Stretchable Baby Stroller / Baby stroller

The stretchable baby stroller is designed with its main supporting shaft to be scalable structure based on the principle of pressure structure, to control the front wheel. The front wheel is withdrawn when going upstairs, and the back wheels are lifted up to follow up. And the front wheel is extent to the ground directly when going downstairs, and the back wheels are pushed forward to follow up. The stretchable structure allows the stroller to go stably on the stairs. And it is easy to control even just by one person.