Product Overview This hydraulic main pump, identified by part numbers 334-9990, 295-9678, 311-9552, and 10R-2520, is the primary hydraulic power unit engineered specifically for the E390D excavator hydraulic system. It delivers high-pressure hydraulic oil to drive the boom, arm, bucket, travel, and swing assemblies. Built on a variable piston structure, the pump combines precise flow control, wear-resistant alloy materials, and precision machining. It is designed for direct