Abstract:
A key-operated ignition lock has a housing configured to protectively shield an electrical switch. An operating knob has a tubular body that extends through a first passage defined by the housing, and is rotable therein between a plurality of angular positions including on “off” position. The tubular body defines a second passage wherein elements including a key-receiving plug of a lock mechanism are journaled for rotation between “locked” and “unlocked” positions. Alignable bores formed 1) in the tubular body, 2) in a locking plate that surrounds the tubular body, 3) in the plug, and 4) in a barrel that surrounds the plug support an end-to-end arrangement of pins that permit a suitably configured key to be inserted into the plug only when the knob is in its “off” position, and to permit the knob to be rotated out of its “off” position only when the key is removed from the plug. To concurrently retain the knob in the first passage and the lock mechanism in the second passage, slots are formed in over-lying side portions of the tubular body of the knob and in the barrel of the lock mechanism to receive a retaining bar that is connected to the housing. A retractable bolt carried at the rear of the tubular body extends from the tubular body to connect the knob to the electrical switch when the lock is “unlocked,” and retracts when the lock is “locked” to disconnect the knob from the switch.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a key operated lock that, while designed to accommodate special ignition switch needs of high quality motorcycles, also offers features that, taken alone or in combination, are well suited for use in other key operated lock applications. More particularly, the present invention relates to features of a key operated lock having a “hand positioned operator” or “knob” that is rotatable between or among a plurality of detented angular positions, wherein the knob has a tubular body that carries a lock mechanism having a barrel that journals a key-receiving plug for separate rotation between “locked” and “unlocked” positions when a properly configured key is inserted into the plug, with novel features including a unique way the knob and the lock mechanism are retained in a protective housing of the lock by utilizing a retaining bar that is closely received in a slip-fit within aligned, transversely extending slots formed in overlying side regions of the tubular body of the knob and the barrel of the lock mechanism, and unique ways: 1) of permitting the key to be inserted into and removed from the plug when the plug is in either of its “locked” and “unlocked” positions, but only when the knob is in its “off” position; 2) of permitting the knob to be rotated out of its “off” position but only when the key has been removed from the plug; and, 3) of providing a retractable bolt carried at the rear of the tubular body of the knob which extends to drivingly connect the knob to an electrical switch for operating the switch in response to rotation of the knob when the lock is “unlocked,” and which retracts when the lock is “locked” to disconnect the knob from the switch. 
     2. Prior Art 
     Ignition locks for motorcycles and other engine powered equipment often are provided with a so-called “hand positioned operator” or “knob” that is rotatable between or among a plurality of detented angular positions to operate an electrical switch. When the lock is “unlocked” a driving connection is established between the knob and the electrical switch. When the lock is “locked” the knob is disabled from operating the switch. Ignition locks of this type typically permit their knobs to move between or among angular positions that are labeled “accessory on,” “off” and “engine on”—or, more simply “ACC,” “OFF” and “ON.” 
     Some ignition locks of this type can be defeated by utilizing a wrench or other tool to force their knobs to rotate to “on” positions. To provide greater security, others of these ignition locks are provided with mechanisms for rendering their knobs “free wheeling” when the locks are locked so that rotation of their knobs between or among various angular positions will not cause operation of associated electrical switches. 
     In automobiles and trucks where little vibration of the ignition lock is likely to be encountered, it is accepted practice for the ignition key to remain in the key-receiving opening of the ignition lock while the vehicle is in operation. However, in motorcycles and other types of engine operated equipment where vibration of the ignition lock may be prevalent, it is desirable for the ignition key to be removed during vehicle operation so that the key will not vibrate out of the key-receiving opening and become lost. To ensure that the ignition key of a motorcycle is removed rather than left in place during operation of the motorcycle&#39;s engine, it has been proposed that the knob of the ignition lock be prevented from moving out of its “off” position unless and until the ignition key is withdrawn from the key-receiving opening. 
