Combined spring and shock absorber units for vehicles; hydraulic rotary shock absorbers for vehicles; rotary shock absorbers for vehicles; shock absorber adjustment apparatus for vehicles; shock absorbers being parts of vehicle suspension; shock absorbers for automobiles; shock absorbers for the suspension units of vehicles; shock absorbers for vehicle suspension; shock absorbers for vehicles; shock absorbing cylinders (parts of vehicles); shock absorbing springs for vehicles; suspension shock absorbers for vehicles; vehicle shock absorbers