1027131 Original Excavator Hydraulic Main Pump Head Cover for ZX200

Part number 1027131 is the original hydraulic main pump housing provided by Hitachi for the ZX200 series 20 ton medium-sized hydraulic excavator. As shown in the picture you uploaded, this component is the "skeleton" and foundation of the hydraulic main pump. Its universal models cover mainstream models such as ZX200-3, ZX200-5G, ZX210-3 in the 20-21 ton class on the same platform, especially suitable for configurations equipped with HPV series (such as HPV102/118) dual plunger pumps. As the core casting of the original factory, all installation reference surfaces, bearing hole positions, and oil passage interfaces have been precision machined, and the fitting tolerance requirements with the rotating components inside the pump (plunger, cylinder body, and distribution plate) are extremely high. It is strictly prohibited to use non-standard secondary factory shells to avoid abnormal noise, increased internal leakage, or early scrapping of the pump body.

This product is a main pump housing made of high-strength gray cast iron (HT250) or ductile iron, which is cast and processed into one piece. The structure is exactly the same as the picture you provided: it has a complex symmetrical structure, with the pump chamber body in the center, bearing seats and interface flanges on the left and right sides, and oil suction ports, oil outlet ports, leakage ports and process holes distributed on the front. It is internally cast with high-pressure oil passages, low-pressure oil passages, and lubricating oil passages. All sealing surfaces and bearing mounting holes are precision bored, milled, and ground, with flatness and coaxiality tolerances controlled within 0.02mm. The surface of the shell is treated with rust prevention (such as spraying or phosphating) to present a matte black color as shown in your picture. The grid like embossing on the cylindrical raised surfaces on both sides aims to increase the frictional force on the contact surface with the connecting piece and may serve as a process identification area. Its core function is to provide high rigidity support for all moving parts, form a closed chamber, and ensure precise separation of high and low pressure oil circuits.

Installation specifications: 1 Cleaning: Before installation, all oil passages inside the housing must be thoroughly cleaned with specialized cleaning agents and high-pressure air, and inspected with an endoscope to ensure that there are no casting sand particles or iron filings remaining. 2. Inspection: Focus on checking whether each bearing seat hole has any scratches or corrosion, and whether each joint surface (especially the joint surface with the valve plate) has any scratches or corrosion. 3. Assembly: When installing the internal components of the pump (cylinder body, plunger, bearings, etc.) into the housing, lubricating grease should be applied to the outer ring of the bearing for positioning, and special installation tools should be used to ensure smooth pressing. 4. Tightening: Tighten all pump body connecting bolts in three steps according to the diagonal sequence and torque specified in the maintenance manual (usually 60-80 N · m, depending on the bolt specifications).