To stably maintain the state of four wheel drive and thereby improve power transmission reliability in a free wheel hub configured so that the state of two wheel drive is maintained by applying a magnetic attraction force by a magnet.
The outer periphery of a diaphragm 13 partitioning the interior of a hub housing 6 into a two wheel drive side negative pressure chamber 21 and a four wheel drive side negative pressure chamber 22 is held from both sides by a sleeve 8 and a diaphragm cover 14. The center part of the diaphragm 13 is held from both sides by an outer reinforcing plate 15 and an inner reinforcing plate 16. The outer reinforcing plate 15 and the inner reinforcing plate 16 are connected to each other by caulking a rivet 17 inserted through the center part. The state of the two wheel drive is maintained by the action in which a magnet 23 mounted on the inner surface of the diaphragm cover 14 attracts the outer reinforcing plate 15. The state of the four wheel drive is maintained by the action in which a magnet 32 fixed on the end surface of a front axle 1 attracts the inner reinforcing plate 16.
Higashio Masahiro
Takayoshi Tagawa