in fig1 door locking and unlocking is implemented by a lock mechanism 1 in response to the pivotal movement of a lever 2 mounted on the mechanism . a knob 3 is pivotally mounted to the lever 2 to manually operate it up and down . reference numeral 4 designates an electrical door lock operating mechanism . for simplicity of explanation the mechanism cover has been removed in fig1 . a motor 6 is disposed below a casing 5 , and an output shaft of the motor extends into the casing . a centrifugal clutch 7 is mounted on the output shaft . as seen in fig2 the centrifugal clutch mechanism 7 includes a rotatable disc 7b secured to the motor shaft 6a and four radial partition plates 7a mounted on the disc . sector - shaped weight members 7c are slidably accomodated in the quadrant spaces defined by the disc 7b , the partition plates 7a and a surrounding cylindrical cup member 7d . the cup member 7d is freely rotatable about the output shaft 6a of the motor , and the outer circumference of each weight member centrifugally contacts or separates from the inner periphery of the cup member . when the motor 6 is energized by a switch ( not shown ) the disc 7b together with the four partition plates 7a begins to rotate . the weight members 7c also rotate , and move radially outwardly to centrifugally engage the inner wall of the cup member 7d , to thus rotate the latter . fig3 shows an alternate centrifugal clutch mechanism including a rotatable disc member 7b &# 39 ; secured to the motor shaft 6a and a pair of pins 7a &# 39 ; upstanding from the disc . slots formed in centrifugal weight members 7c &# 39 ; are slidably engaged with the pins 7a &# 39 ; and the output shaft 6a . the functioning of the fig3 construction is identical to that of fig2 . referring again to fig1 a reduction mechanism gear 9 engages a pinion 8 axially secured to the cylindrical cup member 7d , and a smaller gear 32 is coaxially mounted on the gear 9 . the smaller gear 32 engages a sector gear 10 pivotally mounted on shaft 10a fixed to the casing 5 . the flattened lower end of an actuating rod 11 is pivotally coupled to the sector gear 10 by a connecting pin 12 . the flattened upper end of the rod 11 has an elongaged slot 13 in which a pin 14 secured to the end of the lever 2 is slidingly disposed whereby the lever 2 may be moved up and down by the actuating rod 11 . the length of the slot 13 is substantially equal to the length of the stroke l of the pin 14 necessary to actuate the lock mechanism 1 via the lever 2 . a torsion spring 15 is disposed around the pivot shaft 10a to bias the sector gear 10 toward a neutral position , as shown in fig1 . the ends of the spring 15 are freely engaged with the sides of a plate member 16 fixed to the sector gear 10 , and extend into a pair of holes or slots 17a , 17b . when the sector gear 10 is in a neutral position the center of the slot 13 is positioned at a level c , which bisects the stroke l of the lever 2 . the pin 14 is positioned at the upper end 13a of the slot 13 when the door is unlocked , and at the lower end 13b of the slot 13 when the door is locked . when the motor 6 is deenergized after forward or reverse rotation , the sector gear 10 is restored to its neutral position by the biasing force of the torsion spring 15 . a second torsion spring 18 is disposed around the pivot shaft 10a and its protruding ends engage posts 19 , 19 &# 39 ; at the corners of the casing 5 . the spring 18 functions as a damper , whereby the sector gear 10 engages the upstanding ends of the spring to widen it and thus decrease the striking force of the sector gear against the casing 5 . rubber dampers may also be substituted for the spring 18 . with this structure , when the door is unlocked , the operator can manually lock it by simply pushing down on the knob 3 and with it the lever 2 , whereby the pin 14 moves from the upper end 13a of the longitudinal slot to the lower end 13b thereof . the operator can also manually unlock the door by pulling up on the knob 3 and lever 2 , whereby the pin 14 travels from the lower end 13b of the slot 13 to the upper end 13a thereof . in both cases , since the pin 14 moves only between the upper and lower ends of the slot 13 , i . e ., over the distance l , the movement of the lever 2 is not transmitted to the actuating rod 11 , whereby manual operation is not coupled to and does not drive the reduction gear mechanism . in automatic operation , in order to lock the unlocked door the motor shaft 6a is driven counterclockwise ( ccw ) to centrifugally engage the weight members 7c with the inner wall of the cup member 7d , whereby the sector gear 10 is pivoted downwardly or ccw from its neutral position through the reduction gear 9 . this pulls down the actuating rod 11 , the pin 14 which engages the upper end 13a of the slot 13 , as shown at position a in fig4 and with it the lever 2 . one end of the torsion spring 15 engages the lower end of the hole 17b , while the other end of the spring is moved along the hole 17a by reason of its engagement with the plate member 16 . upon completion of the door locking the edge of the sector gear 10 is in contact with the side wall of the casing 5 , which prevents the sector gear from further rotation . when the motor 6 is deenergized the sector gear is restored to its neutral position by the torsion spring 15 , to thereby raise the slot 13 of the actuating rod 11 to its neutral position ( as shown by the solid lines in fig4 ), whereat the pin 14 contacts the lower end 13b of the slot . owing to the disengagement of the centrifugal clutch 7 , the motor 6 is not rotated during the movement of the sector gear 10 to its neutral position , whereby such movement is easily and rapidly accomplished by the biasing force of the spring 15 . on the other hand , in order to unlock the locked door , the motor is driven clockwise ( cw ) to pivot the sector gear 10 upwardly or cw through the clutch and reduction gear mechanism , to thereby move the actuating rod 11 upwardly . when the door is unlocked the slot 13 is in the position shown at b in fig4 . when the motor 6 is deenergized , the centrifugal clutch is disengaged and the sector gear 10 is biased back to its neutral position by the torsion spring 15 , which moves the slot 13 to the neutral position at which the pin 14 contacts the upper end 13a of the slot . any impact that occurs when the sector gear 10 strikes the casing 5 is absorbed by frictional slippage in the clutch 7 . since the distance moved by the actuating rod 11 due to the movement of the sector gear 10 is equal to the stroke l between the door lock and unlock positions , the stroke of the gear 10 is determined to be substantially equal to the length l from the neutral position thereof to either the downward or upward limit of travel . for manufacturing purposes , however , the sector gear swing is designed to be somewhat larger than the stroke l . fig5 shows another embodiment of the invention , wherein the reference numerals designate the same structural elements shown in fig1 . instead of providing an elongated slot 13 at the upper end of the actuating rod 11 as shown in fig1 however , in fig5 an elongated slot 13 &# 39 ; is provided in the sector gear 10 &# 39 ;. the upper end of the actuating rod 11 &# 39 ; is thus pivotally connected to the lever 2 by a pin 20 , while the lower end thereof is provided with a pin 14 &# 39 ; which is slidably disposed in the slot 13 &# 39 ;. the remaining structure and operation is identical to that of fig1 except for the relocation of the motor 6 and reduction gear 9 . in the above two embodiments the elongated slot is positioned either in the upper end of the actuating rod 11 or in the sector gear 10 &# 39 ;. alternatively , the slot may be positioned in the lower end of the actuating rod , or directly in the lever 2 . that is , the slot may be disposed at any place in the connecting linkage between the lever 2 and the sector gear 10 . fig6 shows another embodiment of the invention , wherein one end of the lever 2 is pivotally mounted to the lock mechanism 1 by a shaft 1a , and the other end of the lever 2 is connected to a manual operating knob 3 . a sector - shaped linkage member 21 is also pivotally mounted on the shaft 1a , and an actuating rod 11 &# 34 ; is pivotally connected thereto . an upper stop projection 22 and a lower stop projection 23 are provided on the linkage member 21 , the distance between them being substantially equal to the stroke l of the lever 2 beteen the lock and unlock positions , whereby the lever 2 may slide between the upper and lower projections 22 , 23 . the structure and functioning of this embodiment is otherwise identical to that of the former embodiments . alternatively , the manual knob 3 may be connected to the sector - shaped linkage member 21 , and the actuating rod 11 connected to the lever 2 . fig7 and 8 show other embodiments of the torsion spring 15 for biasing the sector gear 10 to its neutral position . in fig7 a torsion spring 15 &# 39 ; is disposed around the bearing of the pivot shaft 10a , and the upstanding ends of the spring 15 &# 39 ; are inserted in an elongated hole 24 . the widening of the spring 15 &# 39 ; is prevented by a plate 16 &# 39 ; attached to the sector gear 10 . in this case , only a single hole is required as opposed to the two holes 17a , 17b in the embodiment of fig1 . in fig8 a torsion spring 15 &# 34 ; straddles the sector gear 10 , and its ends are inserted in the holes 17a &# 39 ; and 17b &# 39 ;. with this arrangement the plate 16 and 16 &# 39 ; is not required . instead of providing a torsion spring 15 , 15 &# 39 ;, or 15 &# 34 ; as in fig1 fig7 and fig8 respectively , a coil spring 25 may be disposed around the actuating rod 11 , as shown in fig9 . the spring 25 is disposed in a housing 26 defined in the upper portion of the casing 5 , and the upper and lower ends of the housing have openings to accommodate the actuating rod 11 . upper and lower washers 27 , 28 having larger diameters than the rod openings are disposed in the housing to compress the spring 25 , and upper and lower stops 29 , 30 are fixed to the actuating rod just outside of the upper and lower washers 27 , 28 , respectively . in operation , when the sector gear 10 is moved upwardly by the energization of the motor , the washer 27 is stopped by the upper wall of the spring housing 26 while the washer 28 is moved upwardly by the stop 30 to compress the spring 25 . when the motor is deenergized , the sector gear 10 is pivoted back to its neutral position by the restoring force of the spring 25 . fig1 shows a supplemental feature of the invention which may be employed with any of the preceding embodiments , according to which a compression spring 31 is attached to the lever 2 at point 31a . the biasing force of the spring 31 acts in the direction d as shown in fig1 . when the pin 14 on the lever 2 , the pivot point 2a , and the point 31a are in straight alignment , as shown in fig1 , no force is exerted on the lever 2 since the spring 31 does not provide any rotational moment about the pivot point 2a . if the lever 2 is pivoted slightly up or down by the actuating rod , the biasing force of the spring 31 reinforces the pull of the actuating rod 11 , but such additional force is largely negated or offset by the frictional forces generated in the lock mechanism 1 when the lever 2 is within an angular range p . if the lever 2 exceeds the range p , however , due to the movement of the actuating rod 11 , its rotation is then automatically continued by the force of the spring 31 within a range designated q to positively lock or unlock the door . the rotation of the motor shaft can therefore be minimized , and limited to a range designated p 1 whereat the spring force becomes sufficiently larger than the frictional resistance of the lock mechanism to sharply complete the locking or unlocking operation .