as plunger biassing springs  198  and  200  have similar outward longitudinal tension strength, the two plunger biassing springs will be equally extended about drive hub  128  when turnbuckle halves  192  and  194  are disengaged. Once turnbuckle halves  192  and  194  are engaged, turnbuckle  82  is free to be rotated to drive telescoping plunger assembly  76  as previously described. 
   The mechanism by which turnbuckle halves  192  and  194  are engaged and disengaged is illustrated in  FIGS. 7 to 9 ,  10  and  12 . 
   Turnbuckle half  192  is composed of a semi-cylindrical shell  208  having a forward plug  210  having an inward semi-cylindrical face  212  and a rearward plug  214  having a semi-cylindrical face  216 . Turnbuckle half  194  is composed of a semi-cylindrical shell  218  having a forward plug  220  having an inward semi-cylindrical face  222  and a rearward plug  224  having a semi-cylindrical face  226 . Semi-cylindrical faces  216 ,  212 ,  222  and  226  are all threaded and dimensioned to mate with the threading on the exterior surfaces of front rod  78  and rear rod  80 , as the case may be. Alignment cage  158  rests within the cylindrical shells  208  and  218  of turnbuckle halves  192  and  194 , and rearward of forward plugs  210  and  220  and forward of rearward plugs  214  and  224 , thereby holding turnbuckle halves  192  and  194  in place along the length of gun  1 . The inner bore  228  of alignment cage  158  is slightly larger than the diameter of front rod  78  and of plunger biassing spring  200 , such that front rod  78  and plunger biassing spring  200  can rest within the inner bore  228  of alignment cage  158 . The front face  230  of alignment cage  158  incorporates diametrically opposed cam slots  232  and  234  which accept cam followers  236  and  238  respectively. Cam follower  236  is imbedded in the middle of front plug  210  in turnbuckle half  192 . Cam follower  238  is imbedded in the middle of front plug  220  in turnbuckle half  194 . The rearmost end of alignment cage  158  accepts drive pins  154  and  156  from drive hub  128 . Drive pin  156  protrudes through clearance slot  240  in rearward plug  224  of turnbuckle half  194  and connects to drive hub  128  at point  242 . Drive pin  154  protrudes through clearance slot  244  in rearward plug  214  of turnbuckle half  192  and connects to drive hub  128  at point  246 . Rearward plugs  214  and  224  of turnbuckle halves  192  and  194  support cam follower pins  248  and  250  respectively which engage cam slots  252  and  254  of drive hub  128 . Rotation of drive hub  128  in the forward direction causes an equal, corresponding, rotation of alignment cage  158 , which is connected to drive hub  128  through drive pins  154  and  156 . 
   Engagement of turnbuckle halves  192  and  194  is accomplished through applying a braking force to turnbuckle  82  while drive hub  128  is rotating in the forward direction. A preferred embodiment of a braking means mechanism which will achieve this result is best illustrated in  FIG. 11 . Brake actuator mechanism  256  is contained within ring  46 . Brake actuator mechanism  256  consists of engagement buttons  258  and  260 , brake shoes  262  and  264 , friction surfaces  266  and  268 , and biassing springs  270  and  272 . One assembly of brake engagement button  258 , brake shoe  262 , friction surface  266  and biassing spring  270  is set up on one side of ring  46 , and an other similar assembly of brake engagement button  260 , brake shoe  264 , friction surface  268  and biassing spring  272  is set up on the opposite side of ring  46 . When brake engagement buttons  258  and  260  are depressed, biassing springs  270  and  272  (leaf springs in the preferred embodiment illustrated in  FIG. 11 ) engage brake shoes  262  and  264  and friction surfaces  266  and  268  are pressed up against the outer surface of turnbuckle  82 . Not much braking force is required to retard turnbuckle  82 , as drive pins  154  and  156  do not come into direct contact with turnbuckle halves  192  and  194 , but rather pass through clearance slots  244  and  240 , respectively. However the continued rotation of alignment cage  158  causes drive pins  154  and  156  to move from one side of clearance slots  244  and  240  to the other. While this rotation is occurring cam follower pins  250 ,  248 ,  236  and  238  move from one side to the other side of cam slots  252 ,  254 ,  232  and  234  respectively, causing turnbuckle halves  192  and  194  to close down (engage). Once turnbuckle halves  192  and  194  are engaged, brake actuator mechanism  256  is released, allowing turnbuckle  82  to rotate in the forward direction. 