     One type of key operated lock mechanism that has received relatively little use in vehicle ignition locks is disclosed in U.S. Pat. No. 5,485,735 issued Jan. 23, 1996 to Timothy P. Laabs et al, and also in U.S. Pat. No. 5,531,084 issued Jul. 2, 1996 to Timothy P. Laabs et al (referred to hereinafter as the “Dimpled Key Lock Patents”), the disclosures of which are incorporated herein by reference. In accordance with the teachings of the Dimpled Key Lock Patents, two or more rows of spring projected tumblers having convexly rounded inner ends are received in dimple-like recess formations that are provided in at least two of the four side surfaces of a key of generally rectangular cross-section to enable a correctly dimpled key to operate a cam that is located at the rear of the lock mechanism. In preferred practice, the present invention makes use of selected features of key operated lock mechanisms of the type disclosed in the Dimpled Key Lock Patents. 
     SUMMARY OF THE INVENTION 
     The present invention provides an ignition lock that is especially well suited for use with high quality motorcycles, which includes novel features that also may be utilized to good advantage in other key operated lock applications. 
     One need addressed by the preferred practice of the present invention is the provision of a secure type of ignition lock that will prevent a motorcycle from being operated unless and until its ignition key has been withdrawn from a key-receiving opening of the lock—a lock that has a “free wheeling” operating knob that will move without operating electrical switches when the lock is “locked.” To accommodate this need, 1) an operating knob is provided that can be moved out of its “off” position only when the ignition key has been removed from the key receiving opening; 2) a lock mechanism is provided that enables the key to be removed when a key-receiving plug of the lock mechanism is rotated to either of its “locked” and “unlocked” positions; and, 3) a disconnect mechanism is provided to decouple the electrical switch from the knob when the lock is locked to thereby render the knob “free wheeling” to prevent the lock from being defeated by forcing the knob to an “on” position when the lock is locked. 
     Another need addressed by the present invention is the provision of a relatively simple means of retaining in secure assembled relationship a plurality of concentrically nested relatively rotatable lock components such as a knob which is rotatable between a plurality of angular positions relative to a housing that supports the knob, and a key-receiving plug of a lock mechanism that is journaled by a barrel of the lock mechanism for rotation between locked and unlocked positions relative to the knob which houses the lock mechanism. A novel approach employed by the present invention to accommodate this need calls for aligned transversely extending slots to be provided in overlying side regions of a tubular barrel of the knob and of the barrel of the lock mechanism to receive in a slip fit therein a retaining bar that is connected to the housing. By this novel arrangement, the needs faced by the knob and the plug to be independently rotatable through limited ranges of movement can be accommodated while providing a lock that is easy to assemble, easy to lubricate and easy to disassemble when maintenance so requires. 
     To accommodate the need to prevent rotation of the knob out of its “off” position except when the key has been removed, and to prevent key insertion except when the knob is in its “off” position, a key-engageable pin arrangement is provided that extends into the key-receiving opening to block key insertion except when the knob is in its “off” position. The same aligned bores that house the key-engageable pin arrangement also cooperate with the key-engageable pin arrangement to block rotation of the knob out of its “off” position at all times except when the key is removed from the plug. 
     To provide a disconnect to selectively couple the key operated lock to the electrical switch that enables or disables the ignition system of the vehicle, a radially extensible-retractable bolt is provided near the rear end region of the tubular body of the knob that extends into a notch of a rotatable sleeve to drivingly connect the knob to the electrical switch when the lock is “unlocked,” and that withdraws to drivingly disconnect the knob from the electrical switch when the lock is “locked.” This extensible-retractable bolt is caused to extend and retract due to its being drivingly engaged by a cam that is defined by the rear end region of the plug of the lock mechanism. When the plug is in its locked position, the cam causes the bolt to retract; and, when plug is in its unlocked position, the cam causes the bolt to extend. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other features and a fuller understanding of the invention may be had by referring to the following description and claims taken in conjunction with the accompanying drawings, wherein: 
