The Cat Excavator hydraulic system series of 3066, 3116, 3306, 3406, 3408, S6K, S4K, 3304, C9, C7, C12, C13, E70, E120B, E200B, E240, E240B, 320, 320B, 320C, 320 needs hydraulic pressure cartridge valves with the characteristics of the high flow rate, pressure and shock resistance, especially small and light weight in the compact hydraulic system.