Theft-resistant fastener system

• US 4,938,108 A
• Filed: 02/06/1989
• Issued: 07/03/1990
• Est. Priority Date: 01/23/1983
• Status: Expired due to Fees

• Current Assignee: Abraham Levy
• Original Assignee: Abraham Levy
• Inventors: Mekler, Dan
• Primary Examiner(s): MEISLIN, DEBRA S
• Application Number:
  US07/307,314
• Time in Patent Office: 512 Days
• Field of Search: 81/436, 81/442-444, 81/448-449, 81/460-461, 81/176.1-176.3, 411/402-403, 411/405, 411/410, 411/407, 411/408, 411/427, 411/910, 411/371-373, 411/396-397, 279/22, 279/75, 285/277, 285/314-316, 285/84, 285/86, 403/325, 403/DIG. 6
• US Class Current: 81/176.15
• CPC Class Codes: B25B 13/20 Arrangements for locking the jaws
• CPC Class Codes: B25B 13/485 for theft-proof screws, bolts or nuts
• CPC Class Codes: B25B 13/50 for operating on work of special profile, e.g. pipes
• CPC Class Codes: F16B 23/0061 with grooves, notches or splines on the external peripheral surface designed for tools engaging in radial direction F16B23/003 takes precedence
• CPC Class Codes: F16B 41/005 Measures against unauthorised operation of bolts, nuts or pins F16B23/0007, F16B23/0061, F16B23/0069, F16B23/0076 and F16B31/02 take precedence; locks, keys E05B; for valves, taps or cocks F16K35/00; for pipe-joints with swivel-nuts F16L19/005
• CPC Class Codes: Y10S 411/91 Antitamper means

Abstract

A theft-resistant fastener system includes a rotatable wrench adapted to engage a head portion of a fastener and to rotate that fastener and head portion about a fastener axis. The wrench and fastener jointly have at least three ball-and-socket joints distributed about the fastener axis. Each of these ball-and-socket joints has a ball in the wrench and a socket in the head portion of the fastener, with each socket being provided with a circular cross-section about a socket axis extending at an acute angle to the fastener axis. The wrench has a releasable actuator for pressing the balls into the sockets preparatory to and during rotation of the wrench about the fastener axis. The head portion of the fastener is prevented from clearing the balls, when the actuator presses these balls into the sockets, by providing that head portion at each socket with an overhang extending over part of the ball in that socket. A need for means for biasing the balls out of the sockets upon release of the actuator is avoided by providing each overhang with an outer limit closer to the fastener axis than a center of a corresponding one of the balls of the ball-and-socket joints. Actuation of the fastener by a conventional wrench is prevented by providing the head portion with outward slopes at the sockets and otherwise about the fastener axis.

Claims

1. A theft-resistant fastener system including a rotatable wrench adapted to engage a head portion of a fastener and to rotate said fastener and head portion about a fastener axis, said fastener system made by the method comprising in combination the steps of:

providing said wrench and fastener jointly with at least three ball-and-socket joints distributed about said axis, including providing each of said ball-and-socket joints with a ball in said wrench and a socket in said head portion of the fastener, each socket being provided with a circular cross-section about a socket axis extending at an acute angle to said fastener axis;

providing said wrench with a releasable actuator for pressing said balls into said sockets preparatory to and during rotation of said wrench about said fastener axis;

preventing said head portion from clearing, said balls, when said actuator presses said balls into said sockets, by providing said head portion at each socket with an overhang extending over part of the ball in that socket;

avoiding a need for means for biasing the balls out of the sockets upon release of said actuator by providing each overhang with an outer limit closer to said fastener axis than a center of a corresponding one of the balls of said ball-and-socket joints; and

preventing actuation of said fastener by a conventional wrench by providing said head portion with a sloped outer surface at the sockets about said fastener axis.

2. A system as claimed in claim 1, wherein:

said acute angle substantially is 60°

relative to said fastener axis.

3. A system as claimed in claim 1, wherein said method includes the step of:

restricting removal of said fastener to a specifically authorized wrench by distributing said ball-and-socket joints irregularly about said fastener axis.

4. A system as claimed in claim 1, wherein said method includes the step of:

restricting removal of said fastener to a specifically authorized wrench by varying said sockets in size about said fastener axis.

5. A system as claimed in claim 4, wherein said method includes the step of:

further restricting removal of said fastener to a specifically authorized wrench by distributing said ball-and-socket joints irregularly about said fastener axis.

6. A system as claimed in claim 5, wherein said method includes the step of:

further restricting removal of said fastener to a specifically authorized wrench by arranging said sockets in different planes extending perpendicularly to said fastener axis.

7. A system as claimed in claim 1, wherein said method includes the step of:

restricting removal of said fastener to a specifically authorized wrench by arranging said sockets in different planes extending perpendicularly to said fastener axis.

8. A system as claimed in claim 7, wherein said method includes the step of:

further restricting removal of said fastener to a specifically authorized wrench by distributing said ball-and-socket joints irregularly about said fastener axis.

9. A system as claimed in claim 7, wherein said method includes the step of:

further restricting removal of said fastener to a specifically authorized wrench by varying said sockets in size about said fastener axis.

10. A theft-resistant fastener system comprising in combination:

a fastener with a head portion having a sloped outer surface about a fastener axis;

a rotatable wrench adapted to engage a head portion of said fastener and to rotate said fastener and head portion about said fastener axis;

said wrench and fastener jointly comprising at least three ball-and-socket joints distributed about said axis, each of said ball-and-socket joints having a non resiliently biased ball in said wrench and a socket in said sloped outer surface of said head portion of the fastener so as to prevent actuation of said fastener by a conventional wrench, each socket having a circular cross-section about a socket axis extending at an acute angle to said fastener axis;

said wrench including a releasable actuator means for pressing said balls into said sockets preparatory to and during rotation of said wrench about said fastener axis; and

said fastener including means for preventing said head portion from clearing said balls, when said wrench presses said balls into said sockets, including in said head portion, at each socket, an overhang extending over part of the ball in that socket, each overhang having an outer limit closer to said fastener axis than a center of a corresponding one of the balls of said ball-and-socket joints.

11. A theft-resistant fastener system as claimed in claim 10, wherein:

said acute angle substantially is 60°

relative to said fastener axis.

12. A theft-resistant fastener system as claimed in claim 10, wherein:

said ball-and-socket joints have an irregular distribution about said fastener axis.

13. A theft-resistant fastener system as claimed in claim 10;

wherein;

said ball-and--socket joints are of varying size about said fastener axis.

14. A theft-resistant fastener system as claimed in claim 10;

wherein;

said ball-and-socket joints are in different planes extending perpendicularly to said fastener axis.

15. A theft-resistant fastener system as claimed in claim 10, wherein:

each ball is disposed in a ball retaining socket having a circular cross-section about a ball retaining socket axis extending at an acute angle to said fastener axis.

16. A theft-resistant fastener system as claimed in claim 10, wherein:

each ball is disposed in a ball retaining socket having a circular cross-section about a ball retaining socket axis extending at an acute angle of substantially 60°

relative to said fastener axis.