     FIG. 1 is a perspective view of an ignition lock embodying the preferred practice of the present invention, with key operated components of the lock “locked” and with a knob of the lock in its “off” position; 
     FIG. 2 is a sectional view thereof as seen from a plane indicated by a line  2 — 2  in FIG. 1; 
     FIG. 3 is a rear elevational view of the housing of the lock, but with other components of the lock shown in cross-section as seen from a plane indicated by a line  3 — 3  in FIG. 2; 
     FIG. 4 is a rear elevational view similar to FIG. 3, but with other lock components shown in cross-section as seen from a plane indicated by a line  4 — 4  in FIG. 2; 
     FIGS. 5 and 6 are exploded perspective views of selected components of the ignition lock; 
     FIG. 7 is a perspective view showing rear portions of the lock housing, with a locking plate of the lock removed, and with portions of other components of the lock broken away to permit underlying features to be seen; 
     FIG. 8 is a sectional view as seen from a plane indicated by a line  8 — 8  in FIG. 6; 
     FIG. 9 is an enlargement of a central portion of the sectional view of FIG. 2; 
     FIG. 10 is a sectional view as seen from a plane indicated by a line  10 — 10  in FIG. 9, showing the detenting of the knob of the lock in its OFF position; 
     FIG. 11 is a sectional view similar to FIG. 10 but showing the detenting of the knob of the lock in its ACC position; 
     FIG. 12 is a sectional view similar to FIGS. 10 and 11 but showing the detenting of the knob of the lock in its ON position; 
     FIG. 13A is a sectional view as seen from a plane indicated by a line A—A in FIG. 9, with components of the lock positioned as they arrange themselves when the knob is in its OFF position, when the lock mechanism is LOCKED, and when the key is INSERTED; 
     FIG. 13B is a sectional view as seen from a plane indicated by a line B—B in FIG. 9, with the components of the lock positioned as in FIG. 13A; 
     FIG. 14A is a sectional view as seen from a plane indicated by a line A—A in FIG. 9, with components of the lock positioned as they arrange themselves when the knob is in its OFF position, when the lock mechanism is UNLOCKED, and when the key is INSERTED; 
     FIG. 14B is a sectional view as seen from a plane indicated by a line B—B in FIG. 9, with the components of the lock positioned as in FIG. 14A; 
     FIG. 15A is a sectional view as seen from a plane indicated by a line A—A in FIG. 9, with components of the lock positioned as they arrange themselves when the knob is in its OFF position, when the lock mechanism is LOCKED, and when the key is REMOVED (it being noted that any differences between component orientations of FIGS. 13A and 15A results from the presence of an INSERTED key in FIG. 13A, and the absence of a key in FIG.  15 A); 
     FIG. 15B is a sectional view as seen from a plane indicated by a line B—B in FIG. 9, with the components of the lock positioned as in FIG. 15A; 
     FIG. 16A is a sectional view as seen from a plane indicated by a line A—A in FIG. 9, with components of the lock positioned as they arrange themselves when the knob is in its OFF position, when the lock mechanism is UNLOCKED, and when the key is REMOVED (it being noted that any differences between component orientations of FIGS. 3.4A and  16 A results from the presence of an INSERTED key in FIG. 14A, and the absence of a key in FIG.  16 A); 
     FIG. 16B is a sectional view as seen from a plane indicated by a line B—B in FIG. 9, with the components of the lock positioned as in FIG. 16A; 
     FIG. 17A is a sectional view as seen from a plane indicated by a line A—A in FIG. 9, with components of the lock positioned as they arrange themselves when the knob is in its ACC position, when the lock mechanism is LOCKED, and when the key is REMOVED; 
     FIG. 17B is a sectional view as seen from a plane indicated by a line B—B in FIG. 9, with the components of the lock positioned as in FIG. 17A; 
     FIG. 18A is a sectional view as seen from a plane indicated by a line A—A in FIG. 9, with components of the lock positioned as they arrange themselves when the knob is in its ACC position, when the lock mechanism is UNLOCKED, and when the key is REMOVED; 
