Patent Abstract:
An angle grinder is provided including a rotating handle configuration allowing the handle of the angle grinder to be locked in different positions relative to the angle grinder housing. A switch mounting configuration is provided for simplifying the assembly of the switch device. A gear wheel lock mechanism is also provided to allow the grinding wheel spindle to be prevented from rotating during removal or installation of a grinding wheel on the spindle. A gear case cooling and air bleed arrangement are also provided.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application claims the benefit of U.S. Provisional Application No. 60/347,426, filed on Jan. 10, 2002. The disclosure of the above application is incorporated herein by reference in its entirety. 

   FIELD OF THE INVENTION 
   The present invention generally relates to angle grinders, and generally describes various features of a large angle grinder (LAG). It will be appreciated, however, that other angle grinders are known in the art, including medium angle grinders (MAG) and small angle grinders (SAG). Therefore, it will be further appreciated that each of the herein described features may be readily adapted for use with a LAG, MAG, and/or SAG. 
   BACKGROUND AND SUMMARY OF THE INVENTION 
   Angle grinding tools are commonly used for grinding and sanding applications. Angle grinders include a rotary shaft for driving a grinding wheel mounted thereon. The present application describes several improvements for angle grinders. 
   Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
       FIG. 1  is a side, partial cross-sectional view of a large angle grinder according to the principles of the present invention; 
       FIG. 2  is a cross-sectional view of a rotatable handle having a handle lock in an engaged position; 
       FIG. 3  is a cross-sectional view of the handle lock in a disengaged position; 
       FIG. 4  is a perspective view of a rotating trigger switch for a large angle grinder; 
       FIG. 5  is a cross-sectional view of the rotating trigger switch of  FIG. 4  taken along line  5 - 5 ; 
       FIG. 6  is an cross-sectional view of the rotating trigger switch of  FIG. 4  taken along line  6 - 6 ; 
       FIG. 7  is a schematic view of an alternative switch of the rotating trigger switch arrangement for a large angle grinder; 
       FIG. 8  is cross-sectional view of a handle portion including a switch carrier mounting system and a paddle switch; 
       FIG. 9  is a perspective cross-sectional view of the handle portion of  FIG. 8  detailing the paddle switch; 
       FIG. 10  is a perspective view of an interconnection mechanism for the switch carrier mounting system; 
       FIG. 11  is a cross-sectional view of the handle portion including a mechanical motor brake illustrated in a braking mode; 
       FIG. 12  is a cross-sectional view of the handle portion including the mechanical motor brake illustrated in a non-braking mode; 
       FIG. 13  is a perspective schematic view of components of a motor according to an embodiment of the present invention; 
       FIG. 14  is a schematic view of a first preferred embodiment of a soft start circuit; 
       FIG. 15  is a graphical representation of a voltage jump using the soft start circuit of  FIG. 14 ; 
       FIG. 16  is a schematic view of an alternative embodiment of a soft start circuit; 
       FIG. 17  is a graphical representation of a voltage ramp using the soft start circuit of  FIG. 16 ; 
       FIG. 18A  is a plan view of a first exemplary embodiment of a motor armature; 
       FIG. 18B  is a perspective view of a motor armature detailing an exemplary embodiment of a winding scheme; 
       FIG. 19  is a perspective view of a brush housing of the motor; 
       FIG. 20  is a plan view of the brush housing of  FIG. 19 ; 
       FIG. 21  is a perspective view of an alternative brush housing of the motor; 
       FIG. 22  is a plan view of the brush housing of  FIG. 21 ; 
       FIG. 23  is a schematic illustration of a preferred field winding arrangement; 
       FIG. 24  is side view of the field winding arrangement; 
       FIG. 25  is a cross-sectional view of the field winding arrangement; 
       FIGS. 26 through 28  are schematic illustrations of alternative field winding arrangements; 
       FIG. 29  is a cross-sectional view of an air flow and labyrinth path system of the large angle grinder; 
       FIG. 30  is a front view of a stator assembly of the air flow system of  FIG. 29 ; 
       FIG. 31  is a cross-sectional view of a bearing support section of the large angle grinder including a felt ring; 
       FIG. 32  is a cross-sectional view of the bearing support structure of the large angle grinder including an alternative placement for the felt ring of  FIG. 31 ; 
       FIG. 33  is a side view of a pinion gear having a reinforcing ring; 
       FIG. 34  is a bottom view of the pinion gear of  FIG. 33 ; 
       FIG. 35  is a side view of the pinion gear of  FIG. 33  detailing interconnection with a motor spindle; 
       FIG. 36  is a top view of a housing having an air cooled gear case; 
       FIG. 37  is a perspective view of a gear case including a radial spindle lock; 
       FIG. 38  is a perspective internal view of the gear case of  FIG. 37 ; 
       FIG. 39  is a top internal view of the gear case of  FIG. 37 , detailing components of the radial spindle lock; 
       FIG. 40  is a cross-sectional view of the gear case of  FIG. 37 ; 
       FIG. 41  is a side view of a keyless blade clamp; 
       FIG. 42  is a cross-sectional view of the keyless blade clamp of  FIG. 41  taken along line  42 - 42 ; 
       FIG. 43  is a side cross-sectional view of an alternative embodiment of a keyless blade clamp; 
       FIG. 44  is a top view of a bearing assembly implemented with the alternate embodiment of the keyless blade clamp of  FIG. 43 ; 
       FIG. 45  is a detailed view of a ball bearing in a first position within the bearing assembly; 
       FIG. 46  is a detailed view of a ball bearing in a second position within the bearing assembly; 
       FIG. 47  is a perspective view of a large angle grinder having a spindle lock; 
       FIG. 48  is a cross-sectional view detailing components of the spindle lock of  FIG. 47 ; 
       FIG. 49  is a perspective view of a large angle grinder including an alternative spindle lock; 
       FIG. 50A  is a cross-sectional view detailing components of the spindle lock of  FIG. 49 ; 
       FIG. 50B  is a plan view of the lever illustrating a disengagement position for the spindle lock of  FIG. 49 ; 
       FIG. 51  is a cross-sectional view of a tool-less grinder wheel removal mechanism illustrated in a clamped position; 
       FIG. 52  is a cross-sectional view of the tool-less grinder wheel removal mechanism of  FIG. 51  illustrated in an unclamped position; 
       FIG. 53  is a cross-sectional view of an alternative tool-less grinder wheel removal mechanism illustrated in a clamped position; 
       FIG. 54  is a cross-sectional view of the alternative tool-less grinder wheel removal mechanism of  FIG. 53  illustrated in an unclamped position; 
       FIG. 55  is a cross-sectional view of a second alternative tool-less grinder wheel removal mechanism illustrated in a clamped position; 
       FIG. 56  is a cross-sectional view of the second alternative tool-less grinder wheel removal mechanism of  FIG. 55  illustrated in an unclamped position; 
       FIG. 57  is a top view of a pin interlock of the second alternative tool-less grinder wheel removal mechanism of  FIGS. 55 and 56 ; 
       FIG. 58  is a cross-sectional view of a portion of a double wall gear case; 
       FIG. 59  is a cross-sectional view of the complete double wall gear case, detailing internal components of the gear case; 
       FIG. 60  is a plan view of an adjustable wheel guard in a latched position; 
       FIG. 61  is a plan view of the adjustable wheel guard of  FIG. 60  in an unlatched position; 
       FIG. 62  is a plan view of an alternative embodiment of an adjustable wheel guard; 
       FIG. 63  is a side view of the adjustable wheel guard of  FIG. 62 ; 
       FIG. 64  is an exploded perspective view of another alternative embodiment of an adjustable wheel guard; 
       FIG. 65  is a plan view of the adjustable wheel guard of  FIG. 64 ; 
       FIG. 66  is a plan view of another alternative embodiment of an adjustable wheel guard in a latched position; 
       FIG. 67  is a plan view of the adjustable wheel guard of  FIG. 66  in a unlatched position; 
       FIG. 68  is a top view of a wheel guard mount having a slot formed therein; 
       FIG. 69  is a side, partial cross-sectional view of a hand adjustable wheel guard; and 
       FIG. 70  is a bottom view of a large angle grinder that implements the hand adjustable wheel guard of  FIG. 69 . 
   

   DETAILED DESCRIPTION 
   With reference to  FIG. 1 , a large angle grinder (LAG)  10  is shown. The LAG  10  includes a housing  12  having a handle portion  14 , a field case  16  and a gear case  18 . The handle portion  14  is preferably fixedly attached to a first end  20  of the field case  16  and the gear case  18  is preferably fixedly attached to a second end  22  of the field case  16 . The handle portion  14  preferably supports a switch  24  and associated components. The field case  16  supports a motor  26  having a motor spindle  28  that extends into the gear case  18  for driving a gearset  30  supported therein. A wheel spindle  32  preferably extends from the gear case  18  and is driven by the motor spindle  28  through the gearset  30 . The axis of rotation of the motor spindle  28  is generally perpendicular to the axis of rotation of the wheel spindle  32 . A grinder wheel  34  is selectively attachable to the wheel spindle  32  and is rotatably driven thereby. 
   The motor  26  is in electrical communication with the switch  24  through wires  36 . The switch  24  is further in electrical communication with a power source via a cord  37  including a plug (not shown). The handle portion  14  preferably includes an opening  38 , opposite the connection end, through which the cord  37  runs. A trigger  40  is in mechanical communication with the switch  24  for selectively supplying power to the motor  26 . The trigger  40  may be pivotably supported at a pivot point  44 , within the handle portion  14 . The trigger  40  preferably includes a bracket  46  that engages with the switch  24 . In a first position, the trigger  40  operates the switch  24  to OFF. Depression of the trigger  40  toward the handle portion  14  operates the switch  24  to ON, thus initiating operation of the LAG  10 . 
   Handle 
   In an exemplary embodiment, shown in  FIGS. 2 and 3  the handle portion, designated as  14 ′, is rotatably connected to the field case  16 . The interconnection between the field case  16  and the handle portion  14 ′ is a lip/groove-type connection. The connection end of the handle portion  14 ′ includes an opening  58  that is generally of a larger diameter than the outside diameter of the connection end of the field case  16 , which is partially received into the handle portion  14 ′. The field case  16  includes a plurality of grooves  60  that receive a plurality of tabs or lips  62  disposed around the internal circumference of the handle portion  14 ′. The lips  62  each include a circumferential bearing surface  64  that engage the grooves  60  for enabling smooth rotation of the handle portion  14 ′ relative to the field case  16 . The lip and groove engagement prevents the field case  16  from being pushed into the handle portion  14 ′ or pulled out of engagement with the handle portion  14 ′. As the handle portion  14 ′ rotates relative to field case  16 , the lips  62  slide radially within the grooves  60 . In a preferred embodiment, first and second felt strips  66  are included for sealing between the handle portion  14 ′ and the field case  16 . The first and second felt strips  66  are disposed within, and adhere to, the grooves  60 , respectively. 
