US Patent 7240907 Tricycle crank structure

A tricycle crank structure comprises a wheel axle, a pair of cranks and a pair of pedals. The wheel axle is provided with a pair of non-circular sectional holes at respective ends. The inner wall of each hole is provided with a recess. Each crank has one end pivotally connected to the pedal and another end provided with a connecting section. The connecting section is provided with a tenon to engage with the recess of the hole for quick mounting and dismounting. Each hole may be provided with a pair of through holes, and each crank is provided with an elastic clip for connection.