PURPOSE: To eliminate the abrupt forward lowering of a rolling cab, by employing a rolling link and a rolling stopper for limiting it to couple a hydraulic cylinder with the cab and employing no special hydraulic cylinder and a hydraulic circuit.

CONSTITUTION: A bracket 21 of a cab 20 is fixed through a link 26 to a chassis side bracket 25 while a coil spring 28 and a shock absorber 27 are fixed between them. A hydraulic cylinder 11 is fixed to the chassis 24 and a hooked arm 15 at the tip of its operating rod 13 is fixed through a rolling link 16 to the bracket 21. The rolling of said link 16 is regulated by a stopper 23. Under normal state, the vibration of the chassis is never trasnmitted to the carburetor because of the rolling link. When the cab is rolling, the rolling link 16 will rotate until striking the stopper 23 thereby it will cause no abrupt forward lowering of the cab.