Abstract:
A power tool system which includes a first base unit and a second base unit. The first and second base units each include a housing, a motor housed in the housing, a coupler which is operatively connected to and selectively drivable by the motor and a trigger for activating the motor to drive the coupler. The system also includes a first attachment head which is removably couplable with both the first base unit and the second base unit so that it can be driven by the respective motor of the base unit to which it is attached and a second attachment head which is removably couplable to the first base unit, but which is not couplable with the second base unit.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/926,453 filed Jan. 13, 2014 and U.S. Provisional Application No. 61/821,009 filed May 8, 2013, the entire disclosures of which are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    In order to increase the ease of use and flexibility, some handheld power tools have allowed interchangeability of tool heads. Permitting interchangeability of the tool heads, while keeping the same tool body, allows for the same tool body to operate as a variety of different tools—such as a drill, drill/driver, circular saw, sander, jigsaw, etc. 
         [0003]    It has further been known to have more than one tool body which will receive a particular tool head, for example having one tool body that is corded and another that is a battery operated cordless tool body. 
         [0004]    It may be beneficial to provide an improved power tool system with interchangeable tool heads which can selectively fit onto various of the available tool bodies. 
       SUMMARY OF THE INVENTION 
       [0005]    According to one aspect of the invention, there is a power tool system including a first power tool base unit and a second power tool base unit, each of the first and second power tool base units including a housing and a motor surrounded by the housing; a first coupler operably connected to the motor; and a trigger for activating the motor. The power tool system may further include a first attachment head, the first attachment head including a second coupler and being removably couplable to the first power tool base unit and also being removably couplable the second power tool base unit, the second coupler being coupled together with the respective first coupler when the attachment head is attached to one of the base units. The power tool system further including a second attachment head, the second attachment head also including a second coupler and being removably couplable to the first power tool base unit; the second attachment head not being removably couplable to the second power tool base unit. 
         [0006]    The first power tool base unit may be a cordless unit and the second power tool base unit may be a corded unit. 
         [0007]    The first power tool base unit may be a cordless unit with a first motor and the second power tool base unit may be a cordless unit with a second motor, the second motor being different than the first. The second motor may have more power than the first motor. 
         [0008]    The first attachment head may be a drill head and the second attachment head may be a shear shrubber head. 
         [0009]    According to another aspect, an embodiment of the application comprises a power tool system including a first base unit including a first housing, a first motor housed in the first housing and a first coupler operatively connected to and selectively drivable by the first motor. The power tool system further includes a second base unit including a second housing, a second motor housed in the second housing and a second coupler operatively connected to and selectively drivable by the second motor. The power tool system further includes a first attachment head including a third coupler, the first attachment head being removably couplable with the first base unit such that when the first attachment head is coupled to the first base unit, the third coupler is coupled with the first coupler, the first attachment head being removably couplable with the second base unit such that when the first attachment head is coupled to the second base unit, the third coupler is coupled with the second coupler. This embodiment further includes a second attachment head including a fourth coupler, the second attachment head being removably couplable with the first base unit such that when the second attachment head is coupled to the first base unit, the fourth coupler is coupled with the first coupler. The second attachment head is not removably couplable with the second base unit. 
         [0010]    The first coupler may be identical to the second coupler and the third coupler may be identical to the fourth coupler. 
         [0011]    The second attachment head may include a lockout protrusion. 
         [0012]    The first base unit may include a lockout recess which receives the lockout protrusion when the second attachment head is coupled to the first base unit. 
         [0013]    The second base unit may include an abutting member which prevents the second attachment head from being coupled to the second base unit. 
         [0014]    One of the first power tool base unit and the second attachment head may include a lockout protrusion and the other of the first power tool base unit and the second attachment head includes a lockout recess and the lockout recess may receive the lockout protrusion when the second attachment head is coupled to the first power tool base unit. 
         [0015]    The first power tool base unit may be a cordless unit and the second power tool base unit may be a corded unit. 
         [0016]    The first motor may have a different design than the second motor. 
         [0017]    The first motor is may be a DC motor and the second motor may be an AC motor. 
