DISPOSITIF DE COMMANDE POUR LA PROPULSION D'UN VEHICULE DE TRAVAIL, D'UN TRACTEUR AGRICOLE PAR EXEMPLE

摘要

A propelling drive control apparatus for a working vehicle comprising hydraulically operable friction clutches, a first clutch control valve for selecting between the friction clutches, and a second clutch control valve connected in series to the first clutch control valve. The second clutch control valve is manually switchable to a declutching position for disengaging the friction clutches, a first clutch engaging position for engaging one of the friction clutches, and a second clutch engaging position intermediate between the declutching position the first clutch engaging position. In this second clutch engaging position one of the friction clutches is operable under a lower hydraulic pressure than in the first clutch engaging position.