A transport cart for attaching to a patient care apparatus having a locking system that converts the forward caster of the transport cart from an omni-directional pivotable caster to a fixed directional device by restraining its pivoting about a vertical axis. The forward caster is located at about the center of the footprint of the combined transport cart/patient care apparatus and the fixed directional movement of the forward caster provides stability in moving the combined apparatus. The locking mechanism may be internal to the caster or may have a pair of pivotable lock arms that contact the patient care apparatus as the two are brought together and the pivotable lock arms pivot to a locked position where they sandwich the caster therebetween to restrain its ability to pivot. The locking mechanism automatically or manually releases the forward caster to again freely pivot when the transport cart/patient care apparatus are separated.