Gear pump
Tandem Hydraulic Gear Pump 2PDF+1PUF
Hengyuhang Tandem Hydraulic Gear Pump 2PDF+1PUF Series is a versatile dual-stage external gear pump pairing a Group 2 primary stage with a Group 1 auxiliary stage to power differential flow circuits with high volumetric efficiency and pressure up to 300 bar.
| Applications of Hengyuhang Tandem Hydraulic Gear Pump 2PDF+1PUF Series
This tandem gear pump combination is specifically engineered for multi-circuit mobile and industrial machinery where primary working hydraulics and auxiliary control lines operate from a single prime mover. Typical applications include wheel loaders, backhoes, agricultural tractors, telescopic handlers, municipal maintenance vehicles, refuse trucks, and centralized electro-hydraulic power units requiring dedicated steering, pilot joystick, or cooling fan circuits alongside main cylinder actuators.
| Key Technical Specifications
Product Model: Hengyuhang Tandem Hydraulic Gear Pump 2PDF+1PUF Series
Brand Replacement: Marzocchi, Danfoss, Rexroth, Parker OEM or as requested.
Displacement: Stage 1 (2PDF): 4.0 to 30.0 cm³/rev; Stage 2 (1PUF): 0.8 to 8.0 cm³/rev
Rotation Direction: Clockwise (D), counter-clockwise (S)
Speed Range: Min. speed 500 to 700 r/min; Max. speed 3000 to 3500 r/min
Peak Pressure: 210 to 300 bar (3,045 to 4,350 psi)
- Description
- Tecspecs
- Brand & Reference
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| Overview of HENGYUHANG Tandem Hydraulic Gear Pump 2PDF+1PUF Series
The HENGYUHANG 2PDF+1PUF Series combines a robust Group 2 (2PDF) primary hydraulic gear pump with a precision Group 1 (1PUF) secondary mini gear pump on a rigid through-drive configuration. This differential multi-flow architecture allows equipment designers to supply high-volume hydraulic flow to main actuators (such as boom, bucket, or travel motors) while simultaneously delivering an independent lower-volume flow for steering priority, pilot control, brake boosting, or oil-cooler fan drive—all driven by a single engine PTO or electric motor. The unified assembly eliminates the need for separate prime movers, split gearboxes, or inefficient throttling flow divider valves, saving valuable installation space and improving overall system energy efficiency.
Both pump stages feature high-strength extruded aluminum alloy housings (with optional heavy-duty ductile cast iron front and rear covers), precision-hobbed case-hardened steel gears, and hydrostatic thrust balance plates that provide dynamic axial compensation. Stage 1 (2PDF) covers 10 nominal displacements from 4.0 to 30.0 cm³/rev operating at rated continuous pressures up to 250 bar (3,625 psi) and peak spike pressures up to 300 bar (4,350 psi). Stage 2 (1PUF) covers 11 nominal displacements from 0.8 to 8.0 cm³/rev with peak pressure capability up to 300 bar. Available with separate suction ports or an integrated common suction port for simplified tank suction lines, the 2PDF+1PUF series incorporates standardized European 4-bolt rectangular flanges (pilot Ø 36.5 mm), European diamond 2-bolt flanges, and SAE "A" 2-bolt flanges, providing complete 1:1 drop-in interchangeability across 27 global hydraulic brands.
| Dimension of HENGYUHANG Tandem Hydraulic Gear Pump 2PDF+1PUF Series
[Drawing placeholder — insert the dimensional drawing screenshot here]
Interface data needed with the drawing:
| Item | Value |
|---|---|
| Primary mounting flange options (Stage 1 Front) | 1. European standard 4-bolt rectangular flange (pilot Ø 36.5 -0.025/-0.050 mm with 71.5 × 96.2 mm bolt pitch, 4-Ø 9.0 mm holes) / 2. European standard 2-bolt diamond/rhomboid flange (pilot Ø 36.5 mm or Ø 50.8 mm with 96.0 mm or 106.0 mm bolt centers) / 3. SAE "A" 2-bolt oval flange (pilot Ø 82.55 -0.05 mm / 3.25 in with 106.4 mm / 4.189 in bolt centers) |