   Trigger 
   With continued reference to  FIGS. 2 and 3 , a handle lock  80  is preferably provided for locking the handle portion  14 ′ in one of a plurality of rotational positions relative to the field case  16 . The handle lock  80  is included to prevent rotation of the handle portion  14 ′ relative to the field case  16  during operation of the LAG  10 . The handle lock  80  is generally quadrant shaped and is pivotably supported at a pivot point  82  within the handle portion  14 ′ and biased in a first (locking) direction by a coil spring  84 . A first face  86  of the handle lock  80  contacts a forwardly extending surface  88  of the trigger  40  and a second face  90  contacts a face  92  of a wall  94  formed about the internal circumference of the handle portion  14 ′. The wall  94  includes a plurality of grooves  96  formed therearound. An arcural face  98  of the handle lock  80  may include a manually engageable lever portion  100  that extends outside of a groove  102  of the handle portion  14 ′. The lever portion  100  is preferably movable in a first direction within the groove  102  against the bias of the spring  84 , causing the handle lock  80  to pivot about the pivot point  82 . 
   In a first position, as illustrated in  FIG. 3 , the handle lock  80  prevents depression of the trigger  40  by obstructing rotational motion of the trigger  40  about the pivot point  44 . The second face  90  of the handle lock  80  is prohibited from pivotal movement about the pivot point  82  by the face  92  of the wall  94 . To engage the handle lock  80 , the handle portion  14 ′ must be sufficiently rotated until the second face  90  aligns with one of the plurality of grooves  96  in the wall  94 . Upon alignment with a groove  96 , the handle lock  80  is biased by the coil spring  84  and pivots, thus seating the second face  90  of the handle lock  80  into the groove  96 . In this second position, the handle lock, prohibits the handle portion  14 ′ from rotating relative to the field case  16 . In addition, the first face  86  of the handle lock  80  no longer obstructs pivotal movement of the trigger  40 , and the trigger  40  is free to initiate operation of the LAG  10 . 
   If rotation of the handle portion  14 ′ is desired, the lever portion  100  is pivoted back within the groove  102 , against the biasing force of the coil spring  84 , and the handle portion  14 ′ is rotated slightly to disalign the handle lock  80  and the groove  96 . The handle portion  14 ′ is then rotatable, until the second face  90  of the handle lock  80  aligns with and subsequently engages another groove  96  when the lever portion  100  is released. 
   With particular reference to  FIGS. 4 through 7 , an alternative embodiment of a trigger is shown. A trigger ring  110  is preferably supported by and rotatable about the handle portion  14 . The handle portion  14  is cylindrical in form and fixed with respect to the field case  16 . The trigger ring  110  is selectively rotatable between the field case  16  and the handle portion  14 , and includes a formed outer diameter having a plurality of peaks  112  for facilitating easy grip. As best seen in  FIG. 5 , the trigger ring  110  may be supported by a plurality of screws  114  that run Within arcural grooves  116  formed through an internal face  118  of the trigger ring  110 . The trigger ring  110  is preferably biased in a first rotational direction by a spring  120  and further includes a contact track  122  formed on the internal face  118 . The contact track  122  includes a lower portion  124  immediately prior to a ramp portion  126  after which is formed a dwell portion  128 . The contact track  122  is preferably arcural in shape, similar to the grooves  116 , and is in contact with a link  130 ′. 
   In a first exemplary embodiment, as shown in  FIG. 6 , the link is a lever arm  130 ′ which is pivotal about a pivot point  132 . A first end  134  of the lever arm  130 ′ includes a contact point  136  that is biased, by a spring  138  acting against the first end  134  of the lever arm  130 ′ and into contact with the contact track  122 . A second end  140  of the lever arm  130 ′ is in mechanical communication with the switch  24 . 
   In a second exemplary embodiment, as shown in  FIG. 7 , the link is a quadrant  130 ″, which is pivotal about a pivot point  132 ″. A first face  142  of the quadrant  130 ″ includes a contact point  144  that is biased by a coil spring  145  acting against a spring tab  143  on the quadrant  130 ″, into contact with the contact track  122 . A link  146  connected to the quadrant  130 ″ is in communication with the switch  24 . 
   For either embodiment, the LAG  10  is OFF when the contact point  136 ,  144 , respectively, is resting within lower portion  124 . As the trigger ring  110  rotates, the contact track  122  rotates relative to the stationary contact point  136 ,  144 , respectively. As the contact point  136 ,  144  encounters the ramp portion  126 , the contact point  136 ,  144  rides upward along the ramp portion  126  and pivots the link thereby switching the LAG  10  ON. With the trigger ring  110  rotated just enough for the contact point  136 ,  144  to be on the ramp portion  126 , any release of the trigger ring  110  will cause the spring  120  to bias the trigger ring  122  back, whereby the contact point  136 ,  144  is again in contact with the lower portion  124  and the LAG  10  is OFF. However, upon sufficient rotation of the trigger ring  110  the contact point  136 ,  144  travels past the ramp portion  126  and into contact with the dwell portion  128 . The dwell portion  128  is generally raised relative to the lower portion  124  and includes a lip  148  for preventing the spring  120  from biasing the trigger ring  122  back. With the contact point  136 ′,  144  in contact with the dwell portion  128 , the LAG  10  is continuously operable without holding the trigger ring  110  in position. To discontinue operation, the trigger ring is turned in an opposite rotational direction with sufficient force for the contact point  136 ,  144  to ride over the lip  148  and back down to the lower portion  124 . 
   (Switch Carrier Mounting System) 
   With reference to  FIGS. 8 through 10 , an alternative trigger system is detailed. The trigger system includes a switch carrier  160  disposed within the handle portion  14  and a paddle trigger  162  for selectively activating a switch  164  supported within the switch carrier  160 . The switch carrier  160  preferably includes a housing  166  for mounting the switch  164  therein and an opening  168  for receiving an arm of the paddle trigger  162  for activating the switch  164 , as will be described in further detail below. The housing  166  preferably includes an end  172  having a shell portion  174  extending therefrom, as best seen in  FIG. 10 . The shell portion  174  includes an upper wall  176  and a pair of sidewalls  178 . The sidewalls  178  each include a formed recess  180  running along their respective lengths. The upper wall  176  includes a generally rectangular opening  182  with a first tab  184  extending upward from an edge  186  of the opening  182 , and also including a recess  188  formed in a front face  190 . 
   The switch carrier  160  is preferably attached to a square hub  192  that extends from the field case  16 . As best seen in  FIG. 10 , the square hub  192  includes a front face  194 , a top face  196 , a bottom face  198  and side faces  200 . In SAG or MAG applications, the square hub  192  preferably houses a bearing (not shown) for rotatably supporting the motor spindle  28  and motor commutator (not shown), and further supports motor brush housings (not shown). Extending upward from the square hub  192  is a second tab  202  having a lip  204  formed on the end. The square hub  192  further includes rails  206  disposed along each side face  200 , running vertically generally parallel to the front face  194 . Each rail  206  includes a sloping front face  208  that terminates into a sloping top face  210  which terminates with a squared back face  212 . 
   The shell portion  174  of the switch carrier  160  may slidably receive a portion of the square hub  192  therein. Specifically, the recesses  180  of the sidewalls  178  of the switch carrier  160  are aligned with the rails  206  of the square hub  192  for slidably receiving the rails  206  therein. As the switch carrier  160  is slid into connection with the square hub  192 , the second tab  202  extends upwards through the opening  182  of the switch carrier  160 . Once the switch carrier  160  is fully received on the square hub  192 , the first and second tabs  184 ,  202  interface, whereby the lip  204  of the second tab  202  is received into the recess  188  of the first tab  184  for releasably engaging the square hub  192  and the switch carrier  160 . The first and second tabs  184 ,  202  are generally formed to produce an interference fit therebetween, thereby biasing the first and second tabs  184 ,  202  into engagement. 
   To disengage the square hub  192  and switch carrier  160 , the second tab  202  is manually biased from engagement with the first tab  184  and the switch carrier  160  is slid from engagement with the square hub  192 . In this manner, the switch carrier  160  of the present invention enables easy assembly and disassembly of the switch  164  into the LAG  10 , thereby simplifying manufacture and easing maintenance. 
   (Paddle Switch) 
   With reference to  FIGS. 8 and 9 , the paddle trigger  162  includes a paddle portion  220  with a first arm  222  extending therefrom. A second arm  224  preferably extends upward from and generally perpendicular to the first arm  222 . A face  226  of the second arm  224  is in contact with the switch  164  for selectively activating the switch  164 . Pivot posts  228  perpendicularly extend from either side of the first arm  222 . The pivot posts  228  are received into apertures  230  of the handle portion  14  for facilitating pivotal support of the paddle trigger  162 . 
   The paddle trigger  162  further includes a paddle lock  232  for selectively preventing depression of the paddle trigger  162 . The paddle lock  232  is pivotally supported by the paddle portion  220  about a pivot  234  and includes a lock switch  236 . The lock switch  236  is biased toward a first position by a coil spring (not shown), whereby the lock switch  236  lays flat against the paddle portion  220 , contouring to the paddle portion  220 . The lock switch  236  is rotatable to a second position, against the bias of the coil spring. In the second position, an end  240  of the lock switch  236  seats within a groove  242  of the handle portion  14 , creating a column between the paddle portion  220  and the handle portion  14 . In this manner, depression of the paddle trigger  162  is prohibited. To enable depression of the paddle trigger  162 , the lock switch  236  is flipped out of engagement with the groove  242 , back to the first position. 
   A locking member  244  is further included and is slidably supported within the handle portion  14 . The locking member  244  locks the paddle trigger  162  in a depressed position, whereby the LAG  10  is continuously activated. 
   (Mechanical Brake for Motor Armature) 
   Once the LAG  10  is in operation, a motor armature spins at a relatively high rate within the field case  16 , as will be discussed in further detail hereinbelow. As a result, the motor armature builds up a significant amount of rotational inertia. Immediately after the LAG  10  is switched off, the motor armature continues to spin within the field case  16 , gradually slowing to a stop. During the gradual slowing of the free-spinning motor armature, the grinder wheel  34  also continues to spin, gradually slowing with the motor armature. As a result, an operator must wait until the armature and grinder wheel  34  slow to a stop before setting the LAG  10  down, changing the grinder wheel  34 , or performing other operations. 
   An exemplary embodiment of the present invention provides a mechanical motor brake  260 , as detailed in  FIGS. 11 and 12 . The mechanical motor brake  260  is preferably in mechanical communication with the trigger  40  of the switch  24  for selective implementation. The trigger  40  is preferably in mechanical communication with a link arm  262 , an end of which is connected to a generally frusto-conically shaped first brake wheel  264  that includes an external brake surface  266 . The first brake wheel  264  is rotatably supported about an extended end of the motor spindle  28  and is fixed from rotation by the handle portion  14  through a spline engagement  268 . The first brake wheel  264 , however, is axially slidable relative to the handle portion  14  along the splines  268 . A spring  270  is also included and is disposed about the motor spindle  28 , immediately behind and in contact with the first brake wheel  264 . The motor spindle  28  extends from the motor  26  and is fixed for rotation with a second brake wheel  272  that includes an internal brake surface  274 . The spring  270  biases the first brake wheel  264  into engagement with the second brake wheel  272 , further biasing the link arm  262  in a forward direction. 
   The first brake wheel  264  is selectively engageable with the second brake wheel  272  for retarding rotational motion of the motor spindle  28 . The trigger  40  includes an elbow arm  276  that slidably interfaces a slot  278  of the handle portion  14  and is pivotally connected to the link arm  262 . The trigger  40  may further include a spring  280  for biasing the trigger  40  to an OFF position (see  FIG. 11 ). Depression of the trigger  40 , to an ON position (see  FIG. 12 ) against the bias of the spring  280 , causes the pivot of the elbow arm  276  and link arm  262  to slide within the slot  278  until contacting an end of the slot  278 , thereby pulling the link arm  262  and first brake wheel  264  out of engagement with the second brake wheel  272 , against the bias of the spring  270 . Once disengaged, the second brake wheel  272  is free to rotate, thus enabling unrestricted rotation of the motor spindle  28 . 
