A structure providing a patient support surface is transferable between a stationery support column and a wheeled transport carriage with the transport carriage, the support column and the support surface providing structure having connecting parts which cooperate to securely hold the structure to the transfer carriage or to the support column when the structure is mounted on the transfer carriage or the support column, the connecting parts during transfer of the structure from the transfer carriage to a support column, or vice versa, being automatically moved between latched and unlatched conditions to allow the transfer to occur and having security features preventing the patient support surface providing structure from being inadvertently unfastened from both the support column and the transport carriage during a transfer procedure.