| Primary drive shaft options | 1. European 1:8 tapered shaft with woodruff key (M12×1.5 nut, key width 3.15 mm or 4.0 mm) / 2. Cylindrical keyed shaft: Ø 15.87 mm (5/8 in) or Ø 19.05 mm (3/4 in) / 3. Involute splined shaft: SAE 9T, 11T, or DIN 5482 B17×14 |
| Intermediate coupling | Heavy-duty internal splined sleeve connecting Group 2 primary rear shaft to Group 1 secondary drive shaft; rated for full tandem torque transmission. |
| Suction port options (Inlet) | 1. Separate suction: independent inlet ports for Stage 1 (Group 2 flanged/threaded) and Stage 2 (Group 1 flanged/threaded) / 2. Common suction: enlarged single suction port on Stage 1 supplying both pump chambers, minimizing suction hose routing |
| Port configurations | 1. European standard diamond 4-bolt flanged ports (M6 on Stage 2, M6/M8 on Stage 1) / 2. BSPP parallel threaded ports (G 1/2, G 3/4 on Stage 1; G 3/8, G 1/2 on Stage 2) / 3. SAE straight thread O-ring boss ports (UNF/UN threads) |
| Rotation | Clockwise (R / D) or Counter-clockwise (L / S), viewed looking directly at the primary drive shaft. |
| Body construction | High-tensile extruded aluminum alloy body with heavy-duty cast iron or aluminum front mounting flange and intermediate/rear adapter covers. |
| Shaft loading limits | Pure torsional torque transmission required via flexible elastic coupling; zero external axial or radial loads permitted on the primary shaft. |
| Fastener torque limits | Front flange mounting bolts: 45 ±3 Nm; Tie-rod body assembly bolts: 40 ±3 Nm; Port flange screws: M6 = 10 ±1 Nm, M8 = 24 ±2 Nm. |
| Pump Installation Specifications HENGYUHANG 2PDF+1PUF Series
The HENGYUHANG 2PDF+1PUF Series pump utilizes a standardized modular ordering code structure:
Code structure — reference: 2PDF+1PUF — Tandem Hydraulic External Gear Pump Series
| Segment | Meaning | Standard Options & Features |
|---|---|---|
| Series | 2PDF+1PUF | Dual-stage Group 2 (Primary) + Group 1 (Secondary) tandem external gear pump assembly |
| Displacement P1 | 4 to 30 | Primary stage (Group 2): 4.0, 6.0, 8.5, 11.0, 14.0, 16.5, 19.5, 22.5, 26.0, 30.0 cm³/rev |
| Displacement P2 | 0.8 to 8.0 | Secondary stage (Group 1): 0.8, 1.2, 1.6, 2.0, 2.5, 3.2, 4.2, 5.0, 6.0, 7.0, 8.0 cm³/rev |
| Rotation | D / S | D: Clockwise (viewed from drive shaft end); S: Counter-clockwise |
| Drive Shaft | T1 / C1 / S1 | T1: European 1:8 tapered shaft; C1: Cylindrical keyed shaft; S1: Involute splined shaft |
| Mounting Flange | E4 / ED / SA | E4: European 4-bolt rectangular (Ø 36.5 mm); ED: European diamond; SA: SAE A 2-bolt |
| Suction Config | S / C | S: Separate inlets for P1 and P2; C: Common suction port for shared reservoir line |
| Ports | F / B / U | F: European flanged ports; B: BSPP threaded ports; U: SAE O-ring boss ports |
| Seals | N / V | N: Standard NBR (-20 °C to +80 °C); V: FKM / Viton (-10 °C to +150 °C) |
| Reading your replacement code
| Your Target Brand & Series | HENGYUHANG Equivalent | Interchange Verification Notes |
|---|---|---|
| MARZOCCHI GHP2A, ALP2A, GHP2, ALP2, 1PD Series | HENGYUHANG 2PDF+1PUF Series | 100% 1:1 drop-in replacement; identical Group 2 front flange, shaft extensions, port spacing, and Group 1 rear tandem stage |
| DANFOSS SNP1NN, SNP2NN, SNW2NN Series | HENGYUHANG 2PDF+1PUF Series | Direct form, fit, and functional replacement; matching displacement combinations and continuous 250 bar pressure ratings |
| HYDAC PGE102, PGE104 Series | HENGYUHANG 2PDF+1PUF Series | Fully interchangeable mounting pilot, bolt circles, shaft splines, and intermediate through-drive coupling |
| ARGO-HYTOS GP1, GP2, GP3 Series | HENGYUHANG 2PDF+1PUF Series | Exact match across nominal displacements, flange patterns, and pressure capabilities |
| ATOS PFG Series | HENGYUHANG 2PDF+1PUF Series | Plug-and-play installation; matching European 4-bolt/diamond flange and 1:8 tapered shaft options |