   Upon release of the trigger  40 , the spring  280  biases the trigger  40  to the OFF position, releasing the elbow arm  276  from forced engagement with the end of the slot  278 . In the OFF position, power to the motor  26  is cut and the motor spindle  28  spins freely, as described above. The link arm  262  moves in the forward direction and the first brake wheel  264  again engages the second brake wheel  272 . The engagement of the first and second brake wheels  264 ,  272  retards the inertial rotation of the motor spindle  28 , thereby braking the grinder wheel  34  from free-spin. 
   The mechanical motor brake  260  may optionally include a lock  290  for locking the motor spindle  28  from rotation. The lock  290  is selectively engageable with the second brake wheel  272  and includes a lever arm  292  that is pivotally supported within the handle portion  14  about a generally central pivot point  294 . A first end  296  of the lever arm  292  includes a tooth  298  for selective engagement with a tooth surface  300  disposed about the external circumference of the second brake wheel  272 . The first end  296  of the lever arm  292  further includes a switch  302  that extends through a slot  304  in the handle portion  14  and is slidable on an external surface  306  within the slot  304 . A second end  308  of the lever arm  292  is pivotally attached in a slot  310  by a post  312  that extends from the first brake wheel  264 . Backward and forward movement of the first brake wheel  264 , resulting from depression and release of the trigger  40 , respectively, pivots the lever arm  292  about the generally central pivot point  294 . 
   As shown in  FIG. 11 , the first and second brake wheels  264 ,  272  may be engaged to retard rotational motion of the motor spindle  28 . Additionally, the lever arm  292  is in an engaged position with the second brake wheel  272  thereby, locking the brake wheel  272 , thus prohibiting rotation of the motor spindle  28 . Forward movement of the switch  302  causes the lever arm  292  to pivot about the generally central pivot point  294 . As a result, the tooth  298  of the lever arm  292  is disengaged from the tooth surface  300  of the second brake wheel  272 . Furthermore, the second end  308  of the lever arm  292  slides to an opposing end of the slot  310 . 
   As shown in  FIG. 12 , the lock  290  is prohibited from engagement with the second brake wheel  272  upon depression of the trigger  40 . As the first brake wheel  264  is pulled back from the second brake wheel  272  by depression of the trigger  40 , as described above, the post  312  is also pulled back. As the post  312  is pulled back, the second end  308  of the lever arm  292  contacts an end of the slot  310  and is thus pulled by the post  312 , causing clockwise pivoting of the lever arm  292  about the generally central pivot point  294 . Clockwise pivoting of the lever arm  292  disengages the tooth from the tooth surface  300  of the second brake wheel  272 . In this manner, the lock  290  is prohibited from locking the motor spindle  28  during powered drive of the motor  26 . 
   The lever arm  292  may optionally include a first detent  320  that interfaces a corresponding second detent  322  formed on an internal structure of the handle portion  14 . In an exemplary embodiment, the first and second detents  320 ,  322  are formed from plastic and are therefore, slightly elastic. Alternatively, the first and second detents  320 ,  322  may include first and second springs (not shown). The interface between the first and second detents  320 ,  322  requires an amount of force to be applied to either the first or second ends  296 ,  308  of the lever arm  292  to enable the lever arm  292  to pivot about the generally central pivot point  294 . In this manner, the lock  290  is prohibited from accidental engagement or disengagement. 
   The mechanical motor brake  260  and the lock  290  improve the overall usefulness of the LAG  10 . By immediately braking the rotation of the grinder wheel  34 , the mechanical motor brake  260  enables an operator to quickly access the grinder wheel  34  or perform other duties, without requiring a waiting period for the grinder wheel  34  to slow from the inertial rotation of the motor  26 . Additionally, the lock  290  enables the changing of grinder wheels  34  without requiring an extra tool for preventing the grinder wheel  34  from free spin. 
   Motor 
   The motor  26  is preferably a universal series motor of a type commonly known in the art. With particular reference to  FIGS. 1 and 13 , the motor  26  generally includes the motor spindle  28 , a motor armature  330 , a field pole  332 , field windings  334 , a commutator assembly  336 , brush holders  338  and electrical leads  340 . The electrical leads  340  link brushes  342  to the switch  24  for selective connection with a power source. 
   The field case  16  is preferably of open cylindrical shape supporting the field pole  332  about an inside circumference  344 . The field pole  332  may be formed from sheet-steel laminations fastened to the inside of the field case  16 . The field windings  334  are formed from repetitive windings of wire disposed on either side of the field pole  332 . The field windings  334  generally include “run” windings and “brake” windings. Power from the power source runs through the run windings creating an electric field for causing rotation of the motor armature  330 . After cutting power to the run windings, the motor armature  330  continues to spin, slowly decelerating to a stop, as described in detail above. To reduce the deceleration time, the brake windings generate an electric field, generally opposite that of the run windings, from residual current induced by the spinning motor armature  330 . This feature is described in further detail hereinbelow. 
   The motor armature  330  is preferably fixed for rotation with the motor spindle  28  and comprises a cylindrical core of sheet-steel disks  346  punched with peripheral slots, air ducts and a spindle hole. The disks  346  are aligned on the motor spindle  28 , a first end of which is supported by a bearing  348  at a first end of the field case  16 , through the commutator  336 . A bearing  350  seats within an aperture  352  of the gear case  18  for supporting a second end of the motor spindle  28 . A series of copper conducting wires are wound in various patterns about the peripheral slits of the armature disks  346 , the ends of which are soldered to the commutator  336 . The series of wires are referred to as “windings”  354  (see  FIG. 13 ). 
   The commutator  336  includes hard-drawn copper segments or commutator segments  356 , insulated from each other and the motor spindle by mica. The commutator  336  is fixed for rotation with the motor spindle  28  and provides an electrical connection between the rotating armature  330  and the stationary brushes  342 . The brush holders  338  each slidably support a carbon brush  342  that is in periodic contact with the commutator segments  356 . Generally, the stationary brushes  342  are held in contact with a top surface  358  of the commutator  336  by spring tension (as will be discussed in detail hereinbelow). The brushes  342  complete the electrical link between the rotating commutator  336 , armature  330 , and the switch  24 . 
   (Soft Start Arrangement) 
   The switch  24  acts as an electrical bridge between the motor  26  and a power source. As described previously, the switch  24  is in mechanical communication with the trigger  40 . Depression of the trigger  40  causes the switch  24  to complete the electrical bridge, thus providing power to the motor  26  from the power source. 
   With particular reference to  FIG. 14 , a preferred embodiment of the switch  24  includes a soft start circuit  370 . The soft start circuit  370  may include a first switch  372  in series connection with a resistor  374  and a second switch  376  in parallel connection with the resistor  374 . The first and second switches  372 ,  376  are interconnected wherein the second switch  376  has delayed movement compared to the first switch  372 . The delay period between the first and second switches  372 ,  376  is predefined by a delay mechanism  378 . The delay mechanism  378  may be one of many known in the art, including a spring dampened delay mechanism or the like. The spring dampened delay mechanism transmits movement to the first switch  372  via a spring which operates through a damper that effectively delays operation of the second switch  376  as is known in the art. A first terminal  380  of the soft start circuit  370  is in electrical communication with the power source and a second terminal  382  is in electrical communication with the motor  26 . 
   Depression of the trigger  40  causes the first switch  372  to close, thus providing power to the second terminal  382  through the resistor  374 . During the predefined delay period, the motor  26  is powered at a first voltage V 1  which results from the voltage division created by the resistor  374 . After the delay period, the second switch  376  is closed, thereby powering the motor  26  through the parallel path. This is due to the current seeking the path of least resistance through the soft start circuit  370 . The motor  26  is thereby powered at a second voltage V 2 , directly from the power source, whereby V 2  is greater than V 1 . This is best shown graphically in  FIG. 15 , wherein the time  52  is the time where the second switch  376  is closed. 
   With particular reference to  FIG. 16 , an alternative embodiment of the soft start circuit  370 ′ may include an integrated circuit  384 . A switch  386  and the integrated circuit  384  are disposed between the first and second terminals  380 ,  382 . Depression of the trigger  40  results in closure of the switch  386 , thus powering the motor  26  through the integrated circuit  384 . The integrated circuit  384  functions to ramp the voltage to an operating level, designated as V 0 . This is best shown graphically in  FIG. 17 . 
   The exemplary soft start circuits  370 , 370 ′ described above, provide a slower start voltage for the motor  26 . A slower motor start enables gradual acceleration of the various LAG  10  components, including the motor spindle  28 , gearbox components, wheel spindle  32  and grinder wheel  34 . The initial inertia of these components could cause an uncomfortable jolt if the motor  26  immediately jumped to an operational voltage level. The gradual acceleration provided by the soft start circuit  370  enables smooth start of the LAG  10 , reducing any related jolting. 
   (Motor Abrasion Protection) 
   With particular reference to  FIG. 18A , an alternative embodiment of the armature  330  is designated as  330 ′. The armature  330 ′ preferably includes the motor spindle  28 , a primary laminate stack  390  and a pair of secondary laminate stacks  392 . The secondary laminate stacks  392  are axially aligned with and are disposed on opposing ends of the primary laminate stack  390 . A spacer  394  is included between each of the secondary laminate stacks  392  and the primary laminate stack  390 . Both the primary and secondary laminate stacks  390 ,  392  include a plurality of slots  396  running generally parallel to the axis of the motor spindle  28 . A series of windings  398  are included that are disposed in various patterns through the slots  396  of the primary and secondary laminate stacks  390 ,  392  and wind about ends of the secondary laminate stacks  392 . An abrasion thread  400  is preferably wrapped in a pattern over the windings  398  at the end of the secondary laminate stack  392 , and travels down a single slot  396  in the primary and secondary laminate stacks  390 ,  392  to wrap around the other end of the secondary laminate stack  392  in a similar pattern. As the armature  330 ′ is caused to spin, the abrasion thread  400  protects the windings  398  from abrasion against other motor components. 
   (Motor Winding Scheme) 
   With particular reference to  FIG. 18B , a first exemplary embodiment of a winding scheme is detailed hereinbelow. The winding scheme includes a first wire  410  wound between two slots  412   a ,  412   b  of the armature  330  and a second wire  414  concurrently wound between the same slots  412   a ,  412   b  as the first wire  410 . The ends of the first and second wires  410 ,  414  are soldered to the commutator  336 . It is important to note that the number of times a particular wire is wound around the armature  330  is defined as its number of windings. The winding scheme provides for a different number of windings for the first and second wires  410 ,  414 . In other words, the number of windings about the slots  412   a ,  412   b  for the first wire  410  is unequal to the number of windings for the second wire  414 . 
   (Constant Load Motor Brush) 
   As described previously, the brushes  342  (shown in  FIG. 13 ) provide electrical connection between the rotating commutator  336  and the stationary switch  24  for providing power to the motor  26 . In order for the motor  26  to function properly and perform efficiently, the brushes  342  should constantly and evenly contact the commutator  336 . Additionally, during the life of the motor  26 , the brushes  342  gradually wear. Therefore, traditional motors include compensation devices, such as springs, to press the brushes  342  into contact with the commutator  336 . 
