Function of a Shock Absorber:
The function of a shock absorber is to keep the tyres in firm contact with the road surface and to control spring and suspension movement of the vehicle.
Worn Shock Absorbers:
A worn shock absorber can effect the stopping distance of a vehicle by 2 metres (at approximately 50km/h). This variance could be the difference between a life or death situation.
When driving through bends, worn or leaking shock absorbers will cause the vehicle to sway excessively to the left or to the right, making it more difficult to control the vehicle. Poor damping force will also cause the tyres to bounce, causing poor road contact while the vehicle is in motion. Poor road contact will lead to tyre wear, creating flat spots on the tyre surfaces. Flat spots on the tyres make a humming-type sound while driving. This sound is often misinterpreted as a wheel-bearing noise. In order to identify this type of wear on the tyre, one has to run one’s hands over the surfaces of the tyres to feel for these flat spots.
Signs of Worn Shock Absorbers:
- Vehicle is unstable when cornering, due to an excessive swaying motion
- Nose diving or a rocking noise heard when braking
- The rear of the vehicle squats on pull-off
- Un-even tyre wear (flat spots)
- Shock absorbers leaking oil, either due to damage or normal wear and tear (oil by-passing the multi-lip oil seal, rendering the shock absorber ineffective with no damping force)
Recommended Shock Absorber Replacement:
Shock Absorber replacement is recommended at 80 000km. This is because the three-stage valve, made up of metal discs, works approximately 1500 times per kilometre. At 80 000km the valve has worked approximately 120,000,000 times. When replacing shock absorbers it is important to also inspect the shock mountings and protection kits and replace these if necessary.
Advantages of Using Tyndall Shock Absorbers:
- Tyndall shocks and struts are ISO/TS-approved
- Tyndall shocks and struts are Certified by DQS in Germany
- Tyndall shocks and struts carry a 5-year warranty
Internal Components of the Tyndall Shock Absorber:
Three-Stage Valve (used for precision damping control during rebound and compression stages):
The three-stage valve, made up of metal discs, comprises various disc thicknesses. This valve restricts the oil flow to a certain point, at different pressures during the compression and rebound strokes. The oil then passes through ports and orifices of the three-stage valve, and base valve. This creates the damping force of the shock absorber.
An Easy Way to Understand the Workings of the Three-Stage Valve:
The first stage is constantly working while driving on relatively flat road surfaces. If the road surface becomes more uneven, the second stage begins to work. If the road surface becomes extremely uneven (such as a bumpy sand road) the third stage begins to work.
All-weather mineral oil is used for almost constant viscosity , which is tested at -30 and 80 degrees Celsius. While the shock absorber is working, heat is created (kinetic energy) from the internal moving parts. This heats the oil and forms fine, frothy bubbles (aeration). Nitrogen gas, mixes with, and cools, the oil. The balance of heat is dissipated through the shock absorber body.
A hardened, chromed piston rod assures lower friction and longer life of the multi-lip oil seal. The multi-lip oil seal keeps the mineral oil and Nitrogen gas from escaping. This prevents any external contaminants entering the shock absorber. A wear-resistant teflon ring is attached to the hardened, chrome rode and is used on the three-stage valve. . This prevents friction, or by-passing of oil, during the compression and rebound strokes.
Changes in image below: 3-STAGE VALVE
The most frequently used shock absorber or strut is the twin-tube design. The twin-tube comprises an inner and an outer cylinder, the outer being the oil and gas reservoir. The three-stage valve works in conjunction with the base valve during compression and rebound strokes: pushing oil through the base valve into the outer cylinder (on the compression stroke) and pulling oil back through the base valve (on the rebound stroke).