Key operated lock
United States Patent Schweizer et al.  
 [ Apr. 29, 1975 [5 KEY OPERATED LOCK |.2ss I854 United Kingdom 70/355 [75] inventors: Paul Edward Schweizer, Marion,  
 wili zg g xzg i t fsg z i Primary Examiner-Albert G. Craig, 11&#39;. wammk a Ind Attorney, Agent, or F [rm-Barry H. Freedman [73] Assignee: Bell Telephone Laboratories,  
  Incorporated, Murray Hill, NJ. [22] Filed: Jan. 31, 1974 [57] ABSTRACT PP 433,290 An improved key operated lock inhibits lock picking by preventing movement of the levers when the gates U s C i l l I formed therein can bfi felt the fence. The levers are [5 1 1 Int. Cl I i l Eos&#39;b 2H0 held stationary by a lever lock which engages the lever [58] Field of I34 355 tips whenever the fence is drawn toward the curved 6 edge portion of the levers by rotation of the cam, as in a picking attempt. In normal operation with a key, the [56] Reerences cited levers are properly positioned before being locked by the lever lock, so that rotation of the cam moves the UNITED STATES PATENTS bolt to its withdrawn position as the fence enters the 75,854 3/l868 Burton 70/355 gateg FOREIGN PATENTS OR APPLICATIONS 2980 1853 United Kingdom 70/355 2 Claims, 8 Drawing Figures l4 l0! II J 0 O as IO3 I02 0 Pmmmmsm SHEET 3 BF 6 m Qk PATENTEBAFRZS I975 SHEEI 5 BF 6 oNT PATENTEDAPRZSBYS SiiiEi ii if FIG. 8  
 KEY OPERATED LOCK BACKGROUND OF THE INVENTION l. Field of the Invention The present invention relates generally to lever locks and, more particularly. to the incorporation in such locks of means to prevent picking or other unauthorized entry techniques.  
 2. Description of the Prior Art As more fully described in US. Pat. No. 3.402.581. issued to P. E. Schweizer et al. on Sept. 24, I968, a key operated, lever type lock typically employs a stack of pivotally mounted leaf-like levers or tumblers. Each lever has a deep notch or gate extending inwardly in a more or less radial direction from its curved outer periphery. As the key is turned, each of the key notches engages the side edge of a corresponding one of the levers causing it to pivot through a related arc of travel until all of the lever gates are aligned in the path of a projection or fence portion of the bolt.  
  The key is accommodated by a roughly cylindrical lock-center or plug that rotates as the key is turned. The bottom of the plug terminates in an integral tongue-like cam. As the cam rotates, it engages a cam follower surface on a plate that in turn is integral with the lock bolt, withdrawing the bolt from the locked position as the fence slides into the accommodating opening provided by the aligned gates of the levers.  
  The basic problem of a lock-picker is to rotate each lever, without the benefit of a key, to a point at which each lever gate is in alignment with the fence portion of the bolt. This problem is readily solved by skilled lockpickers by any one of a number of methods, most of which employ some combination of the following steps. First, pressure or tension is exerted on the mov able locking members in a direction to open the lock. This step is typically accomplished by rotating the plug and its associated cam with some suitable tool. The tension thus applied takes up the clearances between the lever pivot pin and the pivot hole in the levers and between the fence and the top radius of the levers. Next, each individual lever is rotated with a picking tool. As the gate in each individual lever is aligned with the tool, the lever is moved further toward the fence by the amount of clearance between the pivot hole and the pivot pin under the urging force of an individual lever return Spring that conventionally biases each lever toward its home or locked position. Each lever gate is aligned with the fence in the manner described and each is held in that position by the combined force of the tensioned bolt and the lever return spring associated with each of the levers.  
  Various attempts have been made in the prior art to make locks of the type described more pick-resistant. These attempts include the use of baffle plates sandwiched between adjacent pairs of levers which makes picking access to the levers more difficult. Additionally, it is common practice to employ levers with one or more randomly spaced false gates a false gate being a relatively shallow notch adjacent to the true gate that tends to confuse the picker in his judgement as to the position of the true gate with respect to the fence. The skilled picker, however. is generally able to circumvent such so-called pick-resistant features with little or no difficulty. The above-identified Schweizer patent discloses still further design changes intended to inhibit fraudulent entry. For example, a common spring assembly is employed in lieu of individual lever springs, so that movement of any lever removes spring pressure from all of the other levers, thus increasing the chance for picking errors by overpicking.&#34; In addition to the top edge radius of each lever is formed with a different center of curvature, thereby largely destroying the pickers feel for the position of each lever.  