   (Brush Duct) 
   Referencing  FIG. 1 , the LAG  10  also may include the brush housings  338  mounted to respective support structures  422  of the field case  16 . With particular reference to  FIGS. 19 and 20 , the brush housings  338  each include a support plate  424  having a perpendicularly extending bracket  426 . The bracket  426  may include an aperture  428  therethrough for receiving a bolt (not shown) for attaching the brush housing  338  to the field case  16 . A terminal plate  432  is preferably attached to the support plate  424  and includes first and second terminals  434 ,  436 . The first terminal  434  is in electrical communication with the switch  24  and a brush  342  may be connected to the second terminal  436  by a wire (not shown). A brush duct  440  is also provided, through which the brush  342  is slidably disposed. A wall  442  of the brush duct  440  includes a slot  444 , through which an arm  446  of a biasing member  448  passes. In a first exemplary embodiment, the biasing member  448  includes a cylindrical housing  450  having the arm  446  extending tangentially therefrom. The cylindrical housing  450  includes an aperture  452  therethrough whereby the biasing member  448  receives a pivot post  454  of the brush housing  338  for pivotally supporting the biasing member  448 . A coil spring (not shown) is disposed within the cylindrical housing  450  and is anchored to the pivot post  454  for biasing the biasing member  448  about the pivot post  454 , thereby biasing the arm  446  downward through the slot  444 . The arm  446  engages a top face  456  of the brush  342 , thereby biasing the brush  342  downward within the brush duct  440  for slidably engaging the commutator  336 . 
   With reference to  FIGS. 21 and 22 , an alternative biasing member  460  is shown for biasing the brush  342  against the commutator  336  and to compensate for wear of the brush  342  during the lifetime of the motor  26 . The biasing member  460  preferably includes an arm  462  and a biasing spring  464 . A first end  466  of the arm  462  is pivotally attached to a pivot post  468  and a second end  470  of the arm  462  is in contact with the top face  456  not shown of a brush  342 . The spring  464  is connected at a first end to an intermediate length of the arm  462  and is anchored to the support plate  424 . The spring  464  biases the arm  462  downward through the slot  444 , further biasing the brush  342  into contact with the commutator  336 . As the brush  342  wears, the arm  462  continuously biases the brush  342  downward, providing a constant electrical connection between the commutator  336  and the brush  342 . 
     FIGS. 19 and 21  include a preferred embodiment of the brush duct  440  as shown. The brush duct  440  may include a series of recesses  482  that run along a length of an inside wall  484  of the brush duct  440 . The recesses  482  create a gap through which dirt and other debris may escape. As noted previously, during the life of the motor  26  the brushes  342  wear, thus creating debris within the brush duct  440 . The brush duct  440  enables unrestricted slidable movement of the brush  342  within the brush duct  440  by reducing the amount of dirt and debris that would otherwise inhibit brush  342  movement. 
   (Stator Winding) 
   In the simplest terms, current is selectively provided to the motor via the switch  24 . As shown in  FIG. 13 , the current travels through the switch  24  through one of the two brushes  342  to the commutator  336 , or more specifically, to the commutator segment  356  that is presently engaged with the brush  342 . From the commutator bar  356  the current travels through the particular winding  354  soldered to the commutator bar  356 , thereby generating a first flux field about the winding  354 . The current ultimately travels to the end of the winding  354  into an opposing commutator bar that is presently engaged with the second of the two brushes  342 . The second brush  342  is preferably in electrical communication with a first end of the field windings  334  ( FIG. 1 ) thereby enabling the current to travel through the field windings  334 . The field windings  334  run generally parallel to the windings  354  of the armature  330 . As the current travels through the field windings  334 , a second flux field is generated, which is generally opposite to the first flux field. The opposing fields induce a resultant force causing the armature  330  to rotate within the field case  16 . The current ultimately travels through the field windings  334  to ground. 
   With particular reference to  FIG. 23 , a schematic view of a preferred field winding arrangement  490  is detailed. The field winding arrangement  490  includes first and second run windings  492 ,  494  in series, wrapped clockwise about either side of a field pole  496  ( FIG. 24 ). The field winding arrangement  490  further includes first and second brake windings  498 ,  500  in series, wrapped counter-clockwise about either side of the field pole  496 , concurrently with the first and second run windings  492 ,  494  as is shown in  FIGS. 24 and 25 . 
   The first and second run windings  492 ,  494  and the first and second brake windings  498 ,  500  are each in electrical communication with the switch  24 . The switch  24  preferably includes a first sub-switch  502  for completing a powered electrical circuit between the first and second run windings  492 ,  494  and the armature  330 . The switch  24  also preferably includes a second sub-switch  504  for completing a closed electrical circuit between the first and second brake windings  498 ,  500  and the armature  330 . The switch  24  is configured whereby if either sub-switch  502 ,  504  is open, the other is closed. 
   To provide power to the motor  26  the first sub-switch  502  is closed. With the first sub-switch  502  closed, current runs counter-clockwise through the schematic circuit of  FIG. 23 . The current path is as follows: through the first run winding  492 , through the second run winding  494 , through a first brush  342   a , through the armature  330 , through a second brush  342   b  and back around through to ground. The current running through the first and second run windings  492 ,  494  generates an electric field that interacts with an electric field generated through the armature  330 , thereby causing the armature  330  to rotate in a first rotational direction. 
   To cut power to the motor  26  the first sub-switch  502  is opened, thereby closing the second sub-switch  504 . Immediately after closing the second sub-switch  504 , the armature  330  is freely spinning within the motor  26 , thus generating a current that runs clockwise through the circuit. The current path is as follows: through the second brush  342   b , through the second sub-switch  504 , through the first brake winding  498 , through the second brake winding  500  and through the first brush  342   a  back to the armature  330 . As the current passes through the first and second brake windings  498 ,  500 , a flux field is generated that is generally opposite to the flux field previously generated by the first and second run windings  492 ,  494 , described above. The flux field urges the armature  330  to spin in an opposite rotational direction, thereby causing the armature  330  to quickly decelerate. As the armature  330  decelerates, the current through the circuit gradually decreases to zero, where the armature  330  is at rest. The braking scheme thus provides an efficient means for slowing the residual inertial motion of the rotating armature  330 . 
   With reference to  FIGS. 23-25 , the first and second run windings  492 ,  494  are preferably created using a common wire  510 . Initially, the first run winding  492  is wrapped in a clockwise direction around a first side of the field pole  496  then diagonally traverses the field pole  496  to a second side of the field pole  496 , where the second run winding  494  is wrapped in an opposite direction to the first run winding  492 . The first and second brake windings  498 ,  500  are also preferably created using a common wire  512 . Initially, the first brake winding  498  is wrapped in a counter-clockwise direction around the first side of the field pole  496  then diagonally traverses the field pole  496  to the second side where the second brake winding  500  is wrapped in an opposite direction to the first brake winding  498 . In this manner, only three lead wires extend from the field pole  496 , reducing cost and complexity. A first lead wire  514  connects directly to the power source, a second lead wire  516  connects to the switch  24  and a third lead wire  518  connects to the first brush  342   a . The first lead wire  514  is spliced to the first and second run winding  510  at point X in  FIG. 23 . The second lead wire  516  is spliced to the first and second brake winding wire  512  at a point Y. The third lead wire  518  is spliced to both the first and second run winding wire  510  and the first and second brake winding wire  512  at a point Z. The second brush  342   b  is connected to the second sub-switch  504 . In this manner, the number of lead wires are reduced, thereby simplifying manufacture and reducing material costs. 
   (Winding Arrangements) 
   An alternative field winding arrangement  520  is detailed in  FIG. 26 . The field winding arrangement  520  includes first and second run windings  522 ,  524  and first and second brake windings  526 ,  528  parallel to one another, immediately following the second brush  342   b . Closure of the first sub-switch  502  completes an electrical circuit between the run windings  522  and the armature  330  enabling a current from the power source to travel around the circuit. The current path is counter-clockwise and is as follows: from the power source, through the first brush  342   a , through the armature  330 , through the second brush  342   b , through the first and second run windings  522 ,  524 , through the first sub-switch  502  and back to ground. Closure of the second sub-switch  504  completes an electrical circuit between the brake windings  526 ,  528  and the armature  330 . The residual current flow, induced by the free-spinning armature  330 , of the electrical circuit is generally clockwise and is as follows: from the armature  330 , through the second brush  342   b , through the first and second brake windings  526 ,  528 , through the second sub-switch  504  and around through the first brush  342   a  back through the armature  330 . 
   Another field winding arrangement  530  is detailed in  FIG. 27 . The field winding arrangement  530  is similar to the field winding arrangement  520  described immediately above, however, the first run winding  522  is positioned immediately prior to the first brush  342   a . In this manner, the first and second run windings  522 ,  524  are balanced on either side of the armature  330 . This field winding arrangement  530  is generally used for European applications that require specific limitations on the amount of radio and TV interference a motorized tool is allowed to emit. By balancing the first and second run windings  522 ,  524  across the armature  330 , these limitations are achievable. 
   Closure of the first sub-switch  502  completes an electric circuit between the first and second run windings  522 ,  524  the power source and the armature  330 . The current flow is generally counter clockwise and is as follows: from the power source, through the first run winding  522 , through the first brush  342   a , through the armature  330 , through the second brush  342   b , through the second run winding  524 , through the first sub-switch  502  back through to the power source. Closure of the second sub-switch  504  completes an electrical circuit between the brake windings  526 ,  528  and the armature  330 . The residual current flow, induced by the free-spinning armature  330 , of the electrical circuit is generally clockwise and is as follows: from the armature  330 , through the second brush  342   b , through the first and second brake windings  526 ,  528 , through the second sub-switch  504  and around through the first brush  342   a  back through the armature  330 . 
   (Angle Grinder Brake) 
   Yet another field winding arrangement  540  is detailed in  FIG. 28 . The field winding arrangement  540  balances both the first and second run windings  522 ,  524 , as well as the first and second brake windings  526 ,  528 , about the armature  330 . Closure of the first sub-switch  502  completes an electrical circuit, whereby current is provided by the power source and runs counter-clockwise through the circuit, as follows: from the power source, through the first run winding  522 , through the first brush  342   a , armature  330  and second brush  342   b , through the second run winding  524  back through to ground. Closure of the second sub-switch  504  completes another electrical circuit, whereby residual current flow, induced by the free-spinning armature  330 , is generally clockwise and is as follows: from the armature  330 , through the second brush  342   b , through the first brake winding  526 , through the second sub-switch  504  around through the second brake winding  528 , through the first brush  342   a  back into the armature  330 . 
   (Labyrinth Path for Protecting Open Ball Bearings) (Airflow Baffles) 
   With further reference to  FIGS. 1 ,  29  and  30  the LAG  10  includes an airflow assembly  550  for circulating air through the field case  16 . The airflow assembly  550  preferably includes a fan  552  and a stator  554 . The fan  552  is fixed for rotation with the motor spindle  28  and is disposed about the motor spindle  28  immediately following the end of the armature  330 . With particular reference to  FIG. 29 , the fan  552  may include a generally disc shaped main body  556  having a centrally disposed aperture  558  for receiving the motor spindle  28  and a circumferential surface  560  having a plurality of fan blades  562  radially extending therefrom. The fan blades  562  are preferably positioned at an angle (i.e. pitch angle) relative to the axis of rotation of the motor spindle  28 , for inducing airflow through the field case  16  as the fan  552  is caused to rotate. First and second guide walls  564 ,  566  may axially extend from a front face  568  of the main body  556 . A first gap  570  is formed between the first guide wall  564  and an inside circumferential surface  572  defined by a hub portion  573  of the main body  556 . A second gap  574  is formed between the first and second guide walls  564 ,  566 . 