| Brevini OT100, OT200, OT300 Series | HENGYUHANG 2PDF+1PUF Series | Direct replacement for multi-function mobile auxiliary and work hydraulic systems |
| BUCHER AP100, AP200, AP212, AP300 Series | HENGYUHANG 2PDF+1PUF Series | High volumetric efficiency, low noise output, and identical mechanical port centerlines |
| BONDIOLI & PAVESI HPLPA1, HPLPA2, HPLPA3 Series | HENGYUHANG 2PDF+1PUF Series | Direct agricultural and industrial tractor drop-in tandem replacement |
| Boden BAP1, BHP1, BAP2, BHP2, BAP3, BHP3 Series | HENGYUHANG 2PDF+1PUF Series | Exact displacement matching, port dimensions, and continuous 250 bar pressure ratings |
| Caproni 10A, 20A, 30A, 10C, 20C, 30C Series | HENGYUHANG 2PDF+1PUF Series | Full mechanical interchangeability; matching shaft keys, flange pilots, and body lengths |
| CASAPPA PLP10, PLP20, PLP30 (Polaris) Series | HENGYUHANG 2PDF+1PUF Series | 100% drop-in tandem replacement for PLP20/10 double pump configurations |
| CONCENTRIC WP300, WP900, WP1500 Series | HENGYUHANG 2PDF+1PUF Series | Equivalent flow delivery, mounting dimensions, and high-speed operation up to 3500 rpm |
| DUPLOMATIC 1P, GP1, GP2, GP3 Series | HENGYUHANG 2PDF+1PUF Series | Direct industrial power unit and machine tool tandem replacement |
| Galtech 1SPA, 2SPA, 3GPG, 3SPA Series | HENGYUHANG 2PDF+1PUF Series | Exact match on mounting flange, shaft tapers, and flanged port pitch |
| GRH 1PF, 2PF, 3PF Series | HENGYUHANG 2PDF+1PUF Series | Direct drop-in match across all Group 2 + Group 1 displacement combinations |
| HANSA-TMP 1SP, 2SP, 3GPG, 3SPA Series | HENGYUHANG 2PDF+1PUF Series | 100% interchangeable fluid power parameters and compact axial body length |
| HESPER HA11, HA2, HA3, CHP1 Series | HENGYUHANG 2PDF+1PUF Series | Direct replacement for mobile work circuits and steering priority systems |
| HONOR 1KH Series | HENGYUHANG 2PDF+1PUF Series | Drop-in dimensional envelope and identical hydraulic port positions |
| HPI P1BAN1, P1BAN2, P1AAN2, P1BAN3, P1AAN3 Series | HENGYUHANG 2PDF+1PUF Series | Exact replacement for French/European mobile machinery standards |
| HYDRONIT E Series | HENGYUHANG 2PDF+1PUF Series | Perfect fit for dual-function electro-hydraulic power packs and compact work circuits |
| JIHOSTROJ P23, J, T3, Q2, UD Series | HENGYUHANG 2PDF+1PUF Series | Exact drop-in replacement for Czech/Central European machinery |
| PARKER PGP505, PGP502, PGP511, PGP517 Series | HENGYUHANG 2PDF+1PUF Series | Direct replacement for Parker Group 2 + Group 1 tandem gear pumps |
| Rexroth AZPB, AZPF, AZPG, AZPN Series | HENGYUHANG 2PDF+1PUF Series | 100% compatible drop-in replacement for Rexroth double gear pumps |
| RONZIO 01ZAG, 01ZBG, 02ZAG, 02ZCG, 02ZLG Series | HENGYUHANG 2PDF+1PUF Series | Exact match on aluminum body geometry, flange pilots, and shaft splines |
| ROQUET 1L0, PLA, GZ, G, GLA, PLC Series | HENGYUHANG 2PDF+1PUF Series | Direct drop-in replacement for Spanish and international agricultural equipment |
| SDH CBD Series | HENGYUHANG 2PDF+1PUF Series | Equivalent pressure levels, displacement sizes, and mounting dimensions |
| VIVOLO X1P, XV-1P, X2P, X3P, XV-2P, XV-3P Series | HENGYUHANG 2PDF+1PUF Series | Direct replacement for Vivoil Group 2 + Group 1 single and tandem external gear pumps |
Techspecs — HENGYUHANG 2PDF+1PUF Series
Stage 1: Group 2 (2PDF) Technical Data
| Displacement Size (cm³/rev) | Rated Continuous Pressure p1 (bar) | Intermittent Pressure p2 (bar) | Maximum Peak Pressure p3 (bar) | Max. Speed (r/min) | Min. Speed (r/min) | Flow Rate @ 1500 r/min (l/min) | Flow Rate @ 3000 r/min (l/min) |
|---|---|---|---|---|---|---|---|
| 4.0 | 250 | 275 | 300 | 3,500 | 700 | 6.0 | 12.0 |
| 6.0 | 250 | 275 | 300 | 3,500 | 700 | 9.0 | 18.0 |
| 8.5 | 250 | 275 | 300 | 3,500 | 600 | 12.75 | 25.5 |
| 11.0 | 250 | 275 | 300 | 3,500 | 600 | 16.5 | 33.0 |
