A wrong hydraulic pump doesn't just fail to fit — it can damage your entire hydraulic system, void warranties, and leave your excavator idle for weeks while you wait for the correct replacement. Yet across our global customer base of dealers, repair shops, and equipment owners, hydraulic pump mis-selection remains one of the most common and costly sourcing errors we see.
This guide covers everything you need to confirm before purchasing a hydraulic main pump for your excavator — whether you're sourcing for a Hitachi ZX, Komatsu PC, Caterpillar 320, or any other major brand machine.
The single most reliable starting point is the OEM part number from the original pump's nameplate or your machine's parts manual. Even small variations in a part number — a single letter or digit — can indicate a completely different displacement rating, port configuration, or shaft specification.
Where to find the part number:
Caution: Never source purely by machine model alone (e.g., "Hitachi ZX200"). The same model may have been produced across multiple years with different pump specifications. Always cross-reference with the part number.
Hydraulic pump displacement — measured in cubic centimeters per revolution (cc/rev) — determines the flow rate delivered to your hydraulic system. Installing a pump with the wrong displacement will cause:
Common displacement ranges by machine class:
| Machine Class | Typical Models | Main Pump Displacement |
|---|---|---|
| Mini (1–6 ton) | Komatsu PC35, Hitachi ZX35 | 18–40 cc/rev |
| Medium (13–25 ton) | Hitachi ZX200, Komatsu PC200, CAT 320 | 90–130 cc/rev |
| Large (30–50 ton) | Hitachi ZX350, Komatsu PC360, CAT 374 | 145–250 cc/rev |
| Mining (50+ ton) | Hitachi ZX490, Komatsu PC490 | 250–400+ cc/rev |
The pump shaft must physically connect to the engine's power take-off (PTO). Shaft mismatches are a common reason pumps "don't fit" even when the displacement and part number look correct. Key shaft parameters to check:
Hydraulic ports (inlet, outlet, drain, pilot) must match both the size (BSP/SAE/ORFS thread standard) and the physical position/orientation on the pump body. Even if a pump is hydraulically identical, rotated or mirrored port configurations can make hose routing physically impossible without major system modifications.
Always request a dimensional drawing or compare port positions directly with your existing pump before ordering.
A pump's rated maximum pressure (measured in bar or PSI) must equal or exceed your system's operating pressure. Installing a pump rated below your system's relief pressure will cause premature failure. As a general reference:
| # | Check Item | Why It Matters |
|---|---|---|
| 1 | OEM Part Number | Primary identification — always cross-reference |
| 2 | Displacement (cc/rev) | Controls flow rate; wrong spec = system damage |
| 3 | Shaft Type & Spline Count | Physical fit to engine PTO — not interchangeable |
| 4 | Port Configuration | Thread standard + port position must match |
| 5 | Rated Pressure (bar) | Must meet or exceed system operating pressure |
At RITO Hydraulic, we don't just ship parts — we help you confirm the right part before you order. Our technical team will cross-reference your machine's serial number, existing part number, and application requirements to verify compatibility across our full catalog of OEM-equivalent hydraulic pumps for Hitachi, Komatsu, Caterpillar, Kawasaki, Rexroth, Nachi, KYB, Nabtesco, Toshiba, and JIC machines.
As the authorized distributor of Dongming — one of China's leading hydraulic manufacturers — we maintain verified stock with full traceability documentation, serving customers across Russia, Colombia, Canada, South Africa, Ecuador, Australia, Italy, Spain, and Suriname.
Rito Hydraulic Co., Ltd. is a professional trading company specializing in excavator hydraulic components — hydraulic pumps, main control valves, swing motors, travel motors, and spare parts. As the authorized distributor of Dongming, we serve dealers, repair shops, equipment owners, and wholesale traders across Russia, Colombia, Canada, South Africa, Ecuador, Australia, Italy, Spain, and Suriname.
Contact us: inf@ritohydraulic.com | www.ritohydraulic.com
Leave A Message
Scan to wechat :