         [0018]    The first attachment head may be a drill tool head. 
         [0019]    According to another aspect, there is a power tool system including a first base unit including a first housing, a first motor housed in the first housing and a first coupler operatively connected to the first motor and a first trigger for activating the first motor so that it drives the first coupler. A second base unit includes a second housing, a second motor housed in the second housing and a second coupler operatively connected to the second motor and a second trigger for activating the second motor so that it drives the second coupler. A first attachment head includes a third coupler, the first attachment head being removably couplable with the first power tool base unit such that when the first attachment head is coupled to the first power tool base unit, the third coupler is coupled with the first coupler and can be driven by the first motor. A second attachment head includes a fourth coupler, the second attachment head being removably couplable with the first power tool base unit such that when the second attachment head is coupled to the first power tool base unit, the fourth coupler is coupled with the first coupler and can be driven by the first motor. The first attachment head is also removably couplable with the second power tool base unit such that when the first attachment head is coupled to the second power tool base unit, the third coupler is coupled with the second coupler and can be driven by the first motor. The second attachment head is not removably couplable with the second power tool base unit. 
         [0020]    One of the first power tool base unit and the second attachment head may include lockout protrusion and the other of the first power tool base unit and the second attachment head may include a lockout recess and the lockout recess receives the lockout protrusion when the second attachment head is coupled to the first power tool base unit. 
         [0021]    The second attachment head may include the lockout protrusion and the lockout protrusion prevents the second attachment head from being coupled to the second power tool base unit. 
         [0022]    The first power tool base unit may be a cordless unit and the second power tool base unit may be a corded unit. 
         [0023]    The first attachment head may include a sander tool head. 
         [0024]    The first attachment head may include a saw tool head. 
         [0025]    The first attachment head may include a drill tool head. 
         [0026]    According to another aspect, there is a power tool system including a first base unit including a first housing, a first motor housed in the first housing and a first coupler operatively connected to and selectively drivable by the first motor. The system further includes a second base unit including a second housing, a second motor housed in the second housing and a second coupler operatively connected to and selectively drivable by the second motor. The system further includes a third base unit including a third housing, a third motor housed in the third housing and a third coupler operatively connected to and selectively drivable by the third motor. The system further includes a first attachment head including a fourth coupler, the first attachment head being removably couplable with the first base unit such that when the first attachment head is coupled to the first base unit, the fourth coupler is coupled with the first coupler, the first attachment head being removably couplable with the second base unit such that when the first attachment head is coupled to the second base unit, the fourth coupler is coupled with the second coupler and the first attachment head being removably couplable with the third base unit such that when the first attachment head is coupled to the third base unit, the fourth coupler is coupled with the third coupler. The system further includes a second attachment head including a fifth coupler, the second attachment head being removably couplable with the first base unit such that when the second attachment head is coupled to the first base unit, the fifth coupler is coupled with the first coupler and the second attachment head being removably couplable with the second base unit such that when the second attachment head is coupled to the second base unit, the fifth coupler is coupled with the second coupler. The system further includes a third attachment head including a sixth coupler, the third attachment head being removably couplable with the first base unit such that when the third attachment head is coupled to the first base unit, the sixth coupler is coupled with the first coupler. The second attachment head is not removably couplable with the third base unit. The third attachment head is not removably couplable with the second base unit and is not removably couplable with the third base unit. 
         [0027]    The first attachment head may be a saw tool head. 