     FIG. 18B is a sectional view as seen from a plane indicated by a line B—B in FIG. 9, with the components of the lock positioned as in FIG. 18A; 
     FIG. 19A is a sectional view as seen from a plane indicated by a line A—A in FIG. 9, with components of the lock positioned as they arrange themselves when the knob is in its ON position, when the lock mechanism is LOCKED, and when the key is REMOVED; 
     FIG. 19B is a sectional view as seen from a plane indicated by a line B—B in FIG. 9, with the components of the lock positioned as in FIG. 19A; 
     FIG. 20A is a sectional view as seen from a plane indicated by a line A—A in FIG. 9, with components of the lock positioned as they arrange themselves when the knob is in its ON position, when the lock mechanism is UNLOCKED, and when the key is REMOVED; and, 
     FIG. 20B is a sectional view as seen from a plane indicated by a line B—B in FIG. 9, with the components of the lock positioned as in FIG.  20 A. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, an ignition lock embodying the preferred practice of the present invention is indicated generally by the numeral  100 . The ignition lock  100  provides a key lockable device for operating one or more electrical switches for controlling the supply of electricity to the engine of a motorcycle or other form of engine powered vehicle, and for controlling the supply of electricity to accessories of such a vehicle, for example radios, lights, horns, signalling devices, and the like. 
     In providing an overview of the ignition lock  100 , reference principally will be made to FIGS. 2 and 5 wherein major components and assemblies of the ignition lock  100  are depicted. Referring to FIGS. 2 and 5, an electrical switch assembly operated by the lock  100  is indicated generally by the numeral  50 . Although commercially available switches of a wide variety of types may be operated by the lock  100 , in preferred practice the lock  100  is used with electrical switches of a type that are specially manufactured for Excelsior-Henderson motorcycles—switches that have an appearance quite similar to that indicated by the numeral  50  in FIGS. 2 and 5. 
     The switch  50  has an operating sleeve  60  that is supported by a switch housing  70 . The sleeve  60  extends coaxially about an imaginary rotation axis  80 , and is rotatable clockwise and counterclockwise about the axis  80 . Protectively supported within the housing  70  are suitable sets of switch contacts (not shown) for making and breaking electrical circuits that direct electrical power to the engine and accessories of a motorcycle. The sleeve  60  defines a groove or slot  90  that extends along an upper interior side of the sleeve  60  in a direction that parallels the axis  80 . An “off” position of the switch  50  obtains when the slot  90  is at the twelve o&#39;clock position depicted in FIGS. 2 and 5. An “accessories on” or ACC position of the switch  50  obtains when the sleeve  60  is rotated counterclockwise approximately forty-five degrees (i.e., to an angular position indicated by the angle A in FIGS.  11  and  16 A). An “engine on” or ON position of the switch  50  obtains when the sleeve  60  is rotated clockwise approximately forty-five degrees (i.e., to an angular position indicated by the angle B in FIGS.  12  and  18 A). 
     Referring still to FIGS. 2 and 5, components of the lock  100  that provide for operation of the switch  50  in the manner just described include: a housing  200 ; a “hand positioned operator” or “knob”  300  that is supported by the housing  200  for rotation about the rotation axis  80  and that defines a tubular body  310  which extends rearwardly and into the sleeve  60  of the switch  50 ; a key lock mechanism  400  that is housed within the knob  300  and that provides a barrel  405  that houses a plug  410  which is rotatable about the axis  80  between “locked” and “unlocked” positions and which defines a key-receiving opening  420 ; a suitably configured key  500  for insertion into the key-receiving opening  420  for locking and unlocking the lock mechanism  400  by rotating the plug  410  between the “locked” and “unlocked” positions; a retainer bar  600  for retaining the housing  200 , the knob  300  and the lock mechanism  400  in assembled relationship; an annular locking plate  700  for cooperating with an end-to-end arrangement of pins (described later in conjunction with FIGS. 13A,  14 A,  15 A,  16 A,  17 A,  18 A and  19 A wherein these pins are depicted) that are carried within alignable bores defined by the knob  300 , the lock mechanism  400  and the locking plate  700  to add a set of desirable performance features to the lock  100 ; and an extensible-retractable bolt  800  that is movably supported by the tubular body  310  of the knob  300  toward the rear of a tubular body  310  for selectively extending into and withdrawing from the slot or groove  90  of the switch  50  to selectively establish and disestablish a driving connection between the knob  300  and the switch sleeve  60  to permit the knob  300  to operate the switch  50  when the lock mechanism  400  is unlocked. Other features and details of all these and other components of the ignition lock  100  will be described in the paragraphs that follow. 