   As detailed in  FIGS. 29 and 30 , the stator  554  is fixedly attached to a back wall  580  of the gear case  18  and extends into the field case  16 . The stator  554  includes a main body  582  having a centrally disposed aperture  584 . The bearing  350  is partially received within the aperture  584  and the motor spindle  28  is received through each, extending into the gear case  18 . The main body  582  may include a radial recess  586  formed into a front face  588  for partially retaining the bearing  350  therein. The stator  554  may include an outer surface  590  having a plurality of stator fins  592  extending therefrom. The plurality of stator fins  592  are preferably positioned at varying pitch angles and lengths for directing airflow out of various openings of the housing  12 . The stator  554  further includes a plurality of holes  594  for receiving screws or bolts  596  therethrough. The bolts  596  fix the stator  554  to the back wall  580  of the gear case  18 . 
   A radial groove  598  is preferably formed into a back face  600  of the main body  582  and forms first and second guide walls  602 ,  604 . The first guide wall  602  of the stator  554  is received into the first gap  570  of the fan  552  and the first guide wall  564  of the fan  552  is received into the radial groove  598  of the stator  554 . Further, the second guide wall  604  of the stator  554  is received into the second gap  574  between the first and second guide walls  564 ,  566  of the fan  552 , whereby the second guide wall  566  of the fan  552  extends over the second guide wall  604  of the stator  554 . 
   A clearance fit may be provided between the engaging features of the fan  552  and stator  554 , whereby the fan  552  freely rotates relative to the stator  554  as it is driven by the motor  26 . Further, the engaging features of the fan  552  and stator  554  provide a labyrinth path  606  therebetween. The labyrinth path  606  inhibits dust, dirt or other debris from traveling too deeply into the various integral components of the LAG  10 . Specifically, the labyrinth path  606  inhibits debris from seeping between clearances in the motor spindle  28 , bushing and stator  554  interfaces, thereby protecting the bearing  350  from such debris. 
   As noted previously, the motor spindle  28  is preferably supported between a pair of bearings  348 ,  350 , including the bearing  350  partially received by the stator  554 . Although the bearings  348 ,  350  may be any type commonly known in the art, in an exemplary embodiment, the bearings  348 ,  350  are preferably open ball bearings. Open ball bearings are less expensive than sealed ball bearings and therefore reduce cost, however, they are prone to attracting dirt, thus inhibiting proper function of the bearings. To prevent this, the bearings  348 ,  350  of the exemplary embodiment each include a cap to prevent dirt or debris from entering the interior of the respective bearings. The above-described labyrinth path  606  between the fan  552  and stator  554  further protects the open bearing from debris. 
   (Felt Cover for Open Ball Bearings) 
   In an alternative embodiment, as shown in  FIG. 31  the bearing  350  is pressed into the aperture  352  by a retention plate  610  fixedly attached to the back wall  580  of the gear case  18 . The retention plate  610  may include a centrally disposed stepped portion  612  having an aperture  614  therethrough. The aperture  614  enables the motor spindle  28  to pass therethrough. A felt ring  616  is provided and seats within the stepped portion  612  of the retention plate  610  between the retention plate  610  and the bearing. The felt ring  616  protects the bearing from dirt or other debris that could pass through a gap  618  between the retention plate  610  and the motor spindle  28 . Such a feature is especially significant if the bearing is an open ball bearing, as described above. 
   (Felt Ring in Gearbox) 
   It is also anticipated that a felt ring  616  may be disposed on the gear case side of the bearing  350 , as shown in  FIG. 32 . The felt ring  616  is retained within a recess  620  formed in a face  622  of the back wall  580  of the gear case  18  between a pinion gear  630  and the back wall  580 . The motor spindle  28  passes through the felt ring  616  and into the gear case  18 . The felt ring  616  prevents grease from the gear case  18  to migrate through clearances between the various internal components and into the field case  16 . 
   Gearbox 
   The gearset  30  of the LAG  10  is disposed within the gear case  18  for translating rotational motion of the motor spindle  28  from a first axis of rotation Q to the second axis of rotation R of the wheel spindle  32 . The second axis of rotation R is generally perpendicular to the first axis of rotation Q. The gearset  30  generally includes a pinion gear  630  and a ring gear or main gear  632 . The pinion gear  630  is fixed for rotation with the motor spindle  28 , which is rotatably driven by the motor  26 . The main gear  632  is fixed for rotation with the wheel spindle  32  and is driven by the pinion gear  630 . The main gear  632  is typically in the form of a bevel gear for meshed engagement with the generally frusto-conical pinion gear  630 . 
   Both the pinion gear  630  and main gear  632  should be sized accordingly to account for the amount of torque transmitted and the gear ratio desired. The higher the torque transmission that is required, the larger the gearset  30  must be, specifically, the pinion gear  630 . To reduce overall manufacturing costs, tool weight and tool efficiency, it is desirable to provide a gearset  30  that is minimal in size and weight while maximizing the amount of torque transmittable therethrough. 
   (Pinion Reinforcing Ring) 
   A pinion assembly  640  is provided, that maximizes the transmittable torque capacity of the gearset  30 . With reference to  FIGS. 33 through 35 , the pinion assembly  640  preferably includes a pinion gear  642  and a reinforcing ring  644 . The pinion gear  642  is generally frusto-conical in shape having spiral gear teeth disposed therearound. The pinion gear  642  includes a centrally disposed cylindrical passage  646  through its length. A bottom face  647  of the pinion gear  642  includes a rectangular notch  648  for keyed interface with a mating component  650  of the motor spindle  28  (illustrated in  FIG. 35 ). In this manner, the pinion gear  642  is fixed for rotation with the motor spindle  28 . 
   The reinforcing ring  644  is press-fit about a first end of the pinion gear  642 , thereby strengthening and enabling the pinion gear  642  to transmit a torque load that is significantly higher than torque loads transmittable through equivalently sized pinion gears. Therefore, the pinion assembly  640  maximizes the torque transmission capacity of the pinion gear  642  without increasing the size of the pinion gear  642 . 
   (Air-cooled Gear Case) 
   As the LAG  10  operates, the interaction between the pinion gear  630  and the main gear  632  results in heat build-up within the gear case  18 . Extreme heat build-up is undesirable in that it affects the performance of the LAG, the operational life of the internal components and discomfort if touched by an operator. As shown in  FIG. 36 , a preferred embodiment of the gear case  18  of the present invention includes a round head portion  660 . The field case  16  includes openings  662  on either side of the gear case  18  whereby each opening  662  includes a forwardly extending wing  664 . Airflow (designated by arrows) induced by the fan  552  is directed out through the openings  662  by the stator  554  and is further directed by the wings  664  to travel about the circumference of the gear case  18 . The air is effectively “pinched” between the wings  664  and the outside of the gear case  18  forcing the air to travel at increased speed across the surface of the gear case  18 . The airflow carries away heat generated within the gear case  18 , thereby cooling the gear case  18 . In this manner, the performance of the LAG  10  is maintained and the operational lives of the internal components are extended. 
   Grinder Wheel 
   As previously discussed, the grinder wheel  34  is selectively fixed for rotation with the wheel spindle  32 . As shown in  FIG. 1 , the grinder wheel  34  is received onto the wheel spindle  32  and may be secured thereto by a nut  670 . The grinder wheel  34  may be removed for several reasons, including LAG  10  maintenance, replacement of a broken or worn grinder wheel  34 , or exchanging the type of grinder wheel  34  used (e.g. fine, coarse). 
   Traditional LAG&#39;s  10  require the use of two tools to remove the grinder wheel  34  from the wheel spindle  32 . One tool is used to prevent the wheel spindle  32  from rotating while the second tool is used to unscrew the nut  670  from the wheel spindle  32 . This method is inefficient in that it requires the use of both hands to operate the tools and therefore, the LAG  10  must lie on the ground or a table or the like. 
   (Radial Spindle Lock with Safety Ramp) 
   With particular reference to  FIGS. 37 through 40 , a first embodiment of a wheel spindle lock mechanism  680  is detailed. The wheel spindle lock mechanism  680  is preferably retained by the gear case  18  and positioned radially relative to the main gear  632 . The wheel spindle lock mechanism  680  enables locking of the wheel spindle  32  by holding the main gear  632  from rotation. 
   The wheel spindle lock mechanism  680  may include a shaft guide  682  retained in an opening  684  of the gear case  18 . The shaft guide  682  may include an arcuate bottom face  686  and a top face  688  comprising three surfaces that intersect to form a generally triangular shape. The triangular top face  688  acts as a key to ensure that the wheel spindle lock mechanism  680  is properly assembled into the opening  684 . The shaft guide  682  further includes a centrally disposed aperture  690 , through which a lock pin  692  is disposed. The lock pin  692  includes a shaft portion  694  ( FIGS. 38 ,  40 ) extending from a cap  696  and is preferably biased radially outward by a spring  698 . The lock pin  692  is slidable within a groove  700  ( FIG. 38 ) of the gear case  18  for engaging the main gear  632 . The spring  698  is positioned between the shaft guide  682  and the cap  696  of the lock pin  692 . A rubber boot  702  preferably covers the lock pin  692  and spring  698 , seating around the shaft guide  682 . The rubber boot  702  seals the wheel spindle lock mechanism  680  and gearset  30  from external dirt and debris and prevents grease leakage. 
   A bottom face  704  of the main gear  632  may include a plurality of ramp and groove features  706  (shown in phantom) for selective engagement with the lock pin  692 . Depending upon the rotational position of the main gear  632  relative to the lock pin  692 , depression of the lock pin  692  causes the end of the lock pin  692  to engage either a ramp  708  or a groove  710  of the main gear  632 . If the lock pin  692  engages a ramp  708 , the grinder wheel  34 , and thus the wheel spindle  32  and main gear  632 , are rotatable until the lock pin  692  engages a groove  710 . As the grinder wheel  34  rotates, the lock pin  692  slides along a ramp  708  until engaging the groove  710 . Once in engagement with the groove  710 , the lock pin  692  prohibits further rotation of the main gear  632 , as long as the lock pin  692  remains depressed. Releasing the lock pin  692  releases the main gear  632  and thus, the main gear  632  is again freely rotatable. 
   (Keyless Blade Clamp) 
   Referencing  FIGS. 41 and 42 , a keyless blade clamp  720  will be described in detail. The keyless blade clamp  720  may include an inner clamp  722  that is rotatable about the wheel spindle  32 . The inner clamp  722  preferably includes a top surface  724  having a pair of grooves  726  formed therein and a bearing surface  728  generally formed as an integral washer. Each groove  726  includes a bottom face  730  and upwardly extending side faces  732 . A cross-pin  734  is also included and is disposed through and fixedly attached to the wheel spindle  32  whereby ends  736  of the cross-pin  734  are received into the grooves  726 . The inner clamp  722  is capable of slight clockwise and counter-clockwise rotation about the wheel spindle  32 , whereby the range of rotation is obstructed by the cross-pin ends  736  contacting the side faces  732  of the grooves  726 . 
