Power transmission unit

The utility model provides a both sides and with the initiative gear engagement that power transmission unit, characterized by power output shaft support with the support respectively the adaptation fix on the supporting seat, the flywheel passes through power output shaft to be installed on power output shaft supports, four recess pulley adaptation ann was put up on the support to the rack, the flywheel passes through drop bar and rack frame adapter coupling, power input shaft supports both ends and fixes on the support, the driving gear passes through power input shaft to be installed in the power input shaft support, two driven gear adaptation respectively installs at the driving gear the utility model discloses can keep under the input rpm precondition the same with output speed, improve the effect of driving force 50%.