     Referring to FIGS. 1,  2  and  7 , the housing  200  has something of a keystone configuration, with its shape defined by a complexly configured front wall  210  that joins at its periphery with a top wall  212 , a bottom wall  214  and side walls  216 ,  218  to surround a protected space  220 . The front wall  210  can be thought of as providing a “mounting panel” having a front face  222  and a rear face  224  that surround a central opening or “first passage”  230  that provides access to the protected space  220 . 
     As is best seen in FIG. 6, the opening  230  has three opposed sets of V-shaped recesses formed in its opposite sides. A first set of V-shaped recesses  240  located at twelve and at six o&#39;clock positions about the axis  80  correspond to an OFF position of the knob  300 , and to the above-described OFF orientation of the sleeve  60  of the switch  50 . A second set of V-shaped recesses  250  is located counterclockwise about the axis  80  relative to the first set of V-shaped recesses  240  (i.e., at an angular orientation indicated by the angle A in FIGS. 11 and 16A) that corresponds to an ACC position of the knob  300  and to the ACC position of the switch sleeve  60  (as described above). A third set of V-shaped recesses  260  is located clockwise about the axis  80  relative to the first set of V-shaped recesses  240  (i.e., at an angular orientation indicated by the angle B in FIGS. 12 and 18A) that corresponds to an ON position of the knob  300  and to the ON position of the switch sleeve  60  (as described above) Referring to FIGS. 7,  9  and  10 , a cylindrical formation  320  of the knob  300  is journaled for rotation about the axis  80  by opposite left and right sides of the housing opening  230  (and by other portions of the housing opening  230  located between various ones of the recesses  240 ,  250 ,  260 ). In this manner, the knob  300  is rotatably mounted by the housing  200 . Springs  270  and detent plungers  280  are carried in opposite end regions of a hole  312  (see FIGS.  6  and  9 - 12 ) that extends diametrically through the cylindrical formation  320 . When the knob  300  is in its OFF position, the plungers  280  are biased by the springs  270  into engagement with the V-shaped recesses  240  as shown in FIGS. 9 and 10. When the knob  300  is in its ACC position, the plungers  280  are biased by the springs  270  into engagement with the V-shaped. recesses  250 , as shown in FIG.  11 . When the knob  300  is in its ON position, the plungers  280  are biased by the springs  270  into engagement with the V-shaped recesses  260 , as shown in FIG.  12 . By this arrangement, the knob  300  is “detented” in a manner that tends to bias it toward one or another of its OFF, ACC or ON positions. 
     Referring to FIGS. 5,  6  and  7 , the retaining bar  600  and the annular locking plate  700  are rigidly connected to the housing  200  by a pair of threaded fasteners  605 . The fasteners  605  have enlarged heads  615  that are received in stepped-diameter holes  715  formed through the annular locking plate  700 . Threaded bodies of the fasteners  605  extend through aligned holes  625  formed in opposite end regions of the retaining bar  600 , and thread into aligned holes (not shown) that open through the back face  224  of the housing  200 . 
     Referring to FIGS. 5 and 6, the retaining bar  600  is notched, as indicated by the numeral  635 , to prevent central portions of the retaining bar  600  from engaging the plug  410  of the lock mechanism  400  and from extending into the key-receiving slot  420  of the plug  410  (to ensure that the retaining bar  600  does not obstruct insertion, removal and rotary movements of the key  500 ). 
     Referring to FIG. 6, a radially extending bore  750  is provided in the annular locking plate  700  that does not go all of the way through the locking plate  700 —and a spring  770  and an outer pin  760  are provided for insertion into the bore  750 . Referring to FIG. 13A, while the bore  750  goes all of the way through one side of the annular locking plate  700 , it goes only part-way through the opposite side of the annular locking plate  700  so as to define a short, closed-ended region  755  that opens toward the tubular body  310  of the knob  300 . The spring  770  and the outer pin  760  are carried in the short bore portion  755 . 
