PURPOSE: To prevent rolling thus to improve safety by telescoping left/right suspensions independently while interlocking with handle operation when cornering thereby stabilizing chassis position.

CONSTITUTION: Handle operating angle, acceleration, chassis inclination, etc. are detected by means of oil pressure, air pressure, negative pressure, overload meters and microswitch to extend suspension at the inside of slewing direction while to contract the outside suspension thus to correct inclination of chassis caused through cornering. Consequently rolling of chassis is prevented resulting in improvement of operational stability.