PURPOSE: To obtain a common use for various machines with a set of drive car, by coupling the drive car having a prime mover or the like and the various machines with a detachably coupleable coupling mechanism.

CONSTITUTION: To couple a drive car 1 to a work machine, firstly a link lever 23 is allowed to make a turning motion against a spring 25 and engaged to a notch of the long groove in a coupling plate 7. Secondly a body of the car is tilted toward front by holding a handle 8, and coupling plates 5, 7 are intruded into between upper and lower pins 18, 21 provided in a coupling frame mounted to the work machine to raise the car body, then a notch 19 is engaged to the pin 18 at the upper side. And then a disengagement of the lever 23 causes its protrusion 24 and notch 22 to hold the pin 21 at the lower side, and a coupling work is completed.