Pneumatic mat with safety apparatus

A pneumatic bed, comprising

• an inflatable member,
• a fixed member,
• a valve,
• an element having a port in which said valve is seated, said element normally confining inflation gas supplied to said inflatable member, said element normally being movable with respect to said fixed member upon inflation of said inflatable member, and
• flexible member means extending between said fixed member and said valve, for unseating said valve when said element is moved beyond a predetermined point with respect to said fixed member when said inflatable member is inflated beyond a pre-determined limit, wherein
• said inflatable member is constituted by one of a plurality of inflatable mats affixed to said bed,
• said element is a plate mounted on top of said inflatable mat,
• said valve is situated within said inflatable mat,
• said flexible member means are constituted by one of a rope, wire, cord, or spring interconnecting said valve and said fixed member such that when said mat is inflated beyond said predetermined limit, said flexible member means are tensioned and unseat said valve from said port,
• and additionally comprising
• a shaft fitted against said valve and connected to said flexible member means, said shaft mounted for free sliding with respect to said element,
• spring means for biasing said valve upwardly to seat in said port, said spring means extending about said shaft, and
• a frame affixed to said plate from underneath and having a hole through which said shaft slides, said spring means being mounted upon said frame which is situated within said inflatable mat,
• wherein said valve is disposed to reseat in said port when said inflatable mat deflates below said predetermined limit.