  Notwithstanding the foregoing improvements, attempts to pick locks of the type described are still occasionally successful, resulting in substantial revenue losses where the locks are used to protect coin telephone cash boxes. Accordingly, the broad object of the present invention is to increase the pick resistance of lever locks. An additional object is to prevent fraudulent entry by immobilizing the levers of the lock whenever the fence portion of the bolt can feel the gates formed in the levers.  
 SUMMARY OF THE INVENTION Each of the foregoing and additional objects are achieved in accordance with the principles of the present invention by a lever lock which includes means for preventing movement of the levers when the gates formed therein can be felt by the fence. More particularly, the lever lock includes a ratchet-like or multitoothed member spring biased towards a pointed tip formed on the top edge radius of each lever, so that. when engaged, the levers cannot be moved. In fully locked position, the lever lock is held away from the pointed lever tips by the engagement of an integral flange formed thereon with a portion of the bolt assembly. Normal key operation is as follows: First, the key is rotated and positions the levers so that the gates formed therein are aligned with the fence. Second, continued rotation of the key causes the cam to engage and partially retract the bolt, thereby allowing the lever lock to engage the pointed lever tips. Third, still further rotation of the key causes the bolt to disengage from the lever lock and move to its unlocked position.  
  By way of comparison, operation by a picker could proceed in two ways. If the levers are moved without rotating the cam, the fence cannot feel the gates formed therein. Alternatively, if the cam is rotated first, the bolt is partially retracted so that the fence can feel the gates, but the levers are held immobile by the lever lock and cannot be moved. Accordingly, the pick resistance of the lock is greatly enhanced.  
 BRIEF DESCRIPTION OF THE DRAWING The construction and operation of a lever lock in accordance with the instant invention will become more readily apparent to persons skilled in the art by reference to the following detailed description, when read in light of the accompanying drawing in which:  
  FIG. I is an exploded view of a lever lock constructed in accordance with the principles of the instant invention;  
  FIG. 2 is a plan view of a typical lever employed in a lock in accordance with the instant invention;  
  FIG. 3 is a plan view of the lock of FIG. 1 with certain parts removed, in the fully locked condition;  
  FIG. 4 is aplan view similar to FIG. 3 of the lock during one type of picking attempt;  
  FIG. 5 is a plan view similar to FIG. 3 of the lock during another type of picking attempt;  
  FIG. 6 is a plan view of the lock of FIG. I in a locked condition. with certain other parts removed;  
  FIG. 7 is a plan view similar to FIG. 6 of the lock in an unlocked condition: and  
  FIG. 8 is an exploded view. from the back. of a lever lock mechanism constructed in accordance with the invention.  
 DETAILED DESCRIPTION Construction and Assembly Referring now to FIG. I. there is shown an exploded view of a lever lock constructed in accordance with the principles of the instant invention. some of the parts of which are essentially similar to the lock shown in FIG. 1 of the above identified Schweizer patent. For ease of comparison. the same reference designations used in that patent are used herein to designate similar parts. The lock is housed in a metal case 10 which includes integral mounting flanges ll-I I. an integral top plate 12 and a lower plate (not shown). Mounting studs I3-I7 are affixed to the bottom of case 10, so that. when assembled, the top portion of each stud l3l7 is accommodated by a corresponding one of the mounting holes l8 IS in a protector plate 19 and by a corresponding one of the mounting holes 2020 in a lock cover 2]. Stud I4 also serves as a mounting for a bolt spring IOI, which aids in proper indexing of the fence on the bolt with the gates in the levers. Stud I5 also serves as a guide pin for lever lock 120. as will be described in more detail hereinafter.  
  Protector plate 19 includes an off-center aperture 33 which provides the upper bearing surfaces for a lock center or plug 23. Aperture 33 includes keying hole 35 to prevent pulling the plug 23 through plate 19, the hole 35 being located to the right of plug cam 36. counterclockwise rotation of the plug 23 is restricted by the engagement of the heel of bolt activating cam 37 with a portion of the bolt plate 38, so that the plug cannot be turned to keying hole 35.  
  Plug 23., which includes a main cylindrical portion 39, an integral cam 36 and an integral cylindrical nose 40, provides a deep enclosed keyway 41 and ensures separation from the bolt activating member or cam 37. The nose of plug 23 is accommodated by a hole 42 in the bolt activating cam 37. The nose 40 also protrudes into an aligned accommodating hole 22 in the bottom of case 10.  
  Each of the levers 2929 is mounted for pivotal movement on the pivot stud 17. Between each adjacent pair of levers 29-29 there is a baffle plate 43 secured against movement by studs 16 and I7. One of the baffle plates 4343 is mounted on top of the uppermost one of the levers 29. This baffle is formed so that a spring force is applied to the lever and baffle stack. when assembled, to provide better alignment between the key 24, and the levers. The baffle plates prevent interacting friction between adjacent levers 2929 and prevent straight-through picking access from an upper lever to a lower lever.  
