Expandable hydraulic valve stack

A method of expanding a hydraulic valve stack having at least one permanent valve assembly connected to a base, the method comprising:

• removing an end plate from the hydraulic valve stack while the at least one permanent valve assembly remains connected to the base;
• operatively connecting an optional valve assembly to the base;
• and
• reassembling the end plate.

A method of maintaining a hydraulic valve stack having at least one permanent valve assembly and at least one optional valve assembly connected to a base, the method comprising:

• removing one of an end plate and an inlet cover from the hydraulic valve stack while at least one of the at least one permanent valve assembly and the at least one optional valve assembly remains connected to the base;
• accessing one of the at least one permanent and the at least one optional valve assembly;
• and
• reassembling the one of the end plate and the inlet cover.

A work machine, comprising:

• a source of pressurized fluid;
• a reservoir;
• at least one permanent fluid actuator;
• at least one optional fluid actuator;
• and
• a hydraulic valve stack in fluid communication with the source of pressurized fluid, the reservoir, the at least one permanent fluid actuator, and the at least one optional fluid actuator, the hydraulic valve stack including:
• a base having a first mounting surface and a second mounting surface, the base being connectable to the work machine and having at least one fluid passageway extending through the base from the first mounting surface to the second mounting surface;
• a permanent valve assembly configured to control the at least one permanent fluid actuator, being connectable to the first mounting surface of the base, and having at least one fluid passageway in communication with the at least one fluid passageway of the base;
• and
• an optional valve assembly configured to control the at least one optional fluid actuator, being connectable to the second mounting surface of the base, and having at least one fluid passageway in communication with the at least one fluid passageway of the base.