Electrohydraulic proportional pressure control for open circuit pump

A pump control assembly for controlling a variable displacement hydraulic pump, the pump control assembly comprising:

• a valve block defining a spool bore, the valve block also defining a first port, a second port, and a third port;
• a spool mounted within the spool bore and being movable within the spool bore between a first position where the second port is in fluid communication with the third port and a second position in which the first port is in fluid communication with the second port;
• a first chamber positioned at a first end of the spool;
• a second chamber positioned at a second end of the spool;
• a piston positioned within the second chamber so as to divide the second chamber into a first section and a second section, the first section being positioned between the piston and the second end of the spool;
• a proportional pressure reducing valve mounted within the valve block, the proportional pressure reducing valve being operable in a first state where the third port is in fluid communication with the second section of the second chamber and a second state where the first port is in fluid communication with the second section of the second chamber;
• and
• a stop structure having a positive stop that stops movement of the piston at a stop position.

A pump control assembly for controlling a variable displacement hydraulic pump, the pump control assembly comprising:

• a valve block defining a spool bore, the valve block also defining a first port, a second port, and a third port;
• a spool mounted within the spool bore and being movable within the spool bore between a first position where the second port is in fluid communication with the third port and a second position in which the first port is in fluid communication with the second port;
• a first chamber positioned at a first end of the spool;
• a second chamber positioned at a second end of the spool;
• a piston positioned within the second chamber so as to divide the second chamber into a first section and a second section, the first section being positioned between the piston and the second end of the spool;
• and
• a proportional pressure reducing valve mounted within the valve block, the proportional pressure reducing valve being operable in a first state where the third port is in fluid communication with the second section of the second chamber and a second state where the first port is in fluid communication with the second section of the second chamber.