ZX330-3 ZX350-3 EX300-2 4438338 4642947 HPV145 Hydraulic Pump Rear Cover Back Cap Compatible with Hitachi
1. Product Overview & Wholesale Price Range
The Hitachi HPV145 Hydraulic Main Pump Rear Cover / End Cap (OEM Part # 4438338 / 4642947 / HPV145) is a high-density ductile iron casting precision-machined with bimetallic valve plate contact surfaces and regulator mounting ports, designed for 30-to-35-ton heavy excavator hydraulic pump overhauls.
- Factory Wholesale Price: $180 – $420 USD (Direct manufacturer pricing — Save up to 50% vs regional dealer markups)
- Material Specifications: High-tensile nodular cast iron + CNC micro-lapped distributor mating face
- MOQ & Bulk Discount: 1 Unit (Tiered wholesale discounts available for hydraulic repair shop batch orders)
- Lead Time: 1–3 business days (Large factory stock ready for immediate worldwide dispatch)
- Warranty: 12 Months full replacement warranty against casting defects and pressure cracks
2. Application Worksite Checklist (施工场景清单)
Precision-machined surfaces engineered to maintain zero internal oil bypass under harsh jobsite conditions:
- Heavy Open-Pit Quarrying & Mining: Restores maximum hydraulic working pressure up to 350 Bar for rapid rock loading on Hitachi ZX350-3 excavators.
- Deep Foundation Excavation & Earthmoving: Micro-finished mating faces ensure zero pressure drop during long-hour continuous digging cycles.
- Highway Infrastructure & Heavy Trenching: Precision-drilled pilot and drain galleries allow smooth regulator spool response without pressure surges.
- Demolition & Heavy Breaker Operations: Heavy-wall ductile iron housing absorbs severe hydraulic pressure shockwaves from hammer attachments.
3. Hydraulic Pump Rear Cover Troubleshooting & Diagnostic Guide (泵后盖常见故障排查)
If your HPV145 hydraulic main pump is exhibiting leakage or pressure loss during overhaul, check the symptoms below:
- Fault 1: Severe Scoring & Grooves on the Rear Cover Mating Surface (后盖配流拉伤拉沟)
Root Cause: Contaminated hydraulic fluid metallic debris grinding between the cylinder block face and the rear cover distributor seating.
Solution: Replace with a new precision-lapped HPV145 pump rear cover (OEM 4438338) to restore a 100% tight hydraulic seal. - Fault 2: High-Pressure Oil Bypass & Thermal Pressure Loss After 1 Hour (热车掉压/内泄串油)
Root Cause: Micro-warpage or thermal clearance distortion on the rear cover face under long continuous heavy loading.
Solution: Install our heat-treated ductile iron HPV145 rear cap to maintain stable zero-bypass performance under hot oil conditions. - Fault 3: Stripped Threaded Holes for Regulator Mounting Bolts (调节器螺纹孔孔滑丝)
Root Cause: Over-torquing during previous maintenance overhauls or severe fatigue vibration from hydraulic hammer attachments.
Solution: Replace the damaged back cover casting with a factory-new HPV145 end cap with reinforced thread depth. - Fault 4: Micro-Cracks & External Oil Leakage From Pump End Casing (后盖外壳开裂漏油)
Root Cause: Extreme hydraulic pressure spikes exceeding 400 Bar or fatigue failure in old cast housings.
Solution: Replace with our heavy-wall reinforced nodular cast iron HPV145 rear cover assembly.
4. Hot Machinery Replacement Parts Recommendation (5大品类热门推荐表)
Explore our factory-direct replacement hydraulic components compatible with major global excavator brands:
| Category (品类) | Machine Model (适用型号) | OEM Part Number (零件号) | Compatibility (适配品牌) |
|---|---|---|---|
| Hydraulic Pump Rear Cover | ZX330-3 / ZX350-3 | 4438338 / 4642947 / HPV145 | Compatible with Hitachi |
| Hydraulic Pump Repair Kit | SK330-8 / SK350-8 | YN15V00018F1 / MSF340VP | Compatible with Kobelco |
| Hydraulic Pump Repair Kit | PC60-5 / PC60-6 / PC60-7 | 708-1W-00030 / HPV35 | Compatible with Komatsu |
| Hydraulic Main Pump | SY285C / SY305C / XE270D | 11422791 / K5V140DTP | Compatible with Sany XCMG |
| Hydraulic Main Pump | CAT 320C / 320D | 200-3269 / SBS120 | Compatible with Cat-erpillar |
| Slewing Motor Assembly | SK120-5 / SH120 | YN15V00001F1 / MSG-85P | Compatible with Kobelco Sumitomo |
| Diesel Engine Assembly | EX120-5 / ZX120 | 8-97100-388-0 / 4BG1T | Compatible with Isuzu Hitachi |
5. Frequently Asked Questions & Technical Support (QA 问答专区)
Q1: How do I verify if this HPV145 rear cover fits my Hitachi ZX330-3 or ZX350-3 main pump?
A: Check your original main pump cast tag for OEM numbers 4438338, 4642947, or HPV145 stamp. You can also send us clear photos of your rear cover mounting ports for instant verification.
Q2: Is the distributor valve plate contact face pre-lapped and ready for immediate assembly?
A: Yes, every HPV145 rear cover undergoes CNC precision machining and flat-surface micro-lapping to guarantee airtight, zero-bypass fitment with the valve plate and cylinder block.
Q3: What material is used for this HPV145 hydraulic pump rear cover casting?
A: It is manufactured using high-strength nodular iron (QT500-7) with high thermal shock resistance and high pressure tolerance up to 380 Bar.