     Referring to FIGS. 2 and 6, the knob  300  provides enlarged, hand-graspable lugs  330  that are located on opposite sides of a central passage  340 . The central passage  340  presents a circular cross-section as it extends well into the tubular body  310  of the knob  300 . Toward the rear of the tubular body  310 , the diameter of the central passage  340  is substantially reduced, as is indicated by the numeral  342  in FIG.  8 . The reduced diameter rear end region  342  of the passage  340  intersects a transversely extending passage  380  that slidingly carries the extensible-retractable boll  800 . 
     Referring to FIGS. 8 and 9, a transversely extending wall  344  provides an abrupt juncture between the relatively large diameter front end region of the passage  340  and the reduced diameter rear end region  342  of the passage  340 . Extending forwardly a short distance from the wall  344  is a flat-surfaced projection  346  which is engaged by a mating flat-surfaced recessed region  446  (see FIG. 9) formed at the rear of the barrel  405  of the lock mechanism  400 . The engagement of the flat surfaces  346 ,  446  is what prevents the barrel  405  from rotating relative to the knob  300  about the rotation axis  80 . When the lock mechanism  400  is installed in the knob passage  340 , the engagement of the flat surfaces  346 ,  446  permits the tubular barrel  405  to act as though it were formed integrally with the tubular body  310  of the knob  300 —in the sense that no relative rotation is permitted to take place between the tubular barrel  405  of the lock mechanism  400  and the tubular body  310  of the knob  300 . 
     The retaining bar  600  serves the dual purpose of retaining the lock mechanism  400  in the central passage  340  of the knob  300 , and retaining the knob  300  in place on the housing  200  (with the cylindrical portion  320  of the knob  300  journaled in the housing opening  230 ). Referring to FIGS. 4,  7  and  10 , these purposes are accomplished by providing aligned slots  390 ,  490  in overlying side regions of the tubular body  310  of the knob  300 , and of the tubular barrel  405  of the lock mechanism  400 . The slots  390 ,  490  closely receive central portions of the retaining bar  600  in a slip-fit that permits concurrent rotation of the tubular body  310  and the tubular barrel  405  relative to the housing  200  about the rotation axis  80 . The slots  390 ,  490  cut transversely through much of the cross-section of the tubular body  310  and through much of the cross-section of the tubular barrel  405 —enough, in fact, to ensure that the tubular body and barrel  310 ,  405  are able to rotate through about a quarter-turn movement, as required to permit the knob  300  to move from the ACC position (i.e., the angular position A depicted in FIGS. 11 and 16A) through the OFF position (i.e, the twelve o&#39;clock position depicted in FIGS. 1-7,  9 ,  10 ,  12 A,  13 A,  14 A and  15 A) to the ON position (i.e., the angular position B depicted in FIGS.  12  and  18 A). 
     Referring to FIGS. 3 and 6, the purpose served by the lock mechanism  400  is to position (in response to operation of the lock mechanism by the key  500 ) a cylindrical-shaped cam  415  which is carried at the rear end of the plug  410 —and to thereby cause the extensible retractable bolt  800  to move within the knob passage  380  to extend a reduced diameter end region  810  of the bolt into the groove  90  of the switch sleeve  60  to drivingly connect the knob  300  and the switch  50 , and to withdraw the end region  810  of the bolt  800  from the groove  90  of the switch sleeve  60  into the passage  380  of the knob  300  to disestablish a driving connection between the knob  300  and the switch  50 . In FIG. 3, the retracted position of the bolt  800  is shown in solid lines, and the extended position of the bolt  800  is shown in phantom. 
     When the bolt  800  is retracted, the lock mechanism  400  is “locked,” and vice versa. The retracted position of the bolt  800  is depicted in FIGS. 5,  13 A,  15 A,  17 A and  19 A. When the bolt is retracted, the end region  810  is withdrawn from the sleeve groove  90 , whereby no driving connection is provided between the knob  300  and the switch  50 , hence the switch sleeve  60  does not rotate out of its OFF position when the knob  300  rotates to its ACC position (see FIGS.  17 A and  18 A), and does not rotate out of its OFF position when the knob  300  rotates to its ON position (see FIGS.  19 A and  20 A). 