   When cam follower pins  250 ,  248 ,  236 , and  238  interact with cam slots  252 ,  254 ,  232 , and  234 , respectively, causing turnbuckle halves  192  and  194  to close down, threads on semi-cylindrical faces  212  and  222  mate with the corresponding threads on the external face of front rod  78  and threads on semi-cylindrical faces  216  and  226  mate with the corresponding threads on the external face of rear rod  80 , thereby engaging turnbuckle  82  with front rod  78  and rear rod  80 . Once turnbuckle  82  is engaged, rotation of drive hub  128  in either direction (i.e. forward or reverse) will not cause turnbuckle halves  192  and  194  to disengage because the initial rotational torque is not strong enough to disengage the turnbuckle halves  192  and  194  when the motor is turned on to rotate the drive hub  128  in the either the forward or the reverse direction. 
   Separation of turnbuckle halves  192  and  194  is accomplished through applying a braking force to turnbuckle  82  while drive hub  128  is rotating in the reverse direction. A preferred embodiment of a braking means mechanism which will achieve this result is best illustrated in  FIG. 11 . Brake actuator mechanism  256  is contained within ring  46 . Brake actuator mechanism  256  consists of engagement buttons  258  and  260 , brake shoes  262  and  264 , friction surfaces  266  and  268 , and biassing springs  270  and  272 . One assembly of brake engagement button  258 , brake shoe  262 , friction surface  266  and biassing spring  270  is set up on one side of ring  46 , and an other similar assembly of brake engagement button  260 , brake shoe  264 , friction surface  268  and biassing spring  272  is set up on the opposite side of ring  46 . When brake engagement buttons  258  and  260  are depressed, biassing springs  270  and  272  (leaf springs in the preferred embodiment illustrated in  FIG. 11 ) engage brake shoes  262  and  264  and friction surfaces  266  and  268  are pressed up against the outer surface of turnbuckle  82 . Not much braking force is required to retard turnbuckle  82 , as drive pins  154  and  156  do not come into direct contact with turnbuckle halves  192  and  194 , but rather pass through clearance slots  244  and  240 , respectively. However the continued rotation of alignment cage  158  causes drive pins  154  and  156  to move from one side of clearance slots  244  and  240  to the other. While this rotation is occurring cam followers  250 ,  248 ,  236  and  238  move from one side to the other side of cam slots  252 ,  254 ,  232  and  234  respectively, causing turnbuckle halves  192  and  194  to disengage. 
   Front plug  210  in turnbuckle half  192  contains two bored wells  274  and  276 . Front plug  220  in turnbuckle half  194  incorporates two bored wells  278  and  280 . Well  274  in turnbuckle half  192  lines up with well  278  in turnbuckle half  194 , and the two collinear wells  274  and  278  contain separation spring  282 . Well  276  in turnbuckle half  192  lines up with well  280  in turnbuckle half  194 , and the two collinear wells  276  and  280  contain separation spring  284 . Separation springs  282  and  284  serve to prevent relative rotation of turnbuckle halves  192  and  194  upon the disengagement of turnbuckle  82 . 
   Turnbuckle  82  is joined to drive hub  128  by a circumferential clip  286  which fits into grooves  288  and  290  on turnbuckle halves  192  and  194 , respectively, and groove  292  on drive hub  128 . Circumferential clip  286  is a C-clip, which will allow for the engagement and disengagement of turnbuckle halves  192  and  194  while still holding drive hub  128  to turnbuckle  82 . Without circumferential clip  286 , disengaged turnbuckle halves  192  and  194  are only held to drive hub  128  indirectly through drive pins  154  and  156  which connect alignment cage  158  to drive hub  128 . 
