An auxiliary mechanism includes a lever unit, a spring unit and a positioning unit. One of the units pivotally connects to the upper portion of a main shock absorber strut so as to pivot between a predetermined lower position for take-off and landing and an upper position. Another unit pivotally connects at an upper end to the upper portion of the main shock absorber strut and pivotally connects at a lower end to the first unit. A third unit pivotally connects at a lower end to the bogie beam at an auxiliary pivot and connects at an upper end to the lever. The positioning unit assumes either a contracted state or extended state for taxiing, take-off and landing, and assumes the other state for stowing the landing gear after take-off. The spring unit provides spring resistance to pivotal movements of the bogie beam about the main pivot during taxiing.