Abstract: A travelling vehicle equipped with obstacle detector sensors having, at the front of the vehicle body (1), a noncontact-type obstacle detector sensor (A) and a contact-type obstacle detector sensor (B), and a vehicle speed control device (20) adapted to automatically reduce the vehicle speed from a preset vehicle speed (v.sub.)0) to a predetermined vehicle speed (v.sub.1) when the noncontact-type obstacle detector sensor (A) detects an obstacle, adapted to automatically reset the vehicle speed to said preset speed (v.sub.0) when the sensor (A) does not detect the obstacle any more during such speed reduction, and adapted to automatically stop the travelling of the vehicle immediately when the contact-type obstacle detector sensor (B) detects the obstacle.

Abstract: A multistage change-speed apparatus for a tractor has a running-travel-system change-speed gearing apparatus, a planetary gearing reduction apparatus operatively connected to that apparatus, an intermediary transmission shaft driven by this apparatus, a speed-reduction shaft disposed beneath that shaft, a bevel pinion shaft disposed in parallel with this shaft, an auxiliary change-speed gearing apparatus disposed between these two shafts, and a differential operatively connected to that apparatus. The planetary gearing reduction apparatus is shiftable between the operative state and the inoperative state.

Abstract: A device for tightening an endless element which is trained over driving members and which is accommodated in a drive transmission housing. A regulation member is provided outside the housing for easy adjustment of the tautness or tension of the endless element.

Abstract: Axle case comprising a tube, a substantially semispherical first member integral with the tube and a substantially semispherical second member connected to the first member and rotatable relative thereto.