   When one is expelling substance from a cartridge  10  mounted in the gun, it is desirable to have fine control over the termination of substance delivery. Ordinarily, when one is expelling substance and one stops telescoping plunger assembly  76  abruptly, the contents of cartridge  10 , being viscous, will continue to ooze out of delivery cone  14 . One can stop the flow of substance abruptly by withdrawing telescoping plunger assembly  76 . This abrupt withdrawal can be accomplished by reversing the direction of rotation of turnbuckle  82  through reversing the direction of rotation of the motor driving turnbuckle  82 , but this process can be cumbersome if done manually. If the motor is part of gun  1 , then a backfeed circuit can be constructed that will automatically turn on the motor in a reverse direction for a brief second or two when the motor is first turned off. 
   An example of a passive and an active backfeed circuit are illustrated in  FIGS. 14 and 15 , respectively. The passive circuit comprises an AC or a DC power supply; a power switch; a bridge rectifier to convert an AC input to DC; a resistor-capacitor timer circuit; a three pole two-position momentary contact switch to supply power to a motor; and a DC motor. The power switch connects/isolates power between the source input and the control circuit. Closure of the switch charges a capacitor to the output voltage of the bridge. The two-position momentary contact switch isolates the motor. Activation of the two-position momentary contact switch provides power continuity for the motor which will run until the two-position momentary contact switch is deactivated. Deactivation of the two-position momentary contact switch isolates power supply and allows a timed discharge of the capacitor through the motor, reversing the motor&#39;s direction of rotation for a timed period which is dependant of the relative values of the resistor and the capacitor. The active circuit comprises an AC or a DC power supply; a power switch; a bridge rectifier to convert an AC input to DC; a single pole, single throw momentary contact switch to supply power to a power transistor bridge; a transistor bridge to supply power to a motor for forward or reverse rotation, and a variable timer unit consisting of a timer and a resistor to provide timed reverse of motor rotation. The power switch connects/isolates power between the source input and the control circuit. Closure of the single pole, single throw momentary contact switch activates transistors T 1  and T 2  in the transistor bridge providing continuity to the motor and timer and the motor will run until the single pole, single throw momentary contact switch is deactivated. Deactivation of the single pole, single throw momentary contact switch will result in the timer unit providing a timed signal which activates transistors T 3  and T 4  powering the motor in a reverse direction for a programmable period of time. 
   If gun  1  is being powered by an external power source such as drill  118  or an electric screwdriver, a simple reversal of direction of the drill or screwdriver can be utilized to achieve the same effect as an automatic reverse function when the external power source is turned off. Often it is cumbersome to find the switch and manually reverse the direction of rotation of a drill or electric screwdriver when an operator is concentrating on the application of caulking (or other similar substance) from the gun. In such an instance it may be easier for the operator to merely turn off the power source and squeeze together handles  37 ,  39  on C-clamp  41 , which is positioned over the rear portion  38  of canister  12 . This squeezing will disengage canister  12  from ring  46  (as previously described) and allows the operator to pull cartridge  10  and canister  12  away from the gun, which is abruptly breaks contact between plunger head  18  of telescoping plunger assembly  76  and base seal  16  of cartridge  10 , thereby stopping the flow of substance from cartridge  10  through delivery cone  14 . 
   Gun  1  can additionally be fitted with a means for guiding the delivery of substance from the delivery cone (or a bead application guide)  14  along the surface of which the substance is being applied. Guide mount  60  is attached towards the front end of canister  12 , as is seen in  FIG. 1 . Guide mount  60  has a forward-facing horizontal channel  320  and a vertical channel  322 . Horizontal channel  320  and vertical channel  322  have cross-sectional profiles which are key hole shaped, and are adapted to grip various guides through a snap fit. 