         [0028]    The first attachment head may be a drill tool head. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0029]      FIG. 1  is a side view of a power tool according to an exemplary embodiment of the invention with a drill head attached; 
           [0030]      FIG. 2  illustrates the power tool with the tool head detached; 
           [0031]      FIG. 3  illustrates a drill head tool head attachment; 
           [0032]      FIG. 4  is a perspective view of a coupling portion of the power tool base unit; 
           [0033]      FIG. 5  is a perspective view of a coupling portion of the tool head; 
           [0034]      FIG. 6  is a cut-away view showing the internals of the base unit with the drill tool head attached; 
           [0035]      FIG. 7  is a cut-away view showing the internals of the base unit with the drill tool head detached; 
           [0036]      FIG. 8  is a perspective view of a corded base unit; 
           [0037]      FIG. 9  is a perspective view of a cordless base unit which receives a  3 -cell battery pack; 
           [0038]      FIG. 10  is a side view of a power tool according to an exemplary embodiment of the invention with a jig saw head attached; 
           [0039]      FIG. 11  is a side view of a power tool according to an exemplary embodiment of the invention with a sander head attached; 
           [0040]      FIG. 12  is a side view of a power tool according to an exemplary embodiment of the invention with an impact driver head attached; 
           [0041]      FIG. 13  is a side view of a power tool according to an exemplary embodiment of the invention with a two speed hammer drill head attached; 
           [0042]      FIG. 14  is a side view of a power tool according to an exemplary embodiment of the invention with a oscillating tool head attached; 
           [0043]      FIG. 15  is a side view of a power tool according to an exemplary embodiment of the invention with a router tool head attached; 
           [0044]      FIG. 16  is a side view of a power tool according to an exemplary embodiment of the invention with a trim saw head attached; 
           [0045]      FIG. 17  is a side view of a power tool according to an exemplary embodiment of the invention with an inflator tool head attached; 
           [0046]      FIG. 18  is a close-up side view of the power tool of  FIG. 1  showing the center of gravity; 
           [0047]      FIG. 19  is a close-up side view of the power tool of  FIG. 11  showing the center of gravity; 
           [0048]      FIG. 20  is a close-up side view of the power tool of  FIG. 16  showing the center of gravity; 
           [0049]      FIG. 21  is a side view of a power tool according to an exemplary embodiment of the invention with a reciprocating saw tool head attached; 
           [0050]      FIG. 22  is a side view of the reciprocating saw tool head of  FIG. 21 ; 
           [0051]      FIG. 23  is a cross-sectional view of the reciprocating saw tool head of  FIG. 22 ; 
           [0052]      FIG. 24  is a perspective view of a coupling portion of the tool head according to another exemplary embodiment; 
           [0053]      FIG. 25  is a perspective view of a coupling portion of a power tool base unit according to another exemplary embodiment; 
           [0054]      FIG. 26  is a perspective view of another exemplary embodiment of a coupling portion of a tool head; and 
           [0055]      FIG. 27  is a perspective view of another exemplary embodiment of a coupling portion of a base unit. 
       
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0056]    The exemplary embodiments of the present application are related to power tools having base units tool bodies with interchangeable tool heads, this general type of tool having been shown in, for example, U.S. Pat. No. 6,634,439, which is incorporated herein in its entirety by reference. 
         [0057]      FIGS. 1-3  show an exemplary embodiment of a power tool according to the present application.  FIG. 1  illustrates a cordless power tool base unit (tool body) with a drill as the power tool head.  FIG. 2  shows the base unit alone and  FIG. 3  shows the drill tool head alone. 
         [0058]    As shown in  FIGS. 1-3 , the tool comprises a tool base unit  100  and a removably attached tool head  200 . In this case the tool head  200  is a drill head. The tool base unit  100  includes a motor housing portion  101  a handle  102  extending from the motor housing portion and a foot  103  at the far end of the handle  102 . The tool base unit  100  further includes a ledge  104  that helps to support the drill head  200 . A trigger  120  is used to activate the motor  400 . 
         [0059]    As shown in  FIG. 1 , the motor housing has a longitudinal axis A. The longitudinal axis A is co-incident with the longitudinal axis of the motor housed in the motor housing  101 . Additionally, the handle  102  has a longitudinal axis B. According to the exemplary embodiment, the handle  102  is located substantially mid-way between a front end and a rear end of the motor housing  101  and is substantially perpendicular to the motor housing  101 . According to exemplary embodiments of the application, the angle θ between the longitudinal axis of the handle B and the longitudinal axis A of the motor housing  101  may be between 50 and 120 degrees. In  FIG. 1 , the handle  102  is substantially perpendicular to the motor housing  101  and it is contemplated that exemplary embodiments of the tool which have an angle θ between 65 and 115 degrees, and particularly between 70 and 110 degrees, provide good ergonomics for at least the drill tool head  200 . 
