Adjustable foundation

An adjustable mattress assembly dimensioned to support a mattress configured to accommodate two prone users, comprising:

• a foundation frame comprising side frame members and transverse frame members attached at respective ends of the side frame members to define a generally rectangular shape, and at least one cross rail extending between the side frame members;
• a mattress support surface configured to support a mattress dimensioned to accommodate two prone users, the mattress support surface including a head and back section hingedly connected to an intermediate seat section at one end and a leg and foot section hingedly connected to the intermediate seat section at another end, wherein the intermediate seat section includes a first portion and a second portion, wherein the first portion is hingedly connected to the head and back section and the second portion is hingedly connected to the leg and foot section;
• and
• a first actuator having an extending and retracting member operatively coupled to a linkage assembly to effect inclination or declination of the head and back section relative to the intermediate seat section and inclination or declination of the foot and leg section relative to the intermediate seat section, wherein the linkage assembly comprises a linkage support frame configured to be seated on the foundation frame;
• first and second spaced apart torsional members coupled to the linkage support frame underlying each end of the intermediate seat section;
• a cross bar coupled to the linkage support frame and underlying a selected one of the first and second torsional members, and link arms having an end pivotally connected to crank arms coupled to the first and/or second torsional members, wherein the first actuator has one end coupled to the cross rail and another end coupled to one of the crank arms effective to rotate the torsional member upon extension and retraction of the first actuator and effect inclination or declination of the head and back section and the leg and foot section, wherein the first actuator is further operative to effect an increase or decrease in a length of the intermediate seat section by movement of the first portion relative to the second portion upon inclination or declination of the head and back section and the foot and leg section;
• and
• wherein the head and back section further comprises movable rectangular shaped lumbar support members disposed within complementary shaped openings in the head and back section, wherein each of the lumbar support members is positioned to provide adjustable lumbar support for a selected one of the users, and wherein each of the lumbar support members is hingedly connected at a top end and independently operative with a lumbar member actuator coupled thereto to pivot upwardly relative to a plane defined by the head and foot section.