Hydraulic system for a multi-function machine

A hydraulic system for an agricultural machine, the hydraulic system comprising:

• a tank operable to store a fluid;
• a first fixed displacement pump having a first pump output;
• a second fixed displacement pump having a second pump output;
• a first actuator having a first required flow rate to perform a first function;
• a second actuator having a second required flow rate to perform a second function, wherein the first required flow rate is greater than the second required flow rate;
• a combined flow control valve controllable between a first state and a second state;
• wherein the combined flow control valve connects fluid communication between the first fixed displacement pump and the tank when the combined flow control valve is disposed in the first state, to direct the first pump output to the tank so that only the second pump output is directed to the second actuator to provide the second required flow rate for the second function of the second actuator;
• wherein the combined flow control valve disconnects fluid communication between the first fixed displacement pump and the tank when the combined flow control valve is disposed in the second state to combine the first pump output and the second pump output such that the combined first pump output and the second pump output is directed to the first actuator to provide the first required flow rate for the first function of the first actuator;
• a first actuator apply valve disposed between the second fixed displacement pump and the first actuator, wherein the first actuator apply valve is controllable between a first state blocking fluid communication in a direction moving from the second fixed displacement pump toward the first actuator, and a second state allowing fluid communication between the second fixed displacement pump and the first actuator;
• and
• a fluid passage interconnecting the first actuator apply valve and the first actuator, and a pilot supply line interconnecting the fluid passage and a hydraulic actuated pilot of the combined flow control valve, whereby a portion of the second pump output flows through the pilot supply line to the hydraulic actuated pilot of the combined flow control valve to actuate the combined flow control valve into the second state of the combined flow control valve when the first actuator apply valve is disposed in the second state of the first actuator apply valve, thereby allowing the first pump output to combine with the second pump output.

A windrower comprising:

• a frame;
• a prime mover operable to generate a torque;
• a hydraulic system including:
• a tank operable to store a fluid;
• a first fixed displacement pump having a first pump output;
• a second fixed displacement pump having a second pump output;
• a first actuator having a first required flow rate to perform a first function;
• a second actuator having a second required flow rate to perform a second function, wherein the first required flow rate is greater than the second required flow rate;
• a combined flow control valve controllable between a first state and a second state;
• wherein the combined flow control valve connects fluid communication between the first fixed displacement pump and the tank when the combined flow control valve is disposed in the first state of the combined flow control valve, to direct the first pump output to the tank so that only the second pump output is directed to the second actuator to provide the second required flow rate for the second function of the second actuator;
• wherein the combined flow control valve disconnects fluid communication between the first fixed displacement pump and the tank when the combined flow control valve is disposed in the second state of the combined flow control valve to combine the first pump output and the second pump output such that the combined first pump output and the second pump output is directed to the first actuator to provide the first required flow rate for the first function of the first actuator;
• a first actuator apply valve disposed between the second fixed displacement pump and the first actuator, wherein the first actuator apply valve is controllable between a first state blocking fluid communication in a direction moving from the second fixed displacement pump toward the first actuator, and a second state allowing fluid communication between the second fixed displacement pump and the first actuator;
• a fluid passage interconnecting the first actuator apply valve and the first actuator, and a pilot supply line interconnecting the fluid passage and a hydraulic actuated pilot of the combined flow control valve, whereby a portion of the second pump output flows through the pilot supply line to the hydraulic actuated pilot of the combined flow control valve to actuate the combined flow control valve into the second state of the combined flow control valve when the first actuator apply valve is disposed in the second state of the first actuator apply valve, thereby allowing the first pump output to combine with the second pump output;
• an orifice restriction disposed within the pilot supply line;
• a check valve disposed between the first fixed displacement pump and the first actuator, wherein the check valve is operable to allow fluid flow in a direction moving from the first fixed displacement pump toward the first actuator, and wherein the check valve is operable to block fluid flow in a direction moving from the first actuator toward the first fixed displacement pump;
• and
• a second pump exhaust valve controllable between a first state connecting fluid communication between the second fixed displacement pump and the tank, and a second state blocking fluid communication between the second fixed displacement pump and the tank in a direction moving from the second fixed displacement pump toward the tank.