550,731. Door locking systems for motor vehicles. TERNSTEDT MANUFACTURING CO. Sept. 19, 1941, No. 12052. Convention date, Jan. 21. [Class 44] In an electrically controlled locking system for motor vehicles in which each door lock has means whereby the outside handle may be rendered effective or ineffective to retract the bolt, both front door locks are arranged to act as master locks or as subsidiary locks so that either front door lock may be used to control all the other locks. Fig. 1 shows a lock of known kind adapted for use as a front door lock in the system. The bolt 1 shot by spring 16 is retracted by outside handle follower 5 acting on a pivoted lever 4 biased clockwise by spring 28 disposed about its pivot. The lower end of lever 4 is pivotally connected to a thrust member 2 to which sliding motion to the night is imparted by operation of the handle. The free end of member 2 is slidably guided between lugs 11, 12 on a vertically slidable member 10 whereby said end may be raised or lowered by the pivoted armature 9 common to and rocked by a pair of selectively energized electromagnets 8, 36, one end of the armature being suitably connected to the lower end of member 10. The armature is held in each of its two positions against accidental movement by a spring 50. In the raised effective or release position shown, the end of member 2 abuts against a projection 3 on the bolt to effect retraction, but in the lower ineffective or locking position, as in Fig. 5, the end slides idly below the projection so that the bolt is not retracted by the outside handle. A key-operated member 13 is also provided to move the armature to release position, by outside key operation. If the door be slammed when member 2 is in its lower door-locking position the inward movement of the bolt restores the parts to the release position by engagement of shoulder 6 on the bolt with cam surface 7 on member 2, to avoid the operator unintentionally locking himself out. To prevent this action and ensure locking of the door the outside handle must be operated to move member 2 to the right and held in this position during closure of the door to keep cam 7 beyond the reach of shoulder 6. When the handle is then released member 2 remains in its lower position with the outside handle ineffective. The upper end of member 10 engages a pin 14 which operates a main switch 15. Normally, also, the upper end 25 of lever 4 bears against a push-button 24 to hold a subsidiary switch 22 open, this switch being closed by spring 23 when the outside handle is operated. The subsidiary locks used on the rear doors differ from the above only in that the master switch 14, 15, key-operated member 13, catch 50, and locking solenoid 8 are omitted, the armature being normally held in locking position by a spring 20, Fig. 5, which shows the circuit arrangements for a four-door car with the two front door locks at the left and the rear door locks at the right, all being shown in door-locking condition. In a convenient position on or near each front door a pair of push-button or other switches is mounted, one of each pair (29 or 30) being for door release, and the other (31 or 32) for door locking. To effect release the operator closes either of switches 29, 30 thereby closing a circuit from battery B through magnet 36 of the corresponding front door lock, so that members 2, 10 of that lock are raised and the outside handle of that lock becomes effective. At the same time switch 15 of that lock is closed, thus preparing circuits from the battery to the subsidiary switches of the other three locks so that, when the outside handle of any of these locks is operated, the subsidiary switch of that lock closes, completing circuit through the release magnet of that lock, further movement of the handle then retracting the bolt. The rear locks are returned to locking position by springs 20 when their handles are released, but the front door locks remain in release position unless either of switches 31, 32 is closed, thus completing circuits from the battery through both magnets 8.