| 14.0 | 250 | 275 | 300 | 3,500 | 500 | 21.0 | 42.0 |
| 16.5 | 230 | 255 | 280 | 3,000 | 500 | 24.75 | 49.5 |
| 19.5 | 210 | 235 | 260 | 3,000 | 500 | 29.25 | 58.5 |
| 22.5 | 190 | 215 | 240 | 2,800 | 500 | 33.75 | 67.5 |
| 26.0 | 170 | 195 | 220 | 2,500 | 500 | 39.0 | 78.0 |
| 30.0 | 160 | 180 | 200 | 2,500 | 500 | 45.0 | 90.0 |
Stage 2: Group 1 (1PUF) Technical Data
| Displacement Size (cm³/rev) | Rated Continuous Pressure p1 (bar) | Intermittent Pressure p2 (bar) | Maximum Peak Pressure p3 (bar) | Max. Speed (r/min) | Min. Speed (r/min) | Flow Rate @ 1500 r/min (l/min) | Flow Rate @ 3000 r/min (l/min) |
|---|---|---|---|---|---|---|---|
| 0.8 | 250 | 275 | 300 | 4,000 | 800 | 1.20 | 2.40 |
| 1.2 | 250 | 275 | 300 | 4,000 | 800 | 1.80 | 3.60 |
| 1.6 | 250 | 275 | 300 | 4,000 | 800 | 2.40 | 4.80 |
| 2.0 | 250 | 275 | 300 | 4,000 | 700 | 3.00 | 6.00 |
| 2.5 | 250 | 275 | 300 | 4,000 | 700 | 3.75 | 7.50 |
| 3.2 | 250 | 275 | 300 | 3,800 | 700 | 4.80 | 9.60 |
| 4.2 | 240 | 265 | 290 | 3,500 | 600 | 6.30 | 12.60 |
| 5.0 | 220 | 245 | 270 | 3,500 | 600 | 7.50 | 15.00 |
| 6.0 | 200 | 225 | 250 | 3,000 | 600 | 9.00 | 18.00 |
| 7.0 | 180 | 205 | 230 | 2,800 | 600 | 10.50 | 21.00 |
| 8.0 | 160 | 185 | 210 | 2,500 | 600 | 12.00 | 24.00 |
| Note: Any Group 2 displacement (4.0–30.0 cm³/rev) can be paired with any Group 1 displacement (0.8–8.0 cm³/rev), such as 2PDF-14+1PUF-3.2, 2PDF-19.5+1PUF-4.2, or 2PDF-22.5+1PUF-2.0. Operating speed of the tandem assembly is governed by the maximum speed of the larger displacement stage. | |||||||
Operating Conditions & Fluid Specifications
| Parameter | Specification | Operating Range & Criteria |
|---|---|---|
| Hydraulic fluid | Mineral hydraulic oil | Mineral-based anti-wear hydraulic oil conforming to DIN 51524 part 2 (HLP) or part 3 (HVLP) |
| Operating fluid temperature | Standard range | -20 °C to +80 °C with NBR seals; -10 °C to +110 °C with optional FKM / Viton seals |
| Operating viscosity | Recommended range | ν = 20 to 80 mm²/s (cSt); Permissible operating range: ν = 10 to 1,000 mm²/s |
| Cold start viscosity limit | Maximum viscosity | ν_max ≤ 1,500 mm²/s at p ≤ 10 bar and speed ≤ 1,500 r/min |
| Suction port pressure | Inlet pressure range | p_inlet = 0.7 to 2.5 bar absolute (0.07 to 0.25 MPa absolute) to prevent suction cavitation |
| Fluid cleanliness level | Maximum contamination | Class 20/18/15 according to ISO 4406 or Class 9 according to NAS 1638 |
| Recommended filtration | Filter rating | Return line filtration β10 ≥ 75 or pressure filtration β25 ≥ 100 |
Advantages — HENGYUHANG 2PDF+1PUF Series
Differential Multi-Flow Circuit Optimization
Provides heavy high-pressure flow (up to 30 cm³/rev) for main lifting or drive circuits alongside dedicated independent flow (up to 8 cm³/rev) for steering, pilot controls, or fan drives from a single power take-off.
Space and Cost-Saving Integration
Eliminates auxiliary pumps, secondary electric motors, and complex throttling flow-divider valves, reducing machine chassis footprint, hydraulic plumbing, and overall bill of materials.
High Volumetric Efficiency (>94%)
Precision gear hobbing and individual hydrostatic pressure-balanced thrust plates in both stages maintain maximum volumetric efficiency across varying operating temperatures and pressures.
Common Suction Capability
Available with an integrated shared inlet port on the primary body that feeds both pump stages, cutting reservoir suction lines and connection fittings in half.
Robust Heavy-Duty Construction
High-tensile extruded aluminum bodies combined with high-grade cast iron front flanges and intermediate adapter plates withstand extreme cyclic shock loads.
Broad Modular Combinations
Ten Group 2 displacements and eleven Group 1 displacements provide over 110 customizable flow ratio combinations to precisely match any dual-circuit requirement.
