Hydraulic operating arrangement

A hydraulic apparatus for moving a part relative to a vehicle which comprises:

• a double-acting working cylinder defining first and second working chambers therein,
• a pressure medium source having first and second sides,
• a first line for delivering pressure medium from said first side of said pressure medium source to said first working chamber, said first line including a first unlockable check valve,
• a second line for delivering pressure medium from said second side of said pressure medium source to said second working chamber, said second line including a second unlockable check valve,
• a solenoid controllable proportional pressure regulating valve having an input side and an output side,
• a third line for delivering pressure medium from said first working chamber to said input side of said pressure regulating valve,
• a fourth line for delivering pressure medium from said second working chamber to said input side of said pressure regulating valve,
• a fifth line for delivering pressure medium from said output side of said pressure regulating valve to said first line between said first check valve and said first working chamber, said fifth line including a third check valve, and
• a sixth line for delivering pressure medium from said output side of said pressure regulating valve to said second line between said second check valve and said second working chamber, said sixth line including a fourth check valve.