     When the bolt  800  is extended, the lock mechanism  400  is “unlocked,” and vice versa. The extended position of the bolt  800  is depicted in FIGS. 2,  9 ,  14 A,  16 A,  18 A and  20 A. When the bolt is extended, the end region  810  extends into the sleeve groove  90  to establish a driving connection between the knob  300  and the switch  50  that causes the switch sleeve  60  to rotate to its ACC position when the knob  300  rotates to its ACC position (see FIG.  18 A), and that causes the switch sleeve  60  to rotate to its ON position when the knob  300  rotates to its ON position (see FIG.  20 A). 
     Referring to FIG. 6, the cam  415  effectively provides an “eccentric crank” that extends into a circumferentially extending groove  815  of the bolt  800  for moving the bolt  800  up and down in the knob passage  380  in response to quarter-turn rotations of the cam  415  by the plug  410  of the lock mechanism  400 . A “down” position of the cam  415  that causes the bolt  800  to be retracted when the lock mechanism  400  is “locked” is depicted in FIGS. 13B,  15 B,  17 B and  19 B. An “up” position of the cam  415  that causes the bolt  800  to extend when the lock mechanism  400  is “unlocked” is depicted in FIGS. 14B,  16 B,  18 B and  20 B. 
     While the lock mechanism  400  may take any of a variety of commercially available forms (i.e., a number of cylindrical lock assemblies are commercially available from a variety of manufacturers that are designed to provide quarter-turn positioning of a rearwardly extending cam such as the cam  415 ), a preferred type of lock mechanism is one that is disclosed in the above-referenced Dimpled Key Lock Patents, the disclosures of which are incorporated herein by reference. A lock mechanism of this type has a plug such as the plug  410  that is journaled by a surrounding barrel such as the barrel  405  (portions of which are surrounded by a tubular shell such as the shell  413 ) to house a plurality of tumblers and springs (such as the depicted tumblers  423  and springs  433 ) for cooperating with a suitably configured key such as the key  500  to permit the key, when inserted into a key-receiving slot of the plug, to cooperate with the tumblers to rotate the plug between locked and unlocked positions that are separated by a quarter turn of rotation. Inasmuch as the preferred arrangement and the operation of components of the lock mechanism  400  are disclosed in the referenced Dimple Key Lock Patents, and inasmuch as the character of the springs and tumblers that interact to permit and prohibit relative rotation of the plug  410  and the barrel  405  are outside the scope of the present invention, the disclosure of the referenced Dimpled Key Lock Patents need not be repeated here. 
     Referring to FIG. 13A, a bore  455  is provided in the plug  410 , a bore  465  is provided in the barrel  405 , and a bore  355  is provided in the tubular body  310  of the knob  300 —and the bores  355 ,  455  and  465  align with the closed-ended bore  755  in the locking plate  700  when the lock mechanism  400  is locked. The bores  355 ,  455 ,  465 ,  755  align regardless of whether the key  500  is inserted into the key-receiving opening  420  as depicted in FIG. 13A, or whether the key  500  is removed as depicted in FIG. 15A so long as the plug  410  is in its locked position and so long as the knob  300  is in its OFF position. 
     Housed within the plug bore  455  is an inner pin  456  for engaging a side surface of the key  500  when the key  500  is inserted into the key-receiving opening  420 . 
     Carried within the bores  465 ,  355  of the tubular barrel  405  and the tubular body  310  is a dual-diameter central pin  466  which has a relatively small inner diameter for extending part of the way into the plug bore  455  (when the key  500  is removed as is shown in FIG.  15 A), and a relatively larger diameter for extending into the aligned bores  465 ,  755  (when the key  500  is inserted into the key-receiving opening  420  as is shown in FIG.  13 A). 
     In FIGS. 13A,  14 A,  15 A,  16 A,  17 A,  18 A,  19 A and  20 A, the interaction of a set of end-to-end pins that are carried in aligned bores of the plug  410 , the barrel  405 , the tubular body  310  of the knob  300 , and in the locking member  700  is depicted. In FIGS. 13B,  14 B,  15 B,  16 B,  17 B,  18 B,  19 B and  20 B, the resulting associated positions of the cam  415  and the bolt  800  are depicted. Each of the “B” FIGURES is associated with one of the “A” FIGURES. For example, the cam and bolt positions that are depicted in FIG. 13B result from the component positions that are depicted in FIG. 13A; the cam and bolt positions shown in FIG. 14B result from the component positions shown in FIG. 14A; and so on. The following table summarizes the eight different component orientations that are depicted in FIGS.  13 A through  20 B: 
     
