Hydraulic system

Claim 1

IN COMBINATION, AN ENGINE AND A HYDRAULIC STARTING SYSTEM FOR ACCELERATING THE ENGINE TO START CUT-OUT SPEED, THE SYSTEM COMPRISING (A) A VARIABLE DISPLACEMENT HYDRAULIC MOTOR CONNECTED WITH THE ENGINE FOR DRIVING SAME AND HAVING A DISPLACEMENT CONTROL ELEMENT MOVABLE BETWEEN MINIMUM AND MAXIMUM DISPLACEMENT POSITIONS; (B) A SOURCE OF HYDRAULIC FLUID CAPABLE OF DELIVERING FLUID AT A SELECTED ONE OF TWO SUBSTANTIALLY CONSTANT SUPPLY PRESSURES AND AT A RATE THAT VARIES BETWEEN A MINIMUM VALUE AND A MAXIMUM VALUE EQUAL TO THE DEMAND OF THE MOTOR WHEN THE DISPLACEMENT CONTROL ELEMENT IS IN A MAXIMUM DISPLACEMENT POSITION AND THE MOTOR IS OPERATING AT A SPEED LESS THAN STARTER CUT-OUT SPEED; (C) CONDUIT MEANS CONNECTED WITH THE MOTOR AND THE SOURCE FOR LEADINT FLUID FROM THE SOURCE TO AND THROUGH THE MOTOR; (D) MOTOR CONTROL MEANS CONNECTED WITH THE DISPLACEMENT CONTROL ELEMENT AND RESPONSIVE TO THE OPERATING PRESSURE OF THE MOTOR FOR POSITIONING SAID ELEMENT IN THE MAXIMUM DISPLACEMENT POSITION WHEN OPERATING PRESSURE IS ABOVE A PREDETERMINED PRESSURE AND FOR MOVING SAID ELEMENT TOWARD THE MINIMUM DISPLACEMENT POSITION AS OPERATING PRESSURE TENDS TO DECREASE BELOW SAID PREDETERMINED PRESSURE, WHEREBY THE CHANGE IN DISPLACEMENT OF THE MOTOR MAINTAINS MOTOR DEMAND CONSTANT AT SAID MAXIMUM DELIVERY RATE; AND (E) REGULATING MEANS CONNECTED WITH THE MOTOR CONTROL MEANS AND RESPONSIVE TO THE SUPPLY PRESSURE FOR ESTABLISHING A HIGH VALUE FOR SAID PREDETERMINED PRESSURE WHEN THE SOURCE IS DELIVERING FLUID AT THE HIGHER OF SAID TWO SUBSTANTIALLY CONSTANT SUPPLY PRESSURE AND FOR ESTABLISHING A LOWER VALUE FOR SAID PREDETERMINED PRESSURE WHEN THE SOURCE IS DELIVERING FLUID AT THE LOWER OF SAID TWO SUBSTANTIALLY CONSTANT SUPPLY PRESSURES.