Automatic blocking device for limiting a sliding movement of a first structure mounted adjacent to a second structure

An apparatus comprising:

• a fixed frame member;
• a movable frame member mounted for linear movement relative to the fixed frame member in a first direction and a second direction, the movable frame member having a slide surface and a stop surface,
• a lockout device for selectively blocking the linear movement of the movable frame member in the second direction, the lockout device comprising:
• a lock tab pivotably mounted to the fixed frame member at a location adjacent to the movable frame member, the lock tab having a first end, a contact surface at the first end, a second end, a first cam surface and a second cam surface, and
• a body projecting from the movable frame member and configured to move along a path as the movable frame member moves relative to the fixed frame member,
• wherein the lock tab has a first orientation in which the first end contacts the slide surface and the second end is outside the path and a second orientation in which the first end contacts the stop surface and the second end is outside the path and a third orientation in which the first end is spaced from the movable frame member and the second end is in the path, and
• wherein the lock tab is configured such that moving the movable frame member in the first direction from a first position to a second position causes the lock tab to move from the first orientation to the second orientation and moving the movable frame member from a third position to a fourth position causes the body to contact the first cam surface and shift the lock tab from the second orientation to the third orientation, and moving the movable frame member from the third position to the first position causes the body to contact the second cam surface and shift the lock tab from the third orientation to the first orientation.

A lockout device for selectively blocking linear movement of a movable frame member relative to a fixed frame member, the lockout device comprising:

• a lock tab pivotably mountable to the fixed frame member adjacent to the movable frame member and having a contact surface configured to slidably engage a slide surface of the movable frame member when the lock tab has a first orientation, the movable frame member including a stop surface at one end of the slide surface;
• holding means for releasably holding the lock tab in a second orientation with the contact surface spaced from the slide surface;
• and
• a body mountable to the movable frame member and configured such that movement of the movable frame member in a first direction relative to the fixed frame member causes the body to contact a first portion of the lock tab and push the lock tab into the second orientation and movement of the movable member in a second direction relative to the fixed frame member causes the body to contact a second portion of the lock tab and pivot the lock tab into the first orientation,
• wherein the lock tab is movable independently of the holding means, and
• wherein the lock tab is shiftable to a third orientation in which the contact surface engages the stop surface.