To regulate steep turn of a frame body at the time of high speed travelling by constituting it to regulate a steering operation range of a steering operation means within a first steering operation range by driving a steering operation range regulating means by a control means in the case of detecting car speed higher than a previously set speed area.
An electric current value of a signal to output to each of electric working means 24L, 24R to actuate each of cam plate angle control members from a control means is changed in the case when a car speed detection means detects, for example, car speed higher than a previously set speed area (for example, 10km). Sensitive speed of a frame body against revolutional operation of a handle 36 is lowered by reducing working speed of each of the electric working means 24L, 24R. Consequently, it is possible to prevent quick turning motion of the frame body at the time of high speed travelling and to secure safety favourably.
SHIMADA TAKANOBU
FUJIKI KATSUMI
SEIREI IND