Product Overview This swing hydraulic pump assembly, with part numbers 266-7953 and 259-0784, is the hydraulic power unit specially designed for the swing system of E385C and E390D excavators. It supplies high-pressure hydraulic oil to drive the swing motor assembly. The unit adopts a variable piston structure with precise flow control, wear-resistant alloy materials, and precision machining. It is designed for direct replacement installation and delivers stable output