Shock absorber piston rod

Shock absorber piston rod

All hydraulic shock absorbers works by the principle of converting kinetic energy (movement) into thermic energy (heat). So as to fluid in the shock absorber is forced to flow through restricted outlets and valve systems, thus generating hydraulic resistance.
Telescopic shock absorber (damper) so called bump stroke and rebound stroke,and it can be compressed and extended .Telescopic shock absorbers can be subdivided in:

1. Bi-tube, or twin-tube dampers, available in hydraulic and gas-hydraulic configuration.
2. Mono-tube dampers, also called high pressure gas shocks.

Working principle of a bi-tube shock absorber work?

Bump stroke

When the piston rod is pushed in, oil flows without resistance from below the piston through the orifices and the non-return valve to the enlarged volume above the piston. At the same time, a quantity of oil is displaced by the volume of the rod entering the cylinder. This volume of oil is forced to flow through the bottom valve into the reservoir tube (filled with air (1 bar) or nitrogen gas (4-8 bar). The resistance, encountered by the oil on passing through the footvalve, generates the bump damping.

Rebound stroke

When the piston rod is pulled out, the oil above the piston is pressurized and forced to flow through the piston. The resistance, encountered by the oil on passing through the piston, generates the rebound damping. Simultaneously, some oil flows back, without resistance, from the reservoir tube (6) through the footvalve to the lower part of the cylinder to compensate for the volume of the piston rod emerging from the cylinder.