Method of resin sealing an object with apparatus including a gas spring

A gas spring using a gas as a buffer medium, comprising:

• (a) a housing defining a plurality of cylinders respectively having first ends and second ends, said cylinders being arranged in parallel;
• (b) a plurality of pistons slidably fitted in said plurality of cylinders respectively for defining spaces therewith and with said cylinders including said second ends which are hermetically sealed relative to an outside of said housing and communicate with each other;
• (c) means for limiting a sliding range of each of said plurality of pistons to prevent each of said pistons from projecting out over a predetermined degree from said housing,
• wherein said means for limiting a sliding range of said pistons comprises an end wall of said housing at said first ends of said cylinders, and
• (d) cartridges airtightly fixed in said cylinders respectively,
• wherein each of said pistons is provided with a piston rod and a rod retainer, said piston rods each slidably and airtightly penetrating a corresponding one of said cartridges,
• wherein each retainer is fixedly mounted on a bottom of a corresponding piston rod and slidably contacts an inner surface of a corresponding one of said cylinders,
• wherein each retainer defining a corresponding vent, and
• wherein each of said spaces is defined with a corresponding retainer, a corresponding piston rod, a corresponding cylinder inner surface, and a corresponding one of said second ends.