   To assemble the grinder wheel  34  onto the wheel spindle  32 , the wheel spindle  32  is initially received through a central aperture  738  of the inner clamp  722  whereby the pin ends  736  seat within the grooves  726 . The grinder wheel  34  is then assembled onto the wheel spindle  32  whereby a top face  740  of the grinder wheel  34  lies adjacent to the bearing surface  728  of the inner clamp  722 . The nut  670 , having a bearing surface  742 , is screwed onto a threaded end  744  of the wheel spindle  32  whereby the bearing surface  742  of the nut  670  lies adjacent to a bottom face  743  of the grinder wheel  34 . Although the nut  670  may be sufficiently tightened, thus providing little to no play of the grinder wheel  34  between the bearing surfaces  728 ,  742  of the inner clamp  722  and nut  670 , repetitive use of the LAG  10  tends to loosen the nut  670 , thereby creating play between the bearing surfaces  728 ,  742 . 
   Activation of the LAG  10  causes the wheel spindle  32  to rotate in a first direction of rotation. In the rotational direction, the cross-pin ends  736  contact one of either side faces  732  of the grooves  726  in the inner clamp  722 . Because the side faces  732  extend upward at an angle, the interface between the cross-pin ends  736  and the side faces  732  cause the inner clamp  722  to travel downward, along the wheel spindle  32  toward the grinder wheel  34 . This is achieved by the side faces  732  “riding along”, or sliding against the cross-pin ends  736 . The downward traveling inner clamp  722  pinches the grinder wheel  34  between the bearing surfaces  728 ,  742 . In this manner, grinder wheel play is eliminated and the nut  670  is subjected to axial pressure thereby prohibiting the nut  670  from becoming loose during repetitive use of the LAG  10 . 
   With respect to  FIGS. 43 through 46 , an alternative embodiment of a keyless blade clamp  720 ′ is provided. The alternative embodiment functions similarly to the first embodiment, described above, for reducing grinder wheel play and prohibiting the nut  670  from loosening during repetitive use of the LAG. 
   The keyless blade clamp  720 ′ preferably includes the wheel spindle  32  having a step  750  formed along its length. A bearing assembly  752  is also included and has an upper housing  754  that abuts the step  750  of the wheel spindle  32  and is fixed for rotation with the wheel spindle  32 . A lower housing  756  of the bearing assembly  752  abuts the top surface  740  of the grinder wheel  34 , frictionally interfacing the top surface  740 . The nut  670  is assembled onto the threaded end  744  of the wheel spindle  32 , thereby securing the grinder wheel  34  between the washer face  742  of the nut  670  and the bearing assembly  752 . 
   The bearing assembly  752  preferably includes the upper housing  754 , a bearing disc  758  and the lower housing  756 . The bearing disc  758  may include a washer shaped disc  760  holding a plurality of ball bearings  762  therearound, whereby the ball bearings  762  are free to rotate. The bearing disc  758  is positioned between the upper and lower housings  754 ,  756 , whereby the plurality of ball bearings  762  ride within grooves  764  of the upper and lower housings  754 ,  756 . As best seen in  FIGS. 45 and 46  each groove  764  of the upper and lower housings  754 ,  756  maintains a generally arcuate shape. 
   As the wheel spindle  32  is caused to rotate via activation of the motor  26 , the upper housing  754  rotates with the wheel spindle  32  whereby the plurality of ball bearings  762  roll along the arcuate grooves  764  of the upper housing  754 . Thus, the plurality of ball bearings  762  travel downward into the arcuate grooves  764  of the lower housing  756 , rolling along the arcuate grooves  764  of the lower housing  756  and forcing the lower housing  756  to rotate with the grinder wheel  34  vis-à-vis the frictional interface. In this manner, the upper and lower housings  754 ,  756  separate from one another (see  FIG. 46 ) reducing grinder wheel play and prohibiting the nut  670  from becoming loose from the wheel spindle  32 . 
   (Spindle Lock) 
     FIGS. 47 through 50  detail first and second preferred embodiments of a spindle lock mechanism  780  that enables easy removal of the grinder wheel  34  from the wheel spindle  32 . Specifically,  FIGS. 47 and 48  show a lever  782  that is pivotally supported by the gear case  18 . The lever  782  preferably includes a cammed surface  784  that slidably interfaces a top surface  786  of a lock-piston  788 . The lock-piston  788  may be slidably disposed through an opening  790  in the gear case  18  and comprises a head  792  and a stem  794 . A spring  796  is disposed about the stem  794  of the lock-piston  788 , immediately below the head  792 , and biases the lock-piston  788  upward, into contact with the cammed surface  784 . 
   The wheel spindle  32  is shown disposed through and fixed for rotation with the main gear  632 . The main gear  632  preferably includes at least one lock-hole  800  disposed therethrough, and radially aligned with the lock-piston  788 . 
   To lock the wheel spindle  32 , thereby prohibiting rotational movement of the wheel spindle  32 , the lever  782  is pivoted from an initial horizontal position, relative to the gear case  18 , to a generally vertical position. As the lever  782  pivots, the cammed surface  784  acts on the lock-piston  788 , pushing the lock-piston  788  downward against the biasing force of the spring  796 . After sufficient displacement of the lock-piston  788 , the stem  794  is received into the lock-hole  800 . The stem  794  prevents the main gear  632  from rotation, further preventing the wheel spindle  32  from rotating. Pivoting the lever  782  to its initial horizontal position enables upward displacement of the lock-piston  788  provided by the biasing force of the spring  796 . With the stem  794  disengaged from the lock-hole  800 , the main gear  632 , and thus the wheel spindle  32  are again free to rotate. 
     FIGS. 49 and 50  detail a lever  810  that may be rotatably attached to the gear case  18  by a screw  812 . A bottom face  814  of the lever  810  preferably includes a protruding detent  816  that is slidably disposed through an arcuate groove  818  within the gear case  18 . The gear case  18  also includes an opening  819 , through which a lock-piston  820  is slidably disposed. The lock-piston  820  includes a head  822  having an upwardly extending detent  824  and a stem  826 . A spring  828  is disposed about the stem  826  of the lock-piston  820 , immediately below the head  822 , and biases the lock-piston  820  upward, into contact with the bottom face  814  of the lever  810 . 
   In a first position, the detent  824  of the lock-piston  820  is in contact with only the bottom face  814  of the lever  810 . However, as the lever  810  rotates to a second position, the detent  816  of the lever  810  slides within the arcuate groove  818 , into contact with the detent  824  of the lock piston  820 , thus pushing the lock piston  820  downward against the biasing force of the spring  828 . Similarly as described above, with reference to  FIG. 48 , the stem  826  of the lock-piston  820  is received into the lock-hole  800  for prohibiting rotational motion of both the main gear  632  and the wheel spindle  32 . Rotation of the lever  810  to its initial position brings the detent  816  of the lever  810  out of contact with the detent  824  of the lock-piston  820 , thus enabling upward displacement of the lock-piston  820  by the spring  828 . In this manner, the lock-piston  820  is disengaged from the main gear  632 , whereby, the main gear  632  and wheel spindle  32  are free to rotate. 
   (Tool-less Wheel Removal) 
   An exemplary embodiment of a tool-less grinder wheel removal mechanism  850  is shown in  FIGS. 51 and 52 . The tool-less grinder wheel removal mechanism  850  preferably includes a lever  852 , a piston  854 , a series of spring washers  856 , a first retainer  858  and a second retainer  860 . The tool-less grinder wheel removal mechanism  850  may be generally disposed within a tubular wheel spindle  32 ′. The wheel spindle  32 ′ may be disposed through and fixedly attached to the main gear  632 . The grinder wheel  34  may be clamped between a clamping surface  862  of the wheel spindle  32 ′ and a corresponding clamping surface  864  of the first retainer  858 . In this manner, the grinder wheel  34  is engaged for rotation with the wheel spindle  32 ′ as the main gear  632  drives the wheel spindle  32 ′. 
   The lever  852  may be rotatably mounted to a top surface  866  of the gear case  18  and includes a cammed surface  868 . The cammed surface  868  slidably interfaces a top face  870  of a pin  872  that upwardly extends from an intermediate piston  874  slidably disposed within an opening  876  of the gear case  18 . The intermediate piston  874  includes a downwardly extending pin  878  that contacts a top surface  880  of the piston  854 . The piston  854  is slidably disposed within a cavity  882  of the wheel spindle  32 ′ and is located between an upper stop ring  884  and the spring washers  856 . The spring washers  856  bias the piston  854  upward within the cavity  882 . 
   The first retainer  858  is disposed through a central opening  886  in the grinder wheel  34  and includes a generally cylindrical opening  888  therethrough. A bottom surface  890  of the first retainer  858  includes a plurality of teeth  892 . The second retainer  860  includes a threaded stem  894  extending from a disc  896 . The disc  896  includes an upper surface  898  having a plurality of teeth  900  that selectively mesh with the teeth  892  of the first retainer  858 . The threaded stem  894  of the second retainer  860  is received through the cylindrical opening  888  of the first retainer  858  and upwards through the spring washers  856 , for threaded engagement with a threaded cavity  902  of the piston  854 . 
   To remove the grinder wheel  34 , the lever  852  is pivoted from a horizontal position to a vertical position relative to the gear case  18 . As the lever  852  pivots, the cammed surface  868  interfaces with the pin  872  to slide the intermediate piston  874  downward within the opening  876 , which further slides the piston  854  downward, against the biasing force of the spring washers  856 . Downward displacement of the piston  854  translates to equivalent downward displacement of the second retainer  860  relative to the first retainer  858 , wherein the teeth  892  of the first retainer  858  and the teeth  900  of the second retainer  860  are removed from meshed engagement with one another. The second retainer  860  may thus be unscrewed from threaded engagement with the piston  854 , thereby enabling removal of the grinder wheel  34 . 
   To assemble the grinder wheel  34  to the LAG  10 , the threaded stem  894  of the second retainer  860  is inserted through the cylindrical opening  888  of the first retainer  858  and upwards through the wheel spindle  32 ′, into threaded engagement with the piston  854 . The second retainer  860  is threaded to a sufficient depth into the piston  854  by gripping and rotating the disc  896  of the second retainer  860 . Once sufficiently threaded, the lever  852  is pivoted from the vertical position back to the horizontal position. As the lever  852  pivots, the cammed surface  868  relieves downward force on the intermediate piston  874 , thus enabling upward travel of both the intermediate piston  874  and the piston  854  by the upward biasing force of the spring washers  856 . As a result, the piston  854  pulls upward on the second retainer  860 , through the first retainer  858 , thereby meshing the teeth  892 ,  900  of the first and second retainers  858 ,  860 . 
   (Tool-less Wheel Removal) 
   With reference to  FIGS. 53 and 54 , an alternative embodiment of a tool-less grinder wheel removal mechanism  920  will be described in detail. The tool-less grinder wheel removal mechanism  920  preferably includes a thumbwheel  922 , a piston  924 , a tension spring  926  and a pulling retainer  928  and is disposed within a generally tubular wheel spindle  32 ′. The wheel spindle  32 ′ is disposed through and fixedly attached to the main gear  632 . The grinder wheel  34  is clamped between a clamping surface  930  of the wheel spindle  32 ′ and a corresponding clamping surface  932  of the pulling retainer  928 . In this manner, the grinder wheel  34  is engaged for rotation with the wheel spindle  32 ′ as the main gear  632  drives the wheel spindle  32 ′. 
