MECHANISM OF SMOOTH STAIR CLIMBING FOR HAND TRUCK/TROLLEY
-The invention provides a manual mechanism for hand truck/trolley to climb stair smoothly WITHOUT LIFTING EFFORT required from the user by utilized combination of rolling, sliding and moment action. User either exerts push force or thrust force during stair climbing, no LIFTING EFFORT requrired.
–Capable to climb stairs without additional core components by comparing with conventional trolley/hand truck. This means potential of no major additional component and assembly cost by having the stair climbing function. –Capable to carry object with length greater than base such as refrigerator by having an additional base as described in details in patent specification. -climb stairs WITHOUT LIFTING EFFORT
hand-truck, platform trolley; -Capable to extend invented stair climbing function to other products such as school bag, wheel chair, laundry basket, mop bucket, luggage, gas tank , mini shopping trolley etc.