   Three bead application guides are shown in  FIGS. 18 ,  19 ,  20  and  21 . Joist guide  324  and seam guide  326  are shown in  FIGS. 18   s  and  10  respectively and adjustable guide  348  is shown in  FIGS. 20 and 21 . Joist guide  324  has a cylindrically shaped top edge  328  which can be snap fitted into either horizontal channel  320  or vertical channel  322  of guide mount  60 . Guide arms  330  and  332  extend from either side of the body  336  of joist guide  324 . Joist guide  324  is used by positioning guide arms  330  and  332  on either side of a joist  400  thereby aligning delivery cone  14  towards the middle of the joist. Joist  400  is not part of the present invention, but is rather an external surface to which substance is being applied. Substance can therefore be expelled from the gun while it moves along the length of the joist and keeping arms  330  and  332  on either side of the joist. A substance bead running the length of the joist can therefore be produced. A variety of different sized joist guides  324  can be produced having different widths of body  336 , which would be adaptable to various widths of joist. 
   Seam guide  326  comprises top edge  338  with a key hole shaped cross sectional profile which can be snap fitted into either horizontal channel  320  or vertical channel  322  of guide mount  60 . Arms  340  and  342  extend down equally from either side of top edge  338  and join at axle  344 , about which wheel  346  is free to rotate. When seam guide  326  is mounted in either horizontal channel  320  or vertical channel  322 , wheel  346  is aligned with the centre of delivery cone  14 . Wheel  346  can be rolled over a seam,  401 , thereby positioning delivery cone  14  over the seam. Seam  401  is not part of the present invention, but is rather an external surface to which substance is being applied. If substance is being expelled from a cartridge  10  contained in the gun, it will be deposited along the length of the seam. 
   Adjustable guide  348  has a top edge  350  with a key hole shaped cross-sectional profile which can be snap fitted into either horizontal channel  320  or vertical channel.  322  of guide mount  60 . Adjustable guide arms  352  and  354  extend downwardly from the back face  403  of the body  358  of adjustable guide  348 . Adjustable arms  352  and  354  are connected to gears  360  and  362  which are mounted on the front face  356  of the body  358  of adjustable guide  348  via pivots  364  and  366  respectively. Gears  360  and  362  intermesh so that when one is rotated about its pivot, the other is rotated by an equal amount in the opposite direction; consequently when the position of either adjustable guide arm  352  or  354  is adjusted in the plane of the rear face  403  of the body  358  of the adjustable guide, the other adjustable guide arm will be automatically positioned along that plane at an equal angle from an imaginary perpendicular plane bisecting adjustable guide arms  352  and  354 . The position of adjustable guide arms  352  and  354  can be locked by inserting pin  368  into hole  370  in the rear face  403  of the body  358  of adjustable guide  348 . When inserted in hole  370 , pin  368  abuts at least one of the teeth of either gear  360  or  362 , which prevents the rotation of both gears  360  and  362 . Adjustable guide arms  352  and  354  terminate in feet  372  and  374 , which are able to rest on a surface to which substance is being applied.  FIG. 20  illustrates feet  372  and  374  resting on surface  376  (surface  376  is not part of gun  1 , but is rather an external surface to which substance is being applied), thereby steadily positioning delivery cone  14  above surface  376 . 
   As was described earlier, canister  12  can be rotated about ring  46 , thereby positioning any guide mounted in guide mount  60  at a convenient position relative to the positioning of the operator who is holding the gun. 