         [0060]    Typical power tools have only a single configuration and any tool head is not readily removable and interchangeable with other tool heads. Because the tool heads in such typical power tools are simply integrated into the power tool, the tool head is held in place by non-removable construction. In a power tool system with removable and interchangeable heads the tool head is removable and therefore not attached in the permanent manner of standalone power tools. In an exemplary embodiment of the present application, there is provided a power tool system with a base unit with a ledge  104  which is substantially parallel to an axis of the motor  400  and/or the longitudinal axis A of the motor housing. The tool ledge  104  allows the tool to have a single mid-handle  102  that is angled with respect to the longitudinal axis A of the motor housing, while sufficiently supporting the tool head. Having a ledge  104  of this type also allows for a good portion of the tool head to be exposed so that controls can be exposed for the user on another side of the tool head (see, for example, the two speed hammer drill head  262  having a gear change shifter  272  as shown in  FIG. 13 ). The design also allows for tool shapes such as the trim saw shown in  FIG. 16  without unnecessarily increasing the distance between the power tool trigger and the work surface. 
         [0061]    The drill head  200  and the tool base unit  100  meet at an interface C. The ledge  104  extends forward from this interface C generally along line D and a line running through the interface intersects the trigger  120 . 
         [0062]      FIGS. 4 and 5  illustrate the coupling features of the tool base unit  100  and the tool head  200 , respectively, in more detail. As shown in  FIG. 4 , the tool base unit  100  has a front face  105  of the motor housing  101 . The front face  105  of the motor housing abuts against the rear face  230  of the drill head  200 . The plane in which the front face  105  and the rear face  230  meet forms the interface C of  FIG. 1 . 
         [0063]    As seen in  FIG. 4 , the base unit  100  has a generally circular opening  150  into which a coupling portion of the tool head  200  can be fit. Inside the circular opening  150 , there is also a motor mount opening  160  which exposes the motor mount  161 . A male coupler  110  which is coupled to the motor and spins with the motor shaft is at a center of the motor mount  161 . The male coupler  110  transfers mechanical power from the tool base unit  100  to the tool head  200 . Adjacent to the motor mount opening  160  is a first recessed face  151 . The first recessed face  151  has several features for mating with the tool head  200 , including slots  152 , ribs  153  and cutout  154 . There is a second recessed face  155  in a direction towards the tool head  200  and a plurality of ribs  106  at corners of the first recessed face  151 . 
         [0064]    Furthermore, as can be seen in  FIG. 4 , the ledge  104  has an opening  107  for receiving a contact plate  420  of the tool head  200 . The contact plate  420  contacts a plate member  430  and together they serve as a lock-out as described in further detail in U.S. Patent Application Publication No. 2013/0020103, which is hereby incorporated by reference (the same reference numbers are not used in U.S. Patent Application Publication No. 2013/0020103 as in the present application). 
         [0065]    The coupling portion of the tool head  200  is shown in  FIG. 5 . As shown in  FIG. 5 , the tool head  200  has a rear face  230  that abuts the front face  105  of the tool head when the tool head  200  is coupled to the tool base unit  100 . Additionally, the tool head has a plate  201  that is screwed onto the rear face  230  with screws  202 . A first protrusion  210  protrudes from the plate  201  towards the tool base unit  100 . There are four receiving corners or slots  211  which receive the ribs  106  of the tool base unit  100 . 
         [0066]    The tool head  200  coupling portion further includes a second protrusion portion  220  which extends from the first protrusion  210 . The second protrusion portion  220  is generally cylindrical in shape. It includes slots  221 , protrusions  222  and ribs  223 . It further includes a recess  224  which receives a spring  425  (see  FIG. 6 ). When coupled to the tool base unit  100 , the slots  221  receive the ribs  153 , the protrusions  222  fit in the slots  152  and the ribs  223  slide into the cutout  154 . Furthermore, the tool head  200  includes a female coupler  250  which engages the male coupler  110  of the tool base unit. Additionally, the spring  425  sets into the recess  224  to axially lock the tool head  200  in place. The spring  425  and recess  224  of the present application operate similarly to the spring and recess combination shown in U.S. Pat. No. 6,634,439. While this exemplary embodiment shows the base unit coupler  110  being male and the tool head coupler  250  being female, these could be reversed. Similarly, the other various mating features could be reversed. 
