Mechanical override of an electronic lock

1. An electromechanical lock comprising:

a lock extension and a blocking module, the blocking module having an interior region;

a pivot bolt mounted in the interior region for rotation about a rotation axis between a nominal position and an unsecured position, wherein the pivot bolt is biased to its nominal position by a first torsion spring;

a first blocker disposed in the interior region for movement between a nominal position and an unblocking position, wherein the first blocker is biased to its nominal position by a compression spring;

a second blocker disposed in the interior region for movement between a nominal position and an unblocking position, wherein the second blocker is biased to its nominal position by a second torsion spring; and

an override disposed in the interior region for movement between a nominal position and an override position, the lock being in a secured condition when the first and second blockers and the override are in their respective nominal positions and an unsecured condition when the second blocker is in its unblocking position.

2. The lock of claim 1 , wherein the override includes a plunger configured to engage the second blocker to move the second blocker out of its nominal position when the override moves to its override position.

3. The lock of claim 1 , wherein the override includes a drive mechanism configured to translate the rotation of a key in a lock cylinder into movement of the override from the nominal position to the override position.

4. The lock of claim 3 , wherein a plunger includes a pin-receiving slot and a drive train includes a gear having a pin formed thereon and disposed in the pin-receiving slot, whereby rotation of the gear moves the pin to urge the plunger to the override position.

5. The lock of claim 1 , wherein the second blocker is in the unblocking position and the lock is unsecured when the override is in the override position.

6. The lock of claim 1 , wherein the first blocker moves linearly between its nominal and unblocking positions and the second blocker rotates between its nominal and unblocking positions.

7. The lock of claim 1 , further comprising a motor configured for moving the second blocker.

8. An electromechanical lock comprising:

a lock extension and a blocking module, the blocking module having an interior region;

a pivot bolt mounted in the interior region for rotation about a rotation axis between a nominal position and an unsecured position, wherein the pivot bolt is biased to its nominal position by a first torsion spring;

a first blocker disposed in the interior region for linear movement between a nominal position and an unblocking position, wherein the first blocker is biased to its nominal position by a compression spring;

a second blocker disposed in the interior region for rotational movement from a nominal position blocking the first blocker to an unblocking position, wherein the second blocker is biased to its nominal position by a second torsion spring; and

an override disposed in the interior region for movement between a nominal position and an override position, the lock being in an unsecured condition when the override is in the override position.

9. The lock of claim 8 , wherein the second blocker is in the unblocking position when the override is in the override position.

10. The lock of claim 8 , wherein the override includes a plunger having a pin-receiving slot and a drive mechanism having at least one gear, the plunger being movable between a nominal position and an override position, the at least one gear including a pin disposed in the pin-receiving slot, the plunger moving to the override position in response to rotation of the at least one gear.

11. The lock of claim 8 , wherein the override includes a drive gear, an idler gear and a drive pin gear, the drive pin gear being configured to convert rotation of the drive gear into movement of the override between the nominal position and the override position.

12. The lock of claim 8 , further comprising a motor configured to rotate the second blocker from its nominal position.

13. The lock of claim 8 , wherein the first blocker blocks rotation of the pivot bolt in its nominal position and allows rotation of the pivot bolt to its unsecured position.

14. An electromechanical lock having a secured condition and an unsecured condition comprising:

a lock extension and a blocking module, the blocking module having an interior region;

a pivot bolt mounted in the interior region for rotation about a rotation axis between a nominal position and an unsecured position, wherein the pivot bolt is biased to its nominal position by a first torsion spring;

a first blocker disposed in the interior region for movement between a nominal position and an unblocking position, wherein the first blocker is biased to its nominal position by a compression spring;

a second blocker disposed in the interior region for movement between a nominal position and an unblocking position, the pivot bolt being prevented from moving to the unsecured position when the second blocker is in its nominal position, wherein the second blocker is biased to its nominal position by a second torsion spring; and

a manual override disposed in the interior region positioned to drive a plunger, wherein the plunger translates linearly between a nominal position and an override position.

15. The lock of claim 14 , wherein the lock is in a secured condition when the first and second blockers are in their respective nominal positions and unsecured when the first and second blockers are in their respective unblocking positions.

16. The lock of claim 14 , wherein the plunger is positioned to move the second blocker to its unblocking position.

17. An electromechanical lock comprising:

a lock extension and a blocking module, the blocking module having an interior region;

a pivot bolt mounted in the interior region for rotation about a rotation axis between a nominal position and an unsecured position, wherein the pivot bolt is biased to its nominal position by a first torsion spring;

a first blocker disposed in the interior region for movement between a nominal position in which the pivot bolt is prevented from moving out of its nominal position and an unblocking position in which the pivot bolt is permitted to move from its nominal position, wherein the first blocker is biased to its nominal position by a compression spring;

a second blocker disposed in the interior region for movement between a nominal position in which the pivot bolt is prevented from moving out of its nominal position and an unblocking position in which the pivot bolt is permitted to move from its nominal position, wherein the second blocker is biased to its nominal position by a second torsion spring; and

an override movable between a nominal position and an override position, the override being configured to allow the pivot bolt to move from its nominal position when the override is in the override position.

18. The lock of claim 17 , wherein the second blocker moves to its unblocking position in response to movement of the override to the override position.

19. The lock of claim 17 , wherein the override includes a plunger and a drive mechanism, the plunger moving linearly between a nominal position and an override position in response to movement of the drive mechanism.