   Gun  1  may also be outfitted with a tip cutter  300  for cutting delivery cone  14  of cartridge  10  and a puncture rod  302  for piercing the cartridge seal that is found at the forward end of most commercially manufactured cartridges just posterior of the delivery cone. Tip cutter  300  and puncture rod  302  are mounted on the front surface of primary gear reduction unit  120  or some other convenient location on the gun. Tip cutter  300  and puncture rod  302  are illustrated in  FIG. 22 , which shows them when they are not mounted on gun  1 . Tip cutter  300  has two cylindrical receiving slots  304  and  306 , which are made of a compliant material, with longitudinal slits  308  and  310  along their respective lengths. Consequently, receiving slots  304  and  306  are able to receive a delivery cone  14  that is inserted into them and hold the cone tightly. Delivery cone  14  can be inserted more or less deeply into either receiving slot  304  or  306 , depending on how far from the tip one wants to cut the delivery cone  14 . Guillotine blade  312  is held and slides within chopping slot  314  in tip cutter body  316  at such an angle to conveniently open the end of delivery cone  14  when delivery cone  14  is placed in receiving slot  304  or  306  and guillotine blade  312  is depressed within chopping slot  314 . Receiving slots  304  and  306  may be at any convenient angle but in  FIG. 22 , receiving slot  304  is angled at approximately forty-five degrees to guillotine blade  312  and receiving slot  306  is angled at approximately ninety degrees to guillotine blade  312 . Practically, any angle between ninety and forty-five degrees is optimal. An angle slightly less than forty-five degrees is still convenient, but as the plane of chopping slot  314  gets closer to that of receiving slot  304 , the cut produced at the tip of delivery cone  14  will become less well suited to deliver a smooth bead of substance from cartridge  10 . Tip cutter  300  may also be comprised of a hole in the face  318  of the tip cutter rather than a receiving slot. 
   Puncture rod  302  may be used to puncture the front seal in cartridge  10  found just posterior to the tip of delivery cone  14  after the tip of delivery cone  14  has been cut by merely inserting the end  303  of puncture rod  302  into the cut tip delivery cone  14 . 
   The present device can be made primarily of plastic or nylon material, or a combination of the two, except for the motor, electrical contacts and some of the drive parts. Plastic/nylon components are more durable than the metal components that have been used in substance delivery guns in the past as plastic/nylon components are more resistant to dents and to corrosion. Plastic/nylon components can additionally be more lightweight and less costly than similarly sized metal components. 
   Various detachable nipples may be used with the present device for dispensing substance from gun  1  for the creation of specific bead shapes from the flow of substance dispensed from the cartridge  10  through the delivery cone  14 . Several such nipples are illustrated in  FIGS. 24   a, b  and  c.  Each nipple  600  is hollowed out and has a base end  602  dimensioned to fit over the delivery cone  14  at the front of cartridge  10  when cartridge  10  is placed in cannister  12 . Each nipple  600  additionally has a collar  604  at its base end  602  which abuts the front end of cartridge  10  when nipple  600  is placed over delivery cone  14 . Nipple  600  is held in place over delivery cone  14  when retaining cap  22  is swung into position over nipple  600  covering delivery cone  14  and collar  604  which abuts the front end of cartridge  10 , in the same manner that was described earlier for swinging retaining cap  22  into position over delivery cone  14  when nipple  600  was not being used. 
   With reference to  FIGS. 25   a, b  and  c,  the tip  606  of each nipple has a shaping surface at its opening. As substance is being expelled through the delivery cone  14  of a cartridge  10  in the gun, it is passed through the inner surface of the nipple and is directed towards the orifice  608  at the tip of the nipple, through which substance is expelled and where the substance meets shaping surface  610 . As the substance being expelled from the cartridge is viscous, it will take the shape of the shaping surface at the orifice at the tip of the nipple. For example, nipple  612  has a shaping surface which will produce a bead with a ribbed top and a semi-cylindrical bottom surface, nipple  614  will produce a bead with a triangular cross-sectional profile, and nipple  616  will produce a semi-cylindrical bead. These examples are given as being illustrative of what shapes of beads can be created using the detachable nipples and are not intended to limit the scope of what is the invention being described. Differently configured shaping surfaces will create beads with different shapes and are intended to be captured in the detachable nipples being described herein. 
   Several variations of the invention presently described will be understood by one skilled in the art to come within the scope of the present invention. The only limitations on the scope of the present invention intended by the inventor are the following, attached claims.