       
         
               
               
               
               
               
               
               
             
           
               
                   
               
               
                 FIGURES 
                 Key 500 
                 Knob 300 
                 Plug 410 
                 Cam 615 
                 Bolt 800 
                 Switch 
               
               
                   
               
             
             
               
                 13A-13B 
                 INSERTED 
                 OFF 
                 LOCKED 
                 DOWN 
                 RETRACTED 
                 OFF 
               
               
                 14A-14B 
                 INSERTED 
                 OFF 
                 UNLOCKED 
                 UP 
                 EXTENDED 
                 OFF 
               
               
                 15A-15B 
                 WITHDRAWN 
                 OFF 
                 LOCKED 
                 DOWN 
                 REFRACTED 
                 OFF 
               
               
                 16A-16B 
                 WITHDRAWN 
                 OFF 
                 UNLOCKED 
                 UP 
                 EXTENDED 
                 OFF 
               
               
                 17A-17B 
                 WITHDRAWN 
                 ACC 
                 LOCKED 
                 DOWN 
                 RETRACTED 
                 OFF 
               
               
                 18A-18B 
                 WITHDRAWN 
                 ACC 
                 UNLOCKED 
                 UP 
                 EXTENDED 
                 ACC 
               
               
                 19A-19B 
                 WITHDRAWN 
                 ON 
                 LOCKED 
                 DOWN 
                 RETRACTED 
                 OFF 
               
               
                 20A-20B 
                 WITHDRAWN 
                 ON 
                 UNLOCKED 
                 UP 
                 EXTENDED 
                 ON 
               
               
                   
               
             
          
         
       
     
     What FIGS. 13A and 14A interesting illustrate is that the ignition lock  100  permits relatively little to take place when the key  500  is inserted into the key receiving slot  420 . The large diameter outer end region of the central pin  466  bridges between the passages  355 ,  755  of the tubular body  310  and the locking member  700  when the key  500  is inserted—and this completely prevents the knob  300  from being rotated out of its OFF position when the key  500  is inserted. 
     Also to be noted is that the only condition under which the key  500  can be inserted into the key-receiving opening  420  is when the knob  300  is OFF. Only then the knob  300  is OFF do the passages  755 ,  465 ,  455  align to permit the key to push the pins  466 ,  760  radially outwardly to a point where a shear line between the pins  466 ,  760  will align with the juncture between the tubular body  310  and the inner diameter of the locking member  700  to enable the tubular body  310  of the knob  300  to rotate relatives to the locking member  700  (hence relative to the housing  200 ). 
     What is illustrated by the switch status summary hat appears in the last column of the table just above is that the switch  50  remains OFF except under two very specific circumstances when it is operated at its ACC and ON positions in response to rotation of the knob  300  to its ACC and ON positions, respectively. These two conditions occur only when the lock plug  410  is unlocked. As will be noted, when the lock plug  410  is locked, the knob  300  is “free wheeling” in the sense that it can be rotated between its ACC, OFF and ON positions without causing corresponding movement of the switch sleeve  60 . 
     The knob  300  is, in fact, free to rotate between its ACC, OFF and ON positions at any time when the key  500  is withdrawn from the key-receiving opening  420 . When the key is withdrawn, either the inner end of the pin  466  extends into the key-receiving opening  420  as is depicted in FIGS. 16A,  18 A and  20 A, or the inner end of the pin  466  presses against the inner pin  456  to press the inner end of the inner pin  456  into the key-receiving opening  420  as is depicted in FIGS. 15A,  17 A and  19 A—and, either of these occurrences will permit the shear line between the adjacent pins  466 ,  760  to align with the juncture of the tubular body  310  and the locking member  700  so the tubular body  300  is permitted to rotate relative to the housing  200 . 
     As will be apparent from the foregoing description taken in conjunction with the table presented just above, the accompanying drawings and the appended claims, the present invention provides quite a sophisticated lock for high quality motorcycles or other engine powered equipment that will prevent operation of such a vehicle when the key is inserted, and that will provide an operating knob that is “free wheeling” when locked to ensure that the lock is not defeated by forcefully moving the knob to operate an associated ignition switch. 
     While such terms as “horizontally extending,” “front,” “rear,” “forwardly facing,” “rearwardly facing,” “left,” “right,” “up,” “down” and the like are utilized herein, it will be understood that such terms are used merely to aid the reader in referring to features in the orientations in which they are depicted in the accompanying drawings, and are not to be construed as limiting the scope of the claims that follow. 
     While the invention has been described with a certain degree of particularity, it will be understood that the present disclosure of the preferred embodiment has been made only by way of example, and that numerous changes in the details of construction and the combination and arrangement of elements can be resorted to without departing from the true spirit and scope of the invention as hereinafter claimed. It is intended that the patent shall cover, by suitable expression in the claims, such features of patentable novelty exist in the invention disclosed.