Mechanical extension apparatus for extendable seat and extendable seat

An extendable seat, comprising:

• a base;
• a seat disposed on the base;
• a backrest disposed on a back side of the seat;
• a footrest disposed on a front side of the seat;
• and
• a mechanical extension apparatus, comprising:
• a reclining apparatus comprising multiple links attached to the seat, the backrest and the footrest of the extendable seat, wherein the reclining apparatus is configured to convert the extendable seat between two positions, a sitting position and a lying position, and wherein, in the sitting position, the backrest is substantially upright and the footrest is folded below the seat;
• and in the lying position, the backrest is reclined and the footrest is substantially horizontally disposed in front of the seat;
• an actuator that is attached to the reclining apparatus, wherein the actuator is configured to electronically convert the extendable seat between the sitting position and the lying position, and wherein, in response to converting from the sitting position to the lying position, the footrest extends forward to the front of the seat and the backrest is configured to recline;
• and
• a swing limit, wherein the swing limit is configured to allow the extendable seat to glide or rock back and forth in the sitting position, and to prevent the extendable seat from gliding or rocking in the lying position,
• wherein the multiple links comprise a front swing rod and a rear swing rod, and the swing limit comprises:
• a first limit member, a second limit member, and a chute limit member, a rear end of the first limit member being pivotally connected to a front end of the second limit member, and the chute limit member comprising a swing limit chute,
• wherein a first limit bush is provided on a front end of the first limit member, a second limit bush is provided on a rear end of the second limit member, and the second limit bush is movably fitted in the swing limit chute,
• wherein the first limit bush and the second limit bush are configured to respectively abut on an inner side of the front swing rod and an inner side of the rear swing rod to prevent the extendable seat from gliding or rocking in the lying position.