Reference — HENGYUHANG 2PDF+1PUF Series
Series Architecture
The HENGYUHANG 2PDF+1PUF Series provides modular flexibility across Group 2 and Group 1 displacement sizes:
Stage 1 (2PDF Group 2): 4.0, 6.0, 8.5, 11.0, 14.0, 16.5, 19.5, 22.5, 26.0, 30.0 cm³/rev
Stage 2 (1PUF Group 1): 0.8, 1.2, 1.6, 2.0, 2.5, 3.2, 4.2, 5.0, 6.0, 7.0, 8.0 cm³/rev
Common Popular Combinations: 2PDF-8.5+1PUF-2.0, 2PDF-11+1PUF-3.2, 2PDF-14+1PUF-4.2, 2PDF-16.5+1PUF-4.2, 2PDF-19.5+1PUF-6.0, 2PDF-22.5+1PUF-4.2, 2PDF-26+1PUF-5.0
Target Brand Interchangeability Matrix
The HENGYUHANG 2PDF+1PUF Series is engineered to provide verified 1:1 drop-in replacement across 27 leading international hydraulic brands:
MARZOCCHI: GHP2A, ALP2A, GHP2, ALP2, 1PD Series (Tandem double pump combinations)
DANFOSS: SNP1NN, SNP2NN, SNW2NN Tandem Series
HYDAC: PGE102, PGE104 Series
ARGO-HYTOS: GP1, GP2, GP3 Double Gear Pump Series
ATOS: PFG Series Double Pumps
Brevini: OT100, OT200, OT300 Series Tandem Gear Pumps
BUCHER: AP100, AP200, AP212, AP300 Series Double Pumps
BONDIOLI & PAVESI: HPLPA1, HPLPA2, HPLPA3 Tandem Series
Boden: BAP1, BHP1, BAP2, BHP2, BAP3, BHP3 Series
Caproni: 10A, 20A, 30A, 10C, 20C, 30C Series
CASAPPA: PLP10, PLP20, PLP30 (Polaris PLP20/10) Series
CONCENTRIC: WP300, WP900, WP1500 Series
DUPLOMATIC: 1P, GP1, GP2, GP3 Series Tandem
Galtech: 1SPA, 2SPA, 3GPG, 3SPA Series
GRH: 1PF, 2PF, 3PF Series Double Pumps
HANSA-TMP: 1SP, 2SP, 3GPG, 3SPA Series
HESPER: HA11, HA2, HA3, CHP1 Series
HONOR: 1KH Series
HPI: P1BAN1, P1BAN2, P1AAN2, P1BAN3, P1AAN3 Series
HYDRONIT: E Series Mini Power Pack Pumps
JIHOSTROJ: P23, J, T3, Q2, UD Series
PARKER: PGP505, PGP502, PGP511, PGP517 Series
Rexroth: AZPB, AZPF, AZPG, AZPN Series Double Gear Pumps
RONZIO: 01ZAG, 01ZBG, 02ZAG, 02ZCG, 02ZLG Series
ROQUET: 1L0, PLA, GZ, G, GLA, PLC Series
SDH: CBD Series
VIVOLO: X1P, XV-1P, X2P, X3P, XV-2P, XV-3P Series
Brand Replacement
Quanzhou Hengyuhang Power Technology Co., Ltd. manufactures the 2PDF+1PUF Series conforming precisely to European and SAE standard mounting geometries. Every manufactured unit undergoes computerized end-of-line digital testing, verifying individual stage displacement, continuous rated pressure holding, inter-stage seal barrier isolation, and overall mechanical efficiency. Machine builders, hydraulic system integrators, and plant maintenance managers can directly replace OEM double pumps across all 27 specified brands (MARZOCCHI, DANFOSS, HYDAC, ARGO-HYTOS, ATOS, Brevini, BUCHER, BONDIOLI & PAVESI, Boden, Caproni, CASAPPA, CONCENTRIC, DUPLOMATIC, Galtech, GRH, HANSA-TMP, HESPER, HONOR, HPI, HYDRONIT, JIHOSTROJ, PARKER, Rexroth, RONZIO, ROQUET, SDH, VIVOLO) with zero modifications to drive bells, shaft couplings, or hydraulic line geometry.
Applications — HENGYUHANG 2PDF+1PUF Series
Mobile Construction & Earthmoving Machinery: Primary stage powers main boom and bucket cylinders; secondary stage supplies pilot controls, joystick hydraulics, or cab air-conditioning/fan drive.
Agricultural Tractors & Harvesters: Primary stage operates rear three-point hitch and remote implement remotes; secondary stage drives priority hydrostatic steering and braking circuits.
Telescopic Handlers & Forklifts: Independent fluid supply for boom telescoping/tilting and hydraulic power steering.
Municipal Maintenance & Refuse Vehicles: Dual actuation for compactor packing cycles and bin lifter mechanisms from a single engine PTO.
Stationary Industrial Hydraulic Power Packs: High-flow rapid cylinder traverse (combining both stages) followed by high-pressure low-flow clamping.