         [0067]    As shown in the exemplary embodiment, the features of the plate  201  directly mate with those of the motor mount  161 . As can be appreciated, in a tool system with interchangeable heads according to an exemplary embodiment of the present application, the male coupler  110  is aligned with the female coupler  250  in order to transfer drive from the motor  400  to the tool head  200  and the output of the tool head  200 . In the present exemplary embodiment, the motor  400  is clamped tightly into the motor housing  101  and the male coupler  110  and female coupler  250  have to be closely aligned. By making the tolerance alignment features on the plate  201  and the motor mount  161 , as described above, unnecessary tolerance stack-up (as may be seen if the outside of the motor housing  101  were used for tolerance alignment) is avoided. That is, at least some of the features on the plate  201  and the motor mount  161  are used as alignment features. If features on the outside of housing of the drill head  200  were used in conjunction with features on the motor housing  101  to align the tool head  200  and the tool base unit  100 , there can be a much more significant tolerance stack-up, because of the number of assembled parts between the alignment features and the male and female couplers  110 ,  250 , which are aligned to transfer power from the motor  400  to the tool head  200 . 
         [0068]      FIGS. 6 and 7  show internals of the base unit  100  (the base units  100 ′ of FIGS.  8  and  100 ″ of  FIG. 9  includes similar internal features). As shown in these figures, the base unit  100  of the tool has a motor  400  (in the exemplary embodiment of  FIG. 1  a DC motor; in the exemplary embodiment of  FIG. 8  an AC motor). The motor  400  has a motor fan  401  at its front end for dissipating heat. The exemplary motor additionally has a brush ring  402  and a commutator  403 . An output shaft  404  extends from the motor and provides drive to the male coupler  110 . At its rear end, the motor  400  is supported by a shaft  410  which is partially covered by insulation  412 . The shaft  410  may be integral and continuous with shaft  404  or may be a separate second shaft. At the rear end of the shaft  410 , there is a bearing  411  supported in the housing. The motor  400  is activated by the variable speed trigger  120  and provides power to the base unit coupler  110 . 
         [0069]    As shown in  FIG. 7 , the trigger  120  is attached to a switch  130 . Pulling the trigger  120  activates the switch  130  which in turn causes power to be provided to the motor  400 . The motor  400  provides rotational power to the base unit coupler  110  which rotates the tool head coupler  250  of a tool head that is coupled to the base unit. In this embodiment, the switch  130  and trigger  120  are variable speed, such that the speed of the motor  400  can be varied by pulling the trigger  120  more or less. 
         [0070]    As shown in  FIGS. 8 and 9 , more than one type of tool base unit is contemplated.  FIG. 1  shows a power tool base unit  100  which receives a slide-type battery pack  300 .  FIG. 8 , on the other hand, is a corded base unit  100 ′ and receives AC power and has an AC motor. For the corded base unit  100 ′ shown in  FIG. 8 , the area at the bottom of the handle near where the cord is located is considered a foot. There may also be base units with different types of battery packs. For example,  FIG. 9  shows a base unit  100 ″ which receives a 3-cell type battery pack. Other battery packs, such as a tower pack, are also contemplated. The battery packs may differ both in the mechanical interface and power/voltage. Additionally, the same tool head may fit into each of the different base units  100 ,  100 ′ and  100 ″. For example, the drill head  200  with the coupling show in  FIG. 4  may fit into the base unit  100 , as shown in  FIG. 1 , and alternatively into the base unit  100 ′ of  FIG. 8  or  100 ″ of  FIG. 9 . Likewise, when the sander head operates as the tool head, as shown in  FIG. 11 , it may fit into a base unit with a sliding battery pack as shown in  FIGS. 1 and 11 . It may also fit with the base units of  FIGS. 8 and 9 . This allows a user to have both a cordless and a corded system using the same tool heads. 