   The thumbwheel  922  includes a threaded extension  934  for threaded engagement with a threaded opening  936  in the gear case  18  and a formed circumferential surface  938  for easy grip. An end  940  of the threaded extension  934  is rounded and contacts a top surface  942  of the piston  924 . A stop ring  944  seats within a groove  946  of the threaded extension  934  for prohibiting disengagement of the thumbwheel  922  with the gear case  18 . The piston  924  is slidably disposed within a cavity  948  of the wheel spindle  32 ′ and is positioned between an upper stop ring  949  and the tension spring  926 . However, the piston  924  is prohibited from rotating relative to the wheel spindle  32 ′ by a spline interface  951  with an internal surface  953  of the wheel spindle  32 ′. The tension spring  926  is disposed between a bottom surface  955  of the piston  924  and a lower stop ring  957 , whereby the tension spring  926  biases the piston  924  upward within the wheel spindle  32 ′. The pulling retainer  928  includes a threaded extension  959  that is threadably engaged with a cavity  961  of the piston  924  and further includes a formed circumferential surface  963  for easy grip. 
   To remove the grinder wheel  34 , the thumbwheel  922  is rotated generally clockwise wherein the threaded extension  934  travels downward within the threaded opening  936 . As the threaded extension  934  travels downward, the rounded end  940  pushes the piston  924  downward against the biasing force of the tension spring  926 . Subsequently, the pulling retainer  928  travels downward relative to the wheel spindle  32 ′ thus relieving clamping pressure between the clamping surfaces  930 ,  932  of the wheel spindle  32 ′ and the pulling retainer  928 . With the clamping pressure relieved, the pulling retainer  928  is rotatable for disengagement from the piston  924 , and thus, the grinder wheel  34  may be removed from the LAG  10 . 
   To assemble the grinder wheel  34  to the LAG  10 , the pulling retainer  928  is inserted through the central opening  886  of the grinder wheel  34  and is threaded into the cavity  961  of the piston  924 . Once the pulling retainer  928  is sufficiently threaded within the cavity  961 , the thumbwheel  922  is rotated in a generally counter-clockwise direction. As the thumbwheel  922  rotates, the threaded extension  934  travels upward within the opening  936 , thus relieving downward force on the piston  924 . The tension spring  926  biases the piston  924  upward further carrying the pulling retainer  928  upward, again providing a clamping force between the wheel spindle  32 ′ and the pulling retainer  928 . The upward bias of the tension spring  926  provides tensile engagement between the pulling retainer  928  and the piston  924 , thus prohibiting the pulling retainer  928  from inadvertent disengagement with the piston  924 . 
   (Tool-less Wheel Removal) 
   With reference to  FIGS. 55-57 , a second alternative embodiment of a tool-less grinder wheel removal mechanism  950  will be described in detail. The tool-less grinder wheel removal mechanism  950  preferably includes a thumbwheel  952 , a piston  954 , a retainer plate  956 , a tension spring  958  and a pulling retainer  960 . The piston  954  retains the plate  956  and the tension spring  958  are disposed within the generally tubular wheel spindle  32 ′. The wheel spindle  32 ′ is disposed through and fixedly attached to the main gear  632 . The grinder wheel  34  is clamped between a clamping surface  962  of the wheel spindle  32 ′ and a corresponding clamping surface  964  of the pulling retainer  960 . In this manner, the grinder wheel  34  is engaged for rotation with the wheel spindle  32 ′ as the main gear  632  drives the wheel spindle  32 ′. 
   The thumbwheel  952  may be rotatably mounted to a top surface  966  of the gear case  18  and includes a formed circumferential surface  968 , for easy grip, and a cammed bottom surface  970 . The thumbwheel  952  is rotatable about an axis that is generally offset from and parallel to the axis of rotation of the wheel spindle  32 ′. The cammed bottom surface  970  of the thumbwheel  952  slidably interfaces a rounded end  972  of a pin  974  that is slidable within an opening  976  of the gear case  18 . An opposing end  977  of the pin  974  is rounded and contacts a top surface  978  of the piston  954 . A stop ring  980  seats within a groove  982  of the pin  974  for prohibiting removal of the pin  974  from the gear case  18 . 
   The piston  954  is slidably disposed within a cavity  984  of the wheel spindle  32 ′ and is positioned immediately above the retainer plate  956 . The retainer plate  956  is prohibited from rotating relative to the wheel spindle  32 ′ by a spline interface  986  with an internal surface  988  of the wheel spindle  32 ′. The tension spring  958  may be disposed between a bottom surface  990  of the retainer plate  956  and a lower stop ring  992 , thereby biasing both the piston  954  and the retainer plate  956  upward. 
   The pulling retainer  960  is selectively engageable with the retainer plate  956  and includes an extension  994  having lock pins  996 . As best seen in  FIG. 57 , the extension  994  is receivable through a centrally disposed opening  998  of the retainer plate  956  that includes slots  1000 . The lock pins  996  align with the slots  1000  enabling the extension  994  to pass through the opening  998 . Once through, the pulling retainer  960  is rotatable relative to the retainer plate  956  wherein the lock pins  996  are out of alignment with the slots  1000  and the extension  994  is prohibited from disengagement with the retainer plate  956 . 
   To remove the grinder wheel  34  from the LAG  10 , the thumbwheel  952  is rotated wherein the cammed bottom surface  970  acts on the pin  974 , pushing the pin  974  downward within the opening  976 . As the pin  974  travels downward, the rounded end  972  pushes the piston  954  downward against the biasing force of the tension spring  958 . Subsequently, the pulling retainer  960  travels downward relative to the wheel spindle  32 ′ thus relieving clamping pressure between the clamping surfaces  962 ,  964  of the wheel spindle  32 ′ and the pulling retainer  960 . With the clamping pressure relieved, the pulling retainer  960  is rotatable for aligning the lock pins  996  of the extension  994  with the slots  1000  of the retainer plate  956 . Thus, the pulling retainer  960  is disengagable from the retainer plate  956  and the grinder wheel  34  is removable from the LAG  10 . 
   To assemble the grinder wheel  34  to the LAG  10 , the pulling retainer  960  is inserted through the central opening  886  of the grinder wheel  34  and is positioned such that the lock pins  996  align with the slots  1000 . Once the extension  994  of pulling retainer  960  is sufficiently through the opening  998 , the pulling retainer  960  is rotatable wherein the lock pins  996  and slots  1000  are out of alignment. The thumbwheel  952  is again rotated and the biasing force of the tension spring  958  ultimately pushes the pin  974  upward against the cammed surface  970 . As the thumbwheel  952  rotates, the cammed surface  970  enables upward travel of the pin  974  within the opening  976 . The upward biasing of the tension spring  958  pushes the retainer plate  956  upward, thus pulling the pulling retainer  960  upward, again providing a clamping force between the wheel spindle  32 ′ and the pulling retainer  960 . The upward bias of the tension spring  958  provides tensile engagement between the pulling retainer  960  and the retainer plate  956 , thus prohibiting the pulling retainer  960  from inadvertent disengagement with the retainer plate  956 . 
   (Double Wall Gear Case/Air Bleed System) 
   With reference to  FIGS. 40 and 58 , a double-wall gear case  1010  will be described in detail. The double-wall gear case  1010  preferably includes first and second gear case portions  1010   a ,  1010   b . First gear case portion  1010   a  includes a gear well  1012  defined by an inner wall  1014  and a circumferential wall  1015  formed within the first gear case portion  1010   a . An airflow cavity  1016  may also be included within the first gear case  1010   a  and is defined by an upper wall  1018  and an outer wall  1020  of the gear case portion  1010   a . The outer wall  1020  of the first gear case portion  1010   a  includes a plurality of baffled openings  1022 . The airflow cavity  1016  is in fluid communication via an opening  1024  with the fan  552 , described in detail above, whereby air driven by the fan  552  flows through the air flow cavity  1016  and out the plurality of baffled openings  1022 . The driven air vents through the plurality of baffled openings  1022 , thus cooling the gear case  1010 . 
   As the LAG  10  operates, increased heat and pressure forces grease out any available openings of the gear case  1010 . To compensate for this, traditional gear wells are large in profile for providing a large expansion chamber. The large profile gear wells, although inhibiting forced grease flow out of the gear case  18 , increase the size of the LAG  10 . The gear well  1012  of the double wall gear case  1010  is generally lower in profile than traditional wells and therefore provides a lower volume expansion chamber. To account for increased pressure within the gear well, an air bleed system is provided. 
   Again referencing  FIG. 40 , a first exemplary embodiment of an air bleed system  1030  is detailed. The air bleed system  1030  includes a bleed hole  1032  formed in the outer wall  1020  of the double-wall gear case  1010 . The bleed hole  1032  is disposed immediately above a cavity  1034  that retains the wheel spindle  32  and a wheel spindle bushing (not shown), and is generally conical in shape, tapering upwards until apexing at the bleed hole  1032 . Developing pressure within the gear well  1012  is relieved as pressurized air seeps through the wheel spindle  32  and wheel spindle bushing interface (not shown) and out the bleed hole  1032 . The conical shape of the bleed hole  1032  is designed to inhibit outward pressurized grease flow. The location of the bleed hole also reduces the risk of gears flinging grease into the opening, blocking air exhaust. Centrifugal forces tend to keep grease away from the exhaust port when the port is located on the spindle bearing hub. 
   With reference to  FIG. 59 , a second exemplary embodiment of an air bleed system  1040  is detailed. The air bleed system  1040  includes a channel  1042  formed along a length of a wheel spindle cavity  1044 . A bleed hole  1046  is also included, which exits back into an upper chamber  1048  of the double-wall gear case  1010 . A porous material  1050  seats within an upper portion of the cavity  1044  between the channel  1042  and the bleed hole  1046 . The porous material inhibits grease from exiting the bleed hole  1046  while enabling outward flow of pressurized air. 
   As discussed above, the air bleed system  1030 ,  1040  enables pressure release from within the gear well  1012 , thus reducing the chance of outward forced grease flow. In this manner, a smaller well profile is achievable. As a result of the smaller profile, grease is maintained in closer proximity to the internal components of the gearbox thus extending gear component life and reducing heat build up. Also, a smaller gear case is achievable enabling the design of smaller tools, reducing both material cost and weight. Further, the air cavity provides improved cooling of the gearbox, thus improving the operational life of the SAG  10 . 
   Wheel Guard 
   Again referencing  FIG. 1  the gear case  18  may further include a wheel guard mount  1060  extending downward and through which, the wheel spindle  32  is disposed. A wheel guard  1100  is attachable to the wheel guard mount  1060  for protecting an operator from the spinning grinder wheel  34 . The wheel guard  1100  generally includes a wheel shield  1102  and an upward extending, circular flange  1104  having a gap  1106  therethrough. The wheel guard mount  1060  is received into the wheel guard flange  1104  for clamping the wheel guard  1100  to the gear case  18 . The wheel guard  1100  covers an arcural portion of the grinder wheel  34  and is adjustable about the grinder wheel  34 . Additionally, grinder wheel  34  sizes may vary and therefore each size requires a corresponding wheel guard  1100 . 
