Locking mechanism for expandable rooms

A locking mechanism for joining together first and second members that are moveable relative to each other from an unlocked position to a locked position in which the members are aligned and locked together, said locking mechanism comprising:

• a receiver adapted to be secured to the first member;
• the receiver having a wall that defines a receiving chamber with an open end;
• the wall having a first locking element within the receiving chamber;
• an actuating mechanism housing adapted to be secured to the second member and having an open end positioned to face the open end of the receiver housing when the first and second members are in a relative position to be locked together;
• the actuating mechanism housing having a second locking element near the open end of the housing;
• the actuating mechanism housing having a cylinder containing a barrel that defines a first chamber with a longitudinal axis;
• a first piston moveable forwardly and rearwardly in the first chamber along the longitudinal axis;
• a second piston axially moveable in the first chamber and spaced from the first piston to define a second chamber between the first piston and the second piston;
• the first piston having an annular wall extending forwardly to define a third chamber within the first piston;
• a mandrel having a rear end and a forward end received in the third chamber, said mandrel being moveable forwardly and rearwardly within the third chamber relative to the first piston;
• a connecting rod extending through the first piston and interconnecting the second piston and the rear end of the mandrel;
• the mandrel being comprised of a main body that is larger at the rear end of the mandrel than at the forward end;
• a locking member positioned on the main body of the mandrel and moveable axially relative to the main body;
• the locking member being normally positioned near the forward end of the main body and having a first locking element at the forward end of the locking member and a second locking element at the rear end of the locking member;
• the distance between the first and second locking elements of the locking member being the same as the distance between the first locking element in the receiver and the second locking element in the actuating mechanism housing when the receiver and housing are locked together;
• and means providing fluid under pressure into the first and second chambers for moving the first and second pistons to advance the forward end of the main body into the receiver and align the first and second locking elements of the locking member with the locking elements in the actuating mechanism housing and in the receiver and to force the locking elements together.