Neumek Shanghai Corporation is CHINA EXCLUSIVE DISTRIBUTOR of 4wd set and environmental protection two-cycle engine. Related products and technology authorized and sold as follows: 1)4wd set, 2)environmental protection two-cycle engine. 4wd set: include On/Off Adjustable switch front and rear differential; can be used in ATV,tricycle or motor refitted into tricycle. usage: can be used in ATV, Tricycle, and motor refitted into tricycle Function: while power is transmissed to both sides of the rear half-shaft, it allows them to revolve at different speed in order that two sides of the rear axle try to make the no equal-space in the form of pure rolling. The differential equipment may get differential gear locked, cause the two sides of differential mutually miss the differential effect, in other words when the differential installment used, the power from engine to driving axle be allowed averagely passed to two driving gears completely, but cannot have the differential motion the phenomenon, thus guarantee engine power pass to four wheels, finally ensure the 4WD vehicle cross country Guarantee the driving influence to display normally, absorb rotational speed difference from the turning. Then enable the vehicles to make a turn smoothly and reduce tire and the ground friction. Also own the switch function.