         [0071]      FIGS. 10-17  and  21  illustrate the power tool system with a variety of different tool heads. Particularly,  FIG. 10  illustrates a jig saw head  266   FIG. 11  shows a sander head  260 ;  FIG. 12  illustrates an impact driver  261 ;  FIG. 13  illustrates a two speed hammer drill  262 ;  FIG. 14  shows an oscillating tool  267 ;  FIG. 15  illustrates a router  263 ;  FIG. 16  illustrates a trim saw  264 ;  FIG. 17  illustrates an inflator  265 ; and  FIG. 21  illustrates a reciprocating saw  268 . Each of these tool heads  260 - 268  have a coupling section as shown in  FIG. 5  for the drill head  200 . That allows each of the tool heads  260 - 268  to similarly fit with a base unit with a sliding battery pack as shown in  FIGS. 10-17  and  21  or one of the other base units as shown in  FIGS. 8 and 9 . Each of these tool heads  260 - 268  have a coupling section as shown in  FIG. 5  for the drill head  200 . 
         [0072]    A cut-away view of the reciprocating saw tool head  268  is shown in  FIG. 23 . The reciprocating saw tool head of the exemplary embodiment uses a scotch-yoke mechanism, but other known reciprocating saw tool heads may also be used. In the reciprocating saw tool head, drive power is transmitted to the tool head through the female coupler  250 , as with the other tool heads. That drive power is transferred through a transmission  300 , including various bearings  301  and shafts  302 , to a pinion  304 . The pinion  304  has teeth which mesh with a drive gear  305 . The drive gear  305  has a roller/sleeve bearing  306 . The roller/sleeve bearing  306  is offset from the central axis of the drive gear  305 , so that it rotates in a circular pattern as the drive gear  305  is rotated. In turn, the roller/sleeve  306  bearing engages with a hole  311  in the reciprocating shaft  310 . Thus, as the roller/sleeve bearing  306  moves forward, it pushes the reciprocating shaft  310  forward and when the roller/sleeve bearing moves backward it pulls the reciprocating shaft  310  backwards to impart a reciprocating motion on the reciprocating shaft  310 . A front end of the reciprocating shaft  310  has a blade clamp  312  which holds a saw blade  313  and can be released by means of a saw blade release lever  314  (see  FIGS. 21 and 22 ). 
         [0073]    As discussed above, the design of the exemplary embodiment of the power tool system shown in the present application allows for the work surface to be spaced an efficient distance from the tool trigger. As shown in the figures, the drill driver  200 , impact driver  261 , sander  260 , router  264 , trim saw  265  and oscillating  267  tool heads each have distances from the action point of the trigger  120  to the work surfaces which are less than 110 mm. The two speed hammer drill  262  is has a trigger to work surface distance that is somewhat longer due to the additional gears needed to provide a hammer mode and a gear change. However, it still has a trigger to work surface distance of less than 150 mm. 
         [0074]    As discussed above, it is contemplated that a tool head with a particular coupling may fit into more than one base unit. It is further contemplated that various tool heads may include a coupling with a lockout feature, so that they may fit into some base units and not others. 
         [0075]    For example,  FIG. 24  is a perspective view of another exemplary embodiment of a coupling portion  215  for a tool head and  FIG. 25  is a perspective view of another exemplary embodiment of a coupling portion for a base unit. The lockout tool head coupling portion  215  is the same as the coupling portion shown for tool head  200  in  FIGS. 3 and 5 , except that the lockout coupling portion  215  additionally includes lockout features  225 . Similarly the base unit coupling portion  216  shown in  FIG. 25  is the same as the coupling portion of the power tool base unit  100  shown in  FIG. 4 , except that the lockout base unit coupling portion  216  shown in  FIG. 25  does not include recesses  157 . 