   (Guard Clamping Mechanism) 
     FIGS. 60 and 61  detail an exemplary embodiment of a quick-release mechanism  1120  for a wheel guard  1100 . The quick-release mechanism  1120  preferably includes an open clamping ring  1122  having a straight wall  1124  formed at a first end and a curved second end  1128 . A link  1130  is included for selectively linking the first end  1124  of the clamping ring  1122  to the curved second end  1128 . The link  1130  may include a lever  1132  pivotally attached at an intermediate point  1134  to a first end of an intermediate link  1138 . A second end of the intermediate link  1138  is pivotally connected to the end of a bolt  1142  that is disposed through the straight wall  1124  of the clamping ring  1122 . A first end of the lever  1132  includes a roller  1146 . 
   As best seen in  FIG. 61 , the wheel guard mount  1060  of the gear case  18  is received into the clamping ring  1122 . The roller  1146  is positioned to rest in the curved second end  1128  of the clamping ring  1122  with the lever  1132  positioned generally perpendicular to the clamping ring  1122 . To tighten the clamping ring  1122  about the wheel guard mount  1060 , the lever  1132  is depressed towards the clamping ring  1122  until it curves with, or is substantially parallel to the clamping ring  1122 , thus tightening the clamping ring  1122  onto the wheel guard mount  1060 . In this manner, the wheel guard  1100  may quickly and easily be replaced or adjusted. 
   (Improved Wheel Guard) 
   An alternative embodiment of the quick-release mechanism, designated as  1120 ′, is detailed in  FIGS. 62 and 63 . The quick-release mechanism  1120 ′ includes an open clamping ring  1150  having mounting features  1152 ,  1154  formed at either end. A first end  1152  of the clamping ring  1150  preferably includes a threaded screw  1158  extending therefrom. The screw  1158  threads into a threaded pivot  1160  that is retained between a pair of intermediate links  1162 ,  1164 . The intermediate links  1162 ,  1164 , are pivotally attached to a lever  1174  along an intermediate length of the lever  1174 . An end  1176  of the lever  1174  is pivotally attached to the mounting feature  1154 . 
   An “M” shaped bracket  1180  is welded to the clamping ring  1150  on an opposite side as the lever  1174 . The “M” shaped bracket  1180  includes a curved bracket portion  1182  with outward extending arms  1184 ,  1186  disposed on either end. The ends of the outward extending arms  1184 , 1186  contact an alignment feature  1188  extending downward from the gear case  18 . The contact between the arms  1184 ,  1186  of the “M” shaped bracket  1180  and the alignment feature  1188  ensures that the quick-release mechanism  1120 ′ remains in a constant position, relative to the gear case  18 , as the wheel guard  1100  rotates for adjustment. It is also anticipated that the length of the extending arms  1184 ,  1186  of the “M” shaped bracket  1180  can be used as a key to ensure that proper sized wheel guards  1100  are used with their corresponding angle grinders. 
   The circular flange  1104  may further include an inwardly extending tab  1190  that rides in a groove  1192  ( FIG. 1 ) formed around the wheel guard mount  1060 . The tab  1190  and groove  1192  interface retains the wheel guard  1100  on the wheel guard mount  1060  as the wheel guard  1100  rotates thereabout for adjustment. 
   To tighten the clamping ring  1150  about the wheel guard mount  1060 , the lever  1174  is depressed towards the clamping ring  1150  until it curves with, or is substantially parallel thereto. This causes the clamping ring  1150  to constrict, further constricting the circular flange  1104 . The gap  1106  in the circular flange  1104  enables constricting motion of the circular flange  1104 . In this manner, the wheel guard  1100  may quickly and easily be replaced or adjusted. 
   (Wheel Guard) 
   With particular reference to  FIGS. 64 and 65 , a second alternative embodiment of an adjustable and removable wheel guard is designated as  1100 ′. The wheel guard  1100 ′ includes a flange  1200 , around which a compliant ring  1202  may be disposed. The compliant ring  1202  is an open ring having first and second ends  1204 ,  1206 , respectively, forming first and second radially extending walls  1208 ,  1210 , respectively. The first and second walls  1208 ,  1210  each include an aperture  1212 ,  1214 , respectively. 
   The wheel guard mount  1060  of the gear case  18  includes a ratchet surface  1216  formed around its circumference. Additionally, a groove  1218  is formed around the circumference of the wheel guard mount  1060  adjacent to the ratchet surface  1216 . The wheel guard mount  1060  is received through the compliant ring  1202  which is tightened thereabout by a bolt  1220  inserted through the apertures  1212 ,  1214  of the first and second walls  1208 ,  1210 . A spring  1222  is also included and is disposed about the bolt  1220 , between the first wall  1208  and a bolt head  1224 . The bolt  1220  is tightenable by way of threaded engagement with a nut  1226 . As the bolt  1220  is tightened, the compliant ring  1202  is subsequently tightened about the wheel guard mount  1060 . The spring  1222  provides slight relief of the tightening force of the compliant ring  1202 . 
   An adjustment clip  1228  may be disposed around an external circumference of the compliant ring  1202 . The adjustment clip  1228  includes an upward curving first end  1230 , a tab  1232  extending radially inward, centrally disposed first and second clip arms  1234 ,  1236  and a ratchet tab  1238  formed at a second end  1240 . The clip arms  1234 ,  1236  are received into first and second hooks  1242 ,  1244  of the compliant ring  1202 , thereby holding the adjustment clip  1228  against the external circumference of the compliant ring  1202 . The tab  1232  is received through an aperture  1246  in the compliant ring  1202  and seats Within the groove  1218  of the wheel guard mount  1060 . The tab  1232  and groove  1248  interface prevents the wheel guard  1100 ′ from being pulled off of the wheel guard mount  1060 . The ratchet tab  1238  is similarly received through an aperture  1250  in the compliant ring  1202  and interfaces with the ratchet surface  1216  of the wheel guard mount  1060 . In this manner, the wheel guard  1100 ′ is able to adjust rotationally relative to the wheel guard mount  1060 , in a single rotational direction. The tightened compliant ring  1202  enables deliberate adjustment of the wheel guard, given sufficient exerted force. Thus, the wheel guard  1100 ′ is both removable and adjustable without requiring auxiliary tools. 
   (Wheel Guard) 
   Referencing  FIGS. 66-68 , a third alternative embodiment of an adjustable and removable wheel guard  1100 ″ is shown. The wheel guard  1100 ″ includes a flange  1268 , around which a spring ring  1270  is disposed. The spring ring  1270  is preferably fixedly attached to the flange  1268  of the wheel guard  1100 ″ and is sprung around the wheel guard mount  1060  of the gear case  18 . The wheel guard mount  1060  includes a groove  1192  ( FIG. 68 ) formed about an external circumference and a relief notch  1274 . A tab  1276  of the spring ring  1270  is slidably disposed within the groove  1192 . The tab  1276  and groove  1192  interface prohibits the wheel guard  1100 ″ from being pulled from the wheel guard mount  1060 . A semi-circular rubber sleeve  1278  is also provided, through which the spring ring  1270  is disposed. The biasing force of the spring ring  1270 , in concert with the frictional force provided between the rubber sleeve  1278  and the wheel guard mount  1060  secures the wheel guard  1100 ″ in a fixed position relative to the gear case  18 . 
   Rotational adjustment of the wheel guard  1100 ″ relative to the gear case  18  is provided by a lever mechanism  1280 . The lever mechanism  1280  includes a lever arm  1282  pivotally attached to the wheel guard  1100 ″. The lever arm  1282  includes a first end  1284  defining a cam surface  1286  and is biased in a closed position by a coil spring  1288 . In the closed position, the cam surface  1286  is out of contact with a curved end  1290  of the spring ring  1270 . The lever arm  1282 , is pivotable against the biasing force of the spring  1288 , towards an open position. As the lever arm  1282  pivots toward the open position, the cam surface  1286  slidably engages the curved end  1290  of the spring ring  1270 , pushing the spring ring  1270  open, thus relieving pressure around the wheel guard mount  1060 . With the pressure about the wheel guard mount  1060  relieved, the wheel guard  1100 ″ is rotationally adjustable therearound. 
   To remove the wheel guard  1100 ″ from the wheel guard mount  1060 , the lever arm  1282  is actuated to the open position, and the wheel guard  1100 ″ is rotated until the tab  1276  aligns with the relief notch  1274 . This is best shown in  FIG. 68 . Once aligned, the wheel guard  1100 ″ can be pulled free from engagement with the wheel guard mount  1060  as the tab  1276  is disengaged from the groove  1192  through the relief notch  1274 . In this manner, the wheel guard  1100 ″ is both removable and adjustable without requiring any auxiliary tools. 
   (Tool-less Adjustable Guard) 
   Yet another alternative embodiment of an adjustable wheel guard  1100 ′″ is detailed in  FIGS. 69 and 70 . The wheel guard  1100 ′″ is rotatably disposed about the wheel guard mount  1060  and includes an upward extending locator pin  1300 . The locator pin  1300  may be selectively receivable into one of a plurality of holes  1302  formed in a semi-circular pattern on a bottom face  1304  of the gear case  18  (best shown in  FIG. 70 ). The wheel guard  1100 ′″ also includes an upward extending blocking tab  1306  that interfaces with one of either two formed structures  1308 ,  1310  of the gear case  18  for limiting the range of rotation of the wheel guard  1100 ′″ about the wheel guard mount  1060 . The formed structures  1308 ,  1310  are disposed on either end of the semi-circular hole pattern. 
   The wheel guard  1100 ′″ is retained on the wheel guard mount  1060  by a spring pack  1312  and a retention nut  1314 . The retention nut  1314  is screwed onto an intermediate threaded portion  1316  of the wheel spindle  32 , whereby the spring pack  1312  and wheel guard  1100 ′″ are disposed and retained between the retention nut  1314  and the wheel guard mount  1060 . The spring pack  1312  biases the wheel guard  1100 ′″ up against the wheel guard mount  1060 , biasing the locator pin  1300  into engagement with one of the plurality of holes  1302 . The spring pack  1312  includes first and second washers  1318 ,  1320  having a spring washer set  1322  disposed therebetween. The first washer  1318  seats against an inside face  1324  of the wheel guard  1100 ′″ and the second washer  1320  is grounded against the retention nut  1314 . 
   To rotationally adjust the wheel guard  1100 ′″ about the wheel guard mount  1060 , force is applied to the wheel guard  1100 ′″, axially in the direction of the wheel spindle axis. In this manner, the wheel guard  1100 ′″ is depressed against the bias force of the spring pack  1312 , disengaging the locator pin  1300  from the hole  1302 , whereby the wheel guard  1100 ′″ is rotationally adjustable about the wheel guard mount  1060 . To lock the wheel guard  1100 ′″ in a desired position, downward force is relieved from the wheel guard  1100 ′″ and the spring pack  1312  again biases the locate pin  1300  into engagement with one of the plurality of holes  1302 . 
   Miscellaneous 
   (Rubber Bump) 
   An exemplary embodiment of the LAG  10 , as shown in  FIG. 1 , includes a bumper  1350  located on a top face  1352  of the housing  12 . The bumper  1350  is shown attached to the gear case  18 , however, it is anticipated that the bumper  1350  may be positioned anywhere along the housing  12 , as desired. The bumper  1350  is preferably made from rubber, plastic or other material that is lightweight and elastic. The bumper  1350  provides a support structure to lie the LAG  10  against when not in use and easily pick-up the LAG  10  for use. 
   The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.

Technology Classification (CPC): 7