A locking assembly attachable to a manhole cover includes an arm disposable in a lowered position with the arm disposed in a first orientation engageable with a manhole frame supporting the manhole cover to inhibit removal of the manhole cover from a manhole frame, and disposable in a raised position and in a second orientation operable to allow removal of the manhole cover from the manhole frame. In an embodiment, the locking assembly may include the arm attached to a movable member having a spiral, helix, or curved groove and in which the movable arm is receivable in a bushing and a pin receivable in the groove.

The present invention relates to a secure barrier for an underground valve box. The device may have a bolt and a nut for adjusting the length of the bolt to position curved plates to press against the inner circumference of a cylindrical valve box. The bolt housing may include a flange that protrudes through a slot in a horizontal metal plate. The plate may have handles for ease of lifting and replacement of the plate. The protruding flange may feature a hole for insertion of a padlock. When the padlock is secured, the plate cannot be removed from the cylindrical valve box as the adjustable bolt housing cannot move sufficiently to retract the curved plates from the inner cylindrical surface of the valve box. Thus, only authorized personnel with the proper padlock key or combination can operate the valve, deterring vandals.

A device for preventing unauthorized opening of a door comprises a bracket, a main handle, and a wedge. The bracket is adapted for mounting the device to a door. The main handle is pivotably attached to the bracket. The main handle has a pivot end attached to the bracket and an opposing grasping end. The main handle is selectively pivotably movable upward and downward. The main handle is adapted such that pivoting the main handle upward moves the grasping end toward the door and pivoting the main handle downward moves the grasping end away from the door. The wedge is pivotably affixed to the main handle and biased toward the door when the main handle is in a downward position. The main handle is adapted to push a distal end of the wedge at least partly under a bottom surface of the door when the main handle is pivoted downward.

A locking assembly attachable to a manhole cover includes an arm disposable in a lowered position with the arm disposed in a first orientation engageable with a manhole frame supporting the manhole cover to inhibit removal of the manhole cover from a manhole frame, and disposable in a raised position and in a second orientation operable to allow removal of the manhole cover from the manhole frame. In an embodiment, the locking assembly may include the arm attached to a movable member having a spiral, helix, or curved groove and in which the movable arm is receivable in a bushing and a pin receivable in the groove.

A controllable front door opening structure for a double-door display case includes a case body, where a front side of the case body is rotatably connected to a front door; an inner side of the front door is connected to a limiting member; the limiting member rotates synchronously with the front door; a locking member is provided in the case body; the locking member limits rotation of the limiting member; and the locking member translates or rotates to unlock the limiting member. By controlling the locking member at a rear door of the case body to move forward and backward or to rotate, the front door is locked or unlocked.