  As shown in FIG. 2, a typical lever 29 used in a lock constructed in accordance with the present invention includes a main body portion 45 and a mechanical re turn arm portion 46. so that the lever is substantially L-shaped. An open slot or gate 47 formed in the curved edge portion 61 of the lever accommodates a fence leg 56 of the bolt assembly 44 when the lever is pivoted to its unlocked position by turning key 24. The lever cam also include one or more false gates 53. In addition. integral with and protruding past the curved edge portion (ml of each lever is a pointed tip 62 which is used in conjunction with the lever lock described hereinafter.  
  Referring now to FIG. 3, levers 29-29 are maintained in their normal or unextended positions by the action of two springs. The first is a generally U-shaped broad leaf spring I02 one leg of which bears against a sidewall of case 10 and the other leg of which includes an integral curved surface or lip 103 which bears against the right edge of the levers. when the levers are extended from their normal positions. The second is a broad leaf spring 104 connected at one end to a pin I05 affixed to the bottom of case I0. The other end of spring I04 is arranged to bear on the return arm portion 46 of levers 2929 under the urging of plug cam 36 when the latter is rotated to its normal position. thereby tending to pivot the levers to their unextended positions.  
  Bolt assembly 44. best shown in FIGS. 6 and 7. includes a bolt proper 54, which is accommodated by a strike aperture (not shown) to provide the basic locking connection. a fence 48 and a bolt 38. all integrally connected by brazing. welding or similar means. The fence 48 has a first leg 56 (which by itself may properly be identified as the fence) that is accommodated by the gates 47-47 of the levers 2929 when the levers are moved to the unlocked position. and a second leg or lug portion 57 which serves to limit picking access to the two edge portion of the levers. The bolt plate 38 is in sliding contact with the bottom of case 10 and its positioning is controlled in part by the slot 58 that accommodates the lever pivot stud I7. The bolt plate 38 has an open center portion with cam follower surfaces A, B. C and D that are engaged by the bolt activating cam 37 in a manner described hereinbelow under operation.&#34; The cam 37 has a generally circular aperture 42. which. as indicated above. accommodates the nose 40 of the plug 23, and a slot 72 which accommodates the key 24. The cam 37 also includes a generally rectangular aperture I06 which communicates with aperture 42 and is adaptedd to receive a generally rectangular nub (not shown) which extends from the nose 40 of the plug. The purpose of aperture 106 and the engaged nub is to maintain key slot 72 of cam 37 in alignment with key slot 4] of plug 23 of cam 37 irrespective of the angular position of the latter.  
  As shown in FIG. I. a lock constructed in accordance with the principles of the instant invention includes a lever lock mechanism designated generally at I20. The mechanism includes a main body portion having an integral multitoothed surface 122. a channel or groove I23 formed therein in a direction essentially perpendicular to surface 122, and a pair of integral pins I24, on the top surfaces thereof on either side of groove 123. The lever lock I20 is positioned within case I0 so that stud 15 is accommodated in groove I23. permitting only vertical sliding movement. Horizontal movement is also prohibited by dimensioning the lever lock so that the right side 126 thereof is in sliding contact with the right interior sidewall of case 10 while the left edge I27 thereof is in sliding contact with the side of fence 56. The rear face of lever lock I20 is in sliding contact with the bottom of case I0.  
  A pair of coiled springs 128. I29 are positioned around pins I24 and I25, respectively. and extend between the top surface of lever lock I20 and the interior surface of top plate 12. These springs tend to urge the lever lock mechanism 120 in a downward direction so that multitoothed surface 122 is moved into engagement with pointed tips 62-62 of levers 29-29. However. in certain circumstances described hereinafter, engagement does not occur because downward movement of lever lock 120 is prevented by the engagement of integral flange I formed on the back surface thereof (see FIG. 8) with corner E of bolt plate 38 of bolt assembly 44 when the latter is in its extended (locked) position.  
