Gas-filled suspension system is being one of the vital equipment in any vehicle responsible for stability and control. When we see the rear shock absorbers of any compared, they are majorly categorized into two- Mono Shock and Dual Shock absorbers. In either of the two now a days “Gas Charged or Nitrox” dampers are commonly seen. You must be wondering what these dampers are and how good they are the piston. to the regular two-wheelers shock absorbers? Well, we will try to explain what these Gas Filled Dampers .The gas filled shock-ups can be easily differentiated by ‘Canister’ attached to the conventional spring-loaded shock absorber. It is this Canister which holds the gas inside, it is mostly Nitrogen gas used in these cans and that is the reason why it is also known as ‘Nitrox’ dampers. Before we go ahead with the details of the topic it is mandatory to check how a shock absorber (conventional) works. The job of the spring is to bounce back from the uneven surface rather than soaking the impact, it is the Piston along with the Oil responsible for the damping action. So, when the vehicle hits a bump, the piston inside the damper moves within the tube filled with damping oil along with perforated Valves.
All hydraulic shock absorbers work by the principle of converting kinetic energy (movement) into thermic energy (heat). For that purpose, fluid in the shock absorber is forced to flow through restricted outlets. A telescopic shock absorber (damper) can be compressed and extended; the so-called bump stroke and rebound stroke. Telescopic shock absorbers can be subdivided The oil is then dissipated from the holes of the valve and hence allowed limited resistance to the movement of piston thereby performing efficient damping. This up and down movement of the piston inside the oil oil-filled tube caused a phenomenon called ‘Cavitation’ in the damping oil- in simple words; it is foaming of the oil. What happens when there is excessive movement takes place, the gas molecules present in the oil (which is about 10%) start releasing due to loosening of the bond between the oil molecules and the gas molecule present in the damping oil, resulting from the formation of air bubbles which eventually takes the form of Foam.
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 foot valve to the lower part of the cylinder to compensate for the volume of the piston rod emerging from the cylinder.
Gas-filled dampers are used to prevent foaming of the damping oil valve, so that the efficiency of the shock absorber remains constant throughout. The canister is used to be filled with pressurized Nitrogen gas, which further act as reservoir for both oil and Nitrogen gas. The role of the Nitrogen gas is to keep the damping oil pressurized so that the gas molecules present in the oil remain bonded with the oil molecules and must not get loosen to form bubbles/foam and hence prevent the Cavitation. Gas suspension system
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. Simultaneously, 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 foot valve , generates the bump damping.
This is how the piggyback canister attached to the rear shock absorber (Mono-shock/Dual-shocks) of your ride helps this Nitrox the efficiency of the damper throughout the ride irrespective of the riding condition. So, folks when you see these Nitrox filled shock absorbers featured on your motorcycle, feel privileged as they are indeed a better technology . the bi-tube damper, the mono-tube shock has no reservoir tube. Still, a possibility is needed to store the oil that is displaced by the rod when entering the cylinder. This is achieved by making the oil capacity of the cylinder adaptable.
Therefore the cylinder is not completely filled with oil; the lower part contains (nitrogen) gas under 20 â€“ 30 bar. Gas and oil are separated by the floating piston. When the piston rod is pushed in, the floating piston is also forced down by the displacement of the piston rod, thus slightly increasing pressure in both gas and oil section. Also, the oil below the piston is forced to flow through the piston. The resistance encountered in this manner generates the bump damping.