Seminar On Nitro Shock Absorbers free PDF Download
Nitro Shock Absorbers-Working Principle
shock absorbers are high quality, nitrogen filled shocks designed and gas charged specifically for each vehicle application. The addition of nitrogen under pressure limits the foaming effect and increases efficiency.
PRINCIPLE OF OPERATION
The damping mechanism of a shock absorber is viscous damping. Viscosity is the property of a fluid by virtue of which it offers resistance to the motion of one layer over the adjacent on. The main components of a viscous damper are cylinder, piston and viscous fluid. There is a clearance between the cylinder walls and the piston. More the clearance more will be the velocity of the piston in the viscous fluid and it will offer less value of viscous damping coefficient. The basic system is shown below. The damping force is opposite to the direction of velocity.
SHOCK ABSORBER ACTION
Shock absorbers develop control or resistance by forcing fluid through restricted passages. A cross-sectional view of a typical shock absorber is shown below. Its main components and working is also given below.
The upper mounting is attached to a piston rod. The piston rod is attached to a piston and rebound valve assembly. A rebound chamber is located above the piston and a compression chamber below the piston. These chambers are full of hydraulic fluid. A compression intake valve is positioned in the bottom of the cylinder and connected hydraulically to a reserve chamber also full of hydraulic fluid. The lower mounting is attached to the cylinder tube in which the piston operates.
During compression, the movement of the shock absorber causes the piston to move downward with respect to the cylinder tube, transferring fluid from the compression chamber to the rebound chamber. This is accomplished by fluid moving through the outer piston hole and unseating the piston intake valve.
During rebound, the pressure in the compression chamber falls below that of the reserve chamber. As a result, the compression valve will unseat and allow fluid to flow from the reserve chamber into the compression chamber. At the same time, fluid in the rebound chamber will be transferred into the compression chamber through the inner piston holes and the rebound valve.
WHY GAS FILLED SHOCK ABSORBERS?
The rapid movement of the fluid between the chambers during the rebound and compression strokes can cause foaming of the fluid. Foaming is the mixing of free air and the shock fluid. When foaming occurs, the shock develops a lag because the piston is moving through an air pocket that offers up resistance. The foaming results in a decrease of the damping forces and a loss of spring control.
During the movement of the piston rod, the fluid id forced through the valuing of the piston. When the piston rod is moving quickly, the shock absorbers oil cannot get through the valuing fast enough, which causes pressure increases in front of the piston and pressure decreases behind the piston. The result is foaming and a loss of shock absorber control. The need for a gas filled shock absorber arises here.
TYPES OF GAS FILLED SHOCK ABSORBERS
- Twin– tube with low pressure gas.
- Single- tube with high pressure gas.
The main components are:
- Outer tube, also called reservoir tube.
- Inner tube, also called cylinder
- Piston connected to a piston rod
- Bottom valve, also called foot valve
- Upper and lower attachment
ADVANTAGES OF NITRO SHOCKS
- Because the high pressure eliminates aeration (foaming), action is always is immediate.
- The low mass of gas and the single tube further improves response time.
- Since there is no outer tube, cooling is much better which gives a drastic reduction in fade. Thus more consistent handling and control.
- Single-tube construction also allows for a larger internal working area, reducing stress and fatigue for better durability.
- De Carbon’s mono disc valving system features a single moving part that drastically reduces inertia and friction, to improve durability and performance.
- Better cooling of the mono tube design results in lower operating temperatures and thus longer life.
- The viscosity of hydraulic fluid changes as temperature changes. This may because of climate, season (summer/winter) or heavy duty (motorway cruising).
- The high pressure gas compensates immediately and automatically for changes in viscosity.
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