The calibration of the shock absorber is the resistance that needs to be set against the suspension, that is, the force needed to reduce or dampen the oscillation and movement of the suspension set.
Technically, this is referred to as the damping characteristic.
To define damping we need to take into account the needs of the user and analyse any faulty absorbers: to adjust damping we act on the two valve units inside the shock absorber body.
Essentially, adjustment is performed by widening or narrowing the holes for the passage of oil in the plunger or by acting on the discs that allow passage of oil inside the piston:
the narrower these passages, the stiffer the calibration; widening the passages makes calibration softer.
The terms «stiff» and «soft» refer to the movement of the shock absorber and define the difficulty with which it opens or closes.
Calibration can be illustrated graphically in a number of ways:
classic linear calibration has a progressive, rising pattern
while here we can see a classic ‘toggle’ calibration pattern, like this…extension and compression…and then the classic helical spring calibration, which has a more curved form, which is the most classic of the calibration types developed so far.
Calibration must be effected so it properly matches the elastic elements of the suspension (pneumatic springs, helical springs or leaf springs); it must also take road conditions into account.
To define calibration and set it as requested by the customer, at Sabo we use an MTS system test bench; here we test a prototype shock absorber to simulate movement of the suspension with the shock absorber. Just take a look at our video on bi-frequency tests.