Such shock absorbers are therefore designed to act during lowering of the landing gear when the linear actuator associated with the leg of the landing gear is engaged.
So long as the landing gear lowering operation takes place normally under drive from the associated linear actuator, and in particular from an electromechanical actuator, the actuator itself provides natural braking for the lowering of the landing gear.
In contrast, in the event of a mechanical breakdown in the auxiliary power generation system of the aircraft (which breakdown may be local or more generalized), the actuator is declutched and therefore no longer provides the resistance that is available in normal operation. Under such circumstances, it should nevertheless be possible to perform emergency lowering of the landing gear without damaging its components, i.e. it then appears necessary to be able to bring into play means capable of providing the now-lacking braking, particularly at the end of the down stroke of the landing gear.