A shock absorber is not just a spring. lts function is not simply to compress(inflate),but to control rebound. lf there ware only a spring, your car would bounce around non-stop like a ball. the job of the shock absorber (the oil/gas cylinder) is to restrain the spring's bouncing, allowing the rear wheels to maintain contact with the road surface for as long as possible. (There are 4 more spare parts files.)
SLDPRT (SolidWorks, filesize: 2.18 MB)