Automatic return mechanism for hydrostatic transmission pressure release valve

In a vehicle having an engine and drive wheels with brakes, the improvement comprising:

• hydrostatic transmission means including
• pump means coupled to a motor means by first and second pressure return lines;
• a hydrostatic fluid supply for said lines;
• a bypass line having bypass valve means interconnecting the pressure return lines,
• said valve means being shiftable between first and second positions for respectively blocking or permitting flow of hydrostatic fluid through the valve means;
• valve control means shiftable between first and second positions and effective to respectively shift the bypass valve means between its first and second positions;
• detent means operatively coupled with the valve control means and moveable between first and second positions,
• said detent means when in its first position being effective to retain the valve control means in its second position,
• and the bypass valve means in its second position wherein fluid flow through the bypass valve means is permitted;
• and
• brake means interconnected with the wheel brakes and the valve control means for moving the detent means to its first position as the wheel brakes are applied.