Package & Shipping
| Packaging | Individual shock-absorbing custom molded foam in heavy-duty export cartons; moisture-resistant VCI polybags; fumigation-free wooden export pallets for consolidated freight. |
|---|---|
| Selling Unit | Single item (MOQ: 1 piece for standard stock models; low MOQ for customized OEM tandem assemblies). |
| Single Package Size | 35.0 × 24.0 × 22.0 cm (13.78 × 9.45 × 8.66 in) per tandem pump. |
| Single Gross Weight | 4.80 to 7.80 kg (10.58 to 17.20 lbs) depending on displacement combinations. |
| Standard Lead Time | 3–5 business days for stock items; 12–15 business days for volume OEM batch customization. |
| Logistics & Express | Worldwide air express (DHL, FedEx, UPS, TNT), air cargo, maritime shipping (LCL / FCL), and multimodal door-to-door DDP services. |
| Customization Services | Custom laser nameplate marking, private branding, common or separate suction port routing, customized shaft splines, and special seal compounds. |
| Warranty & Support | 12 months comprehensive warranty from dispatch date; full lifetime technical support. |
Why Choose Hengyuhang?
Direct Factory Precision Manufacturing & CNC Excellence: Equipped with multi-axis CNC machining centers, automated high-speed gear hobbing, and ultra-fine micro-lapping equipment, Hengyuhang maintains sub-micron gear profile tolerances (Ra < 0.2 μm) and exact balance plate clearances. This guarantees minimal internal bypass leakage, virtually zero pressure pulsation, and repeatable performance across high-volume production batches.
100% Full-Cycle Multi-Parameter Factory Inspection: Every single hydraulic pump undergoes rigorous end-of-line digital testing before dispatch. Quality checks cover full continuous rated and peak pressure hold, internal bypass leakage verification, inter-stage seal barrier testing, high/low temperature volumetric efficiency testing (>92–94%), and acoustic noise spectrum profiling, ensuring zero-defect delivery.
Seamless 1:1 OEM Drop-In Interchangeability: Conforming precisely to international European standard, SAE, and DIN/ISO mounting configurations, our pumps deliver genuine plug-and-play replacement for MARZOCCHI, DANFOSS, Rexroth, PARKER, and 23 other leading global manufacturers. Machine operators can replace original units without modifying bell housings, drive couplings, or hydraulic line geometry.
Flexible Engineering Customization & Rapid Prototyping: Backed by an experienced in-house hydraulic engineering team, Hengyuhang offers comprehensive bespoke customization, including non-standard mounting flanges, special shaft tapers or splines, common or separate suction port routing, and integrated valve blocks. We support low-MOQ trial orders and agile custom prototyping to resolve obsolescence issues for high-end machinery.
Robust Supply Chain, Extensive Inventory & Fast Global Dispatch: With dedicated casting, extrusion, and precision machining facilities, raw material reserves, and extensive finished inventory across all Group 2 and Group 1 displacement models, standard orders ship within 48 to 72 hours. We partner strategically with major international logistics carriers to provide seamless door-to-door DDP global delivery.
12-Month Comprehensive Warranty & Lifetime Technical Support: All Hengyuhang hydraulic pumps are backed by a complete 12-month factory warranty and dedicated lifetime technical assistance. Our specialized fluid power engineers provide free 24-hour CAD drawing verification, OEM cross-reference confirmation, hydraulic displacement calculations, and system troubleshooting to ensure total operational peace of mind.
Tandem Hydraulic Gear Pump Group 2PDF+1PUF Series (0.8~30 cm³/rev) is a high-performance modular multi-stage external gear pump engineered to supply two distinct hydraulic circuits or provide combined high-low differential flow from a single drive motor. By integrating a heavy-duty Group 2PDF front pump (4.0 to 30.0 cm³/rev) with a compact Group 1PUF rear pump (0.8 to 8.0 cm³/rev) via a high-torque internal intermediate spline coupling, this two-stage combination allows independent displacement sizing and pressure optimization across primary working and secondary auxiliary circuits. Built with high-density extruded aluminium alloy housings, case-hardened micro-finished alloy steel gear sets, and hydrostatic axial pressure-balanced composite DU bushings, the 2PDF+1PUF tandem pump delivers continuous operating pressures up to 250 bar (peak up to 300 bar) on the front stage and up to 230 bar (peak up to 270 bar) on the rear stage. Available with standard European 4-bolt rectangular (Ø36.5 mm pilot) or SAE A 2-bolt oval (Ø82.55 mm pilot) mounting flanges, 1:8 taper or straight keyed drive shafts, and independent or common suction port designs, this series maintains over 94% volumetric efficiency and serves as a direct 1:1 drop-in replacement for CASAPPA POLARIS (PLP20+PLP10), Bosch Rexroth (AZPF+AZPF/AZPB), Marzocchi, Parker, and Danfoss dual gear pumps.