         [0076]    As shown, the coupling portion  215  shown in  FIG. 24  includes a pair of lockout features  225  in the form of protrusions which protrude radially inwardly from the generally cylindrical second protrusion  220 . When the tool head having the coupling portion  215  shown in  FIG. 24  is attached to the base unit  100  shown in  FIG. 1  with the coupling portion shown in  FIG. 4 , the lockout features  225  fit into the recesses  157 . Since the lockout feature  225  is able to fit into the recesses  157 , they do not block the tool head  216  from being inserted into the base unit  100  with a coupling portion as shown in  FIG. 4 . In this manner, a tool head with the coupling section  215  having a lockout feature  225  may be coupled to the base unit including a coupling section as shown in  FIG. 4  and the tool may be operated in the same manner as when the tool head  200  with the coupling portion shown in  FIGS. 3 and 5  is coupled to the base unit. Particularly, when a tool head with the lockout coupling portion  215  is engaged with the base unit, the male couple  110  and the female coupler  250  are engaged and the motor can drive the tool head through this connection. 
         [0077]    On the other hand, a base unit having the lockout base unit coupling  216  shown in  FIG. 25  has no recesses for receiving the lockout features  225 . Accordingly, there is no space for the lockout features  225  to be received when a user attempts to couple a tool head with coupling section  215  into a base unit with lockout coupling section  216 . Therefore, when a user tries to insert a tool head with the lockout coupling section  215  into a base unit with base unit lockout coupling section  216  shown in  FIG. 25 , the lockout features  225  contacts the second protrusion  220 , a portion of which serves as an abutting member and prevents further insertion of the tool head with the lockout coupling section  215  into the base unit with the lockout coupling section  216 . Particularly, in the embodiment, the lockout features  225  prevent the tool head coupler  250  from effectively engaging with the base unit coupler  110  and also prevents the spring  425  from becoming engaged with the recess  422 . Accordingly, the tool head  215  with the lockout features  225  can be inserted only into a base unit with the recesses  157 , as shown in  FIG. 4 , and cannot be inserted into a base unit without the recesses, as shown in  FIG. 25 . 
         [0078]    The lockout tool coupling section  215  having lockout feature  225  may be added to any of the tool heads shown and described herein, such as the jig saw head  266  of  FIG. 10 , the sander head  260  of  FIG. 11 ; the impact driver  261  of  FIG. 12 ; the two speed hammer drill  262  of  FIG. 13 ; the oscillating tool  267  of  FIG. 14 ; the router  263  of  FIG. 15 ; the trim saw  264  of  FIG. 16 ; the inflator  265  of  FIG. 17 ; and the reciprocating saw  268  of  FIG. 21 ; or to other power, outdoor, cleaning or other tool heads which may be used with the system. Additionally, any of the base units (i.e., those of  FIG. 1 ,  8  or  9 ) may include an interface with recesses  157  as shown in  FIG. 4  or an interface without recesses  157  to make a lockout tool coupling  216 , as shown in  FIG. 25 . Accordingly, for example, the base units  100  and  100 ″ may have an interface with recesses  157  and base unit  100 ′ may have an interface without the recesses  157 . Alternatively, base units  100  may have an interface with recesses  157  and base unit  100 ′ and  100 ″ may have an interface without the recesses  157 . 
         [0079]    It is further contemplated that there may be more than two types of head couplings and two types of base unit couplings so that there is a system of lock-outs with various tool head fitting various base units. The various base units may be different in how they are powered or in other aspects, such as the size of the motor or other components. For example,  FIG. 26  shows another exemplary embodiment of a coupling section for a tool head and  FIG. 27  shows another exemplary embodiment of a coupling section for a base unit in which there is a single lockout feature  225  and a single recess  157 , respectively. The selective lockout tool head coupling section  217  shown in  FIG. 26  is the same as the coupling section shown in  FIGS. 5 and 24 , except that the coupling section  217  of  FIG. 26  includes a single lockout feature  225  (whereas  FIG. 5  shows a coupling section with no lockout feature and  FIG. 24  shows a coupling section with a pair of lockout features  225 ). Similarly the selective lockout base unit coupling section  218  shown in  FIG. 27  is the same as the coupling portions shown in  FIG. 4  and  FIG. 25 , except that the coupling section  218  of the base unit shown in  FIG. 27  includes a single recess  157  for receiving a single lockout feature  225  ( FIG. 4  having a pair of recesses  157  and  FIG. 25  having no recesses  157 ). The coupling section  217  shown in  FIG. 26  can be applied to any of the tool heads discussed herein and the coupling section  218  shown in  FIG. 27  can be applied to any of the base units  100 ,  100 ′,  100 ″. 