 Operation Assume that the lock is in the locked position and that the key 24 has been inserted in the plug slot. as shown in FIG. 3. As the key 24 is turned to the right (clockwise). each of the key notches 64 engages a corresponding one of the levers 29-29 on its left edge. causing it to pivot around stud 17 against the biasing force of spring 102. Continued turning of the key after gates 47-47 have been aligned with the fence leg 56. forces the cam 37 to rotate clear of the cam locking surface A (FIG. 6) until it impinges against the cam follower driving surface C, which begins to drive the bolt assembly 44 and thus the bolt 54 inwardly toward its unlocked position. As bolt assembly 44 moves down. so too does lever lock 120 under the urging of springs 128 and 129. until multitoothed surface 122 is in full engagement with pointed lever tips 62-62. As the key is rotated still further. corner E of bolt plate 38 separates from flange 130 of lever lock 120. and the bolt 54 is withdrawn to its fully unlocked position. The final portion of travel of cam 37 brings it into contact with the cam follower locking surface D. as shown in FIG. 7.  
  ln locking the lock. key 24 is rotated counterclockwise so that cam 37 clears the cam follower surface D of bolt plate 38 and bears against the cam follower driving surface B which drives the bolt assembly 44 and thus bolt 54 outwardly toward its locked position. During the travel of bolt plate 38. corner E again engages flange I30 of lever lock 120 and carries the same upward so that pointed lever tips 62-62 are no longer held immobile by multitoothed surface l22. At the end of its travel. the cam 37 comes to rest against cam follower locking surface A. At the same time. the combined action of spring 102 and the plug cam 36 bearing against spring &#34;)4 which in turn exerts a pivotal force on the return arm portions 46-46 of levers 29-29 causes each lever to be driven back to its unextended (locked) position.  
  In contrast to the normal key operation described above. fraudulent entry by a picker can be attempted in one of two ways. First. the picker. who desires to feel the gates formed in the levers 29-29 can rotate the plug 23 (and thus cam 37) with a suitable tool so that fence leg 56 is drawn into contact with the curved edge portions 6l-6l of the levers. In so doing. however, bolt plate 38 begins its descent, as does lever lock 120. so that when the gates can be felt by the fence. the levers are held stationary by the engagement of lever tips 62-62 with multitoothed surface 122, as shown in FIG. 4. Accordingly, the picker is helpless since he cannot then move the levers in his attempt to align the gates formed therein with fence 56. As a second procedure. the picker could move some or all of the levers with a picking tool before rotating plug 23. However. he cannot then feel the gates formed in the curved edge portions 61-61 thereof. and the distance each lever is moved could amount to no more than a guess. Of course when the plug is subsequently rotated. as shown in FIG. 5. the levers 29-29 are again held in a fixed position. and corrections of misalignments cannot thereafter be made.  
  As can be seen from the foregoing description of a lock constructed in accordance with the principles of the instant invention. fraudulent entry techniques are defeated by the provision of a lever lock mechanism which makes it impossible to move the levers at times when the gates formed therein can be felt by the fence portion of the bolt assembly. When a legitimate key is used. the levers are initially positioned so as to align the gates formed therein with the fence. before the levers are immobilized by further key rotation which drives the bolt assembly toward its unlocked position. thereby actuating the lever lock. Hence. normal operation is not impeded.  
  It is to be understood that the embodiment described herein is merely illustrative of the principles of the invention. Various modifications thereto may be affected by persons skilled in the art without departing from the spirit and scope of the invention.  
 What is claimed is:  
 l. A key operated lock including a bolt including a fence portion.  
 a plurality of moveable levers each having a curved edge portion and a gate formed therein for accommodating said fence portion when said levers are properly positioned. so as to allow said bolt to assume its unlocked position.  
 a cam arranged to move said fence portion of said bolt from its locked position toward said curved edge portion of said levers and into said gate when properly positioned. and  
 means for preventing movement of said levers when said fence portion of said bolt is moved toward contact with said curved edge portion of said levers by activation of said cam.  
 wherein said levers each include a pointed tip protruding from said curved edge portion.  
 said movement preventing means includes a multitoothed surface adapted to engage said pointed tip.  
 said lock further includes at least one spring member adapted to bias said movement preventing means including said multitoothed surface toward said pointed tip. and  
 said movement preventing means further includes a flange portion adapted for engagement with a portion of said bolt when said bolt is in its fully locked position so as to maintain said multitoothed surface in spaced relation from said pointed tip. and adapted for disengagement from said portion of said bolt when said bolt is in its fully unlocked position.  
 2. A key operated lock comprising a bolt assembly including a fence portion and a strike engageable tongue portion.  
 at least one pivotally moveable lever including a pointed tip portion and a curved edge portion having a slot formed therein for accommodating said fence portion when said lever is pivoted into correct position by initial rotation of a key.  
 means responsive to further rotation of said key for moving said bolt assembly including said fence portion from its locked position in which said tongue portion engages said strike toward its unlocked po- 7 sition in which said tongue portion is disengaged from said strike and said fence portion enters said slot formed in said curved edge portion of said lever. and  
 means responsive to movement of said bolt assembly from its locked position toward its unlocked position for preventing pivotal movement of said levers.  
 wherein said movement responsive means includes a when said bolt is in its unlocked position.