| Applications
The 2PDF+1PUF tandem hydraulic gear pump series is specifically engineered for multi-circuit industrial machinery and mobile equipment requiring simultaneous high-power main operation and low-flow auxiliary or pilot control, including agricultural tractors (main implement lift plus power steering or hydraulic trailer brakes), counterbalance forklifts (main mast elevation combined with power steering or carriage side-shift), compact wheel loaders and mini-excavators, dual-speed high-low hydraulic presses (rapid approach at high flow and high-pressure clamping at low flow), aerial work platforms and telehandlers, garbage compactor trucks, and modular hydraulic power units (HPUs) driving dual independent actuator circuits.
| Key Specifications Overview
| Parameter | Specification |
|---|---|
| Series Architecture | Modular Two-Stage Tandem External Gear Pump (Group 2PDF Front + Group 1PUF Rear) |
| Front Stage Displacement (Group 2PDF) | 4.0 ~ 30.0 cm³/rev (10 standard sizes: 4.0, 6.0, 8.5, 11.0, 14.0, 16.5, 19.5, 22.5, 26.0, 30.0 cm³/rev) |
| Rear Stage Displacement (Group 1PUF) | 0.8 ~ 8.0 cm³/rev (standard sizes: 0.8, 1.1, 1.3, 1.6, 2.1, 2.7, 3.2, 4.2, 4.8, 5.8, 7.0, 8.0 cm³/rev) |
| Continuous Operating Pressure (P1) | Front (2PDF): 170 ~ 250 bar (up to 270 bar for small cc) / Rear (1PUF): 160 ~ 230 bar (up to 250 bar) |
| Intermittent Operating Pressure (P2) | Front (2PDF): 190 ~ 275 bar / Rear (1PUF): 180 ~ 250 bar |
| Max. Peak Pressure (P3) | Front (2PDF): 210 ~ 300 bar / Rear (1PUF): 200 ~ 270 bar (up to 300 bar) |
| Operating Speed Range | 500 ~ 3500 r/min (rated according to paired displacement limits) |
| Volumetric Efficiency | ≥ 94% under rated pressure and temperature envelope |
| Hydro-Mechanical Efficiency | ≥ 89% ~ 92% |
| Housing & Body Material | High-tensile extruded aluminium alloy body with ductile iron/aluminium mounting flange & intermediate adapter |
| Mounting Flange Options | European 4-bolt rectangular (71.5 × 96 mm, Ø36.5 mm pilot) or SAE A 2-bolt oval (106.4 mm centers, Ø82.55 mm pilot) |
| Drive Shaft Options | European 1:8 taper shaft with woodruff key (M12×1.25), Ø15.88 mm / Ø19.05 mm keyed, or splined shaft |
| Intermediate Coupling Mechanism | Heavy-duty internal spline through-drive coupling shaft linking Group 2 and Group 1 gear shafts |
| Suction Port Configuration | Standard separate independent inlet ports for each stage, or shared single suction manifold port |
| Rotation Direction | Clockwise (D / Right-Hand) standard; Counter-Clockwise (S / Left-Hand) available upon request |
| Hydraulic Fluid Compatibility | Mineral-based hydraulic oil (HL / HLP to DIN 51524, ISO VG 32 ~ 46); viscosity 12 ~ 100 mm²/s (cSt) |
| Operating Temperature Range | -20°C to +85°C (standard NBR seals); -15°C to +110°C (optional Viton FKM seals) |
| Cleanliness Requirement | ISO 4406 Class 20/18/15 (NAS 1638 Class 8~9) with return filtration β25 ≥ 75 |
| Front Stage Technical Performance (Group 2PDF)
| Front Model Code | Displacement (cm³/rev) | Operating Pressure (bar) | Rotational Speed (r/min) | Theor. Flow @ 1500 rpm (L/min) | |||
|---|---|---|---|---|---|---|---|
| P1 (Continuous) | P2 (Intermittent) | P3 (Peak) | Max. Speed | Min. Speed | |||
| 2PDF04 | 4.00 | 250 | 275 | 300 | 4000 | 700 | 6.00 |
| 2PDF06 | 6.00 | 250 | 275 | 300 | 4000 | 700 | 9.00 |
| 2PDF08 | 8.50 | 250 | 275 | 300 | 3800 | 700 | 12.75 |
| 2PDF11 | 11.00 | 250 | 275 | 300 | 3800 | 600 | 16.50 |