         [0080]    As can be appreciated, a tool head having a coupling section  217  with a single lockout feature  225 , as shown in  FIG. 26 , can be removably coupled to a base unit that has a corresponding recess  157  for the single lockout feature  225 . Accordingly, a tool head with the coupling section  217  shown in  FIG. 26  (single lockout feature  225 ) can be coupled to a base unit with a single recess  157 , as shown in  FIG. 27 , and can also be coupled to a base unit with a pair of recesses  157 , as shown in  FIG. 4 . However, it cannot be coupled to a base unit having the coupling section  216  with no recesses, shown in  FIG. 25 . That is, it can be coupled to two of the three exemplary base unit coupling sections. 
         [0081]    A tool head which includes a coupling section having no lockout features, as is shown in  FIG. 5  does not require that the base unit coupling section have any recesses, but may also be coupled to base units with coupling sections that do include one or more recesses. Accordingly, a tool head with the coupling section of  FIG. 5  may be coupled to a base unit with a coupling section with no recesses ( FIG. 25 ), one recess  157  ( FIG. 27 ) or two recesses ( FIG. 4 ). On the other hand, a tool head which includes a coupling section having two lockout features  225 , as is shown in  FIG. 24 , must be fit to a base unit which includes two recesses  157  for receipt of the two lockout features  225 . Accordingly, a tool head which includes the coupling section shown in  FIG. 24  having two lockout features  225  can be coupled with a base unit with the coupling section shown in  FIG. 4  having two corresponding recesses  157  for receiving the two lockout features  225 . However, it cannot be coupled with a base unit having a coupling section with only a single recess  157  ( FIG. 27 ) or no recess  157  ( FIG. 25 ) because at least one of the lockout features  225  will contact the second protrusion  220 , a portion of which serves as an abutting member and prevent the male and female couplers  110 ,  250  from becoming engaged and/or the spring  425  from becoming engaged with the recess  422 . 
         [0082]    It is contemplated by this disclosure that there may be a variety of other power tool heads not specifically shown in the figures These other power tool heads may include, for example, outdoor power tool heads and/or cleaning power tool heads. A non-exhaustive list of such tool heads includes a rotary cutter, rotary tool, hammer drill, right angle drill, close quarter drill, powered scissors, jig saws, metal cutting saws, tile saws, random orbit sander, polishers, paint removal tools, laminate tools, cut-off tools, nailers, staplers, shears, impact wrenches, reversible angle drills, ratchet wrenches, spray guns, paint sprayers, a vacuum cleaner head, a barbecue cleaner, rotating and reciprocating brushes. Other tools may be adapted to run on the power transferred from the base units  100 ,  100 ′,  100 ″ to the tool head may also be used with the system, even if not specifically mentioned here. These tool heads may be constructed in a variety of manners and be powered by the power tool base units  100 ,  100 ′,  100 ″ described herein. The tool heads may be oriented in a variety of manners to provide the best access to a workpiece. For example, a rotary tool power tool head may rotate along the same or a parallel axis as the motor  400  or it may rotate along an axis perpendicular to the motor, or along an axis that is neither parallel nor perpendicular to the motor. Likewise, a reciprocating brush could reciprocate along the same or parallel axis as the motor  400 , perpendicular to the motor, or at an angle to both. Various gear assemblies or other power transmission mechanism may transfer the power to provide the appropriate orientation. 
         [0083]    The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied. Such variations are not to be regarded as a departure from the invention and all such modifications are intended to be included within the scope of the invention. 
         [0084]    Example embodiments are provided. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.