| 2PDF14 | 14.00 | 250 | 275 | 300 | 3500 | 600 | 21.00 |
| 2PDF16 | 16.50 | 230 | 255 | 280 | 3500 | 600 | 24.75 |
| 2PDF19 | 19.50 | 210 | 235 | 260 | 3200 | 500 | 29.25 |
| 2PDF22 | 22.50 | 200 | 225 | 250 | 3000 | 500 | 33.75 |
| 2PDF26 | 26.00 | 180 | 205 | 230 | 3000 | 500 | 39.00 |
| 2PDF30 | 30.00 | 170 | 190 | 210 | 2800 | 500 | 45.00 |
| Rear Stage Technical Performance (Group 1PUF)
| Rear Model Code | Displacement (cm³/rev) | Operating Pressure (bar) | Rotational Speed (r/min) | Theor. Flow @ 1500 rpm (L/min) | |||
|---|---|---|---|---|---|---|---|
| P1 (Continuous) | P2 (Intermittent) | P3 (Peak) | Max. Speed | Min. Speed | |||
| 1PUF0.8 | 0.80 | 230 | 250 | 270 | 6000 | 1000 | 1.20 |
| 1PUF1.1 | 1.10 | 230 | 250 | 270 | 6000 | 1000 | 1.65 |
| 1PUF-1.3 | 1.30 | 230 | 250 | 270 | 6000 | 1000 | 1.95 |
| 1PUF1.6 | 1.60 | 230 | 250 | 270 | 6000 | 1000 | 2.40 |
| 1PUF2.1 | 2.10 | 230 | 250 | 270 | 6000 | 1000 | 3.15 |
| 1PUF2.7 | 2.70 | 230 | 250 | 270 | 6000 | 800 | 4.05 |
| 1PUF3.2 | 3.20 | 210 | 230 | 250 | 5000 | 800 | 4.80 |
| 1PUF4.2 | 4.20 | 210 | 230 | 250 | 4000 | 800 | 6.30 |
| 1PUF4.8 | 4.80 | 190 | 210 | 230 | 3500 | 600 | 7.20 |
| 1PUF5.8 | 5.80 | 190 | 210 | 230 | 3000 | 600 | 8.70 |
| 1PUF7.0 | 7.00 | 160 | 180 | 200 | 2500 | 600 | 10.50 |
| 1PUF8.0 | 8.00 | 160 | 180 | 200 | 2100 | 600 | 12.00 |
| Mechanical Coupling & Drive Torque Guidelines
| Coupling Parameter | Engineering Specification & Limit |
|---|---|
| Total Input Drive Torque | Total input torque absorbed by the primary front drive shaft equals the sum of both stages: T_total = T1 (2PDF) + T2 (1PUF) ≤ T_max allowable for the selected primary shaft. |
| Primary Shaft Torque Ratings | European 1:8 taper shaft: max 140 Nm; Ø19.05 mm (3/4") cylindrical keyed shaft: max 110 Nm; Involute spline: max 150 Nm. |
| Intermediate Coupling Torque Rating | Hardened internal spline coupling transmits power to rear pump only: T2 (1PUF) ≤ 35 Nm continuous. |
| Common vs. Separated Inlets | Available with separate suction ports for isolated fluid circuits or a unified single large suction port in the intermediate body to minimize external piping. |
| Direct-Fit Replacement & OEM Brand Interchangeability
| Manufacturer Brand | Direct-Fit Drop-In Tandem Series Equivalent |
|---|---|
| CASAPPA | POLARIS Dual Series PLP20 + PLP10 (Group 2 + Group 1 tandem combination) |
| Bosch Rexroth | AZPF + AZPF / AZPF + AZPB Series Group 2 + Group 1 multi-pump combinations |
| MARZOCCHI | 2P + 1P / ALP2 + ALP1 / GHP2 + GHP1 modular tandem gear pumps |
| PARKER Hannifin | PGP511 + PGP505 / PGP517 + PGP502 multiple external gear pumps |
| DANFOSS / Turolla | SNP2NN + SNP1NN Group 2 + Group 1 tandem gear pumps |
| VIVOLO (Vivoil) | XV-2P + XV-1P multiple section external gear pumps |
| SALAMI | 2PB + 1.5PE multiple pump combinations |
Stage 1: Group 2 (2PDF) Technical Data
| Displacement Size (cm³/rev) | Rated Continuous Pressure p1 (bar) | Intermittent Pressure p2 (bar) | Maximum Peak Pressure p3 (bar) | Max. Speed (r/min) | Min. Speed (r/min) | Flow Rate @ 1500 r/min (l/min) | Flow Rate @ 3000 r/min (l/min) |
|---|---|---|---|---|---|---|---|
| 4.0 | 250 | 275 | 300 | 3,500 | 700 | 6.0 | 12.0 |
| 6.0 | 250 | 275 | 300 | 3,500 | 700 | 9.0 | 18.0 |
| 8.5 | 250 | 275 | 300 | 3,500 | 600 | 12.75 | 25.5 |
| 11.0 | 250 | 275 | 300 | 3,500 | 600 | 16.5 | 33.0 |
| 14.0 | 250 | 275 | 300 | 3,500 | 500 | 21.0 | 42.0 |
| 16.5 | 230 | 255 | 280 | 3,000 | 500 | 24.75 | 49.5 |
| 19.5 | 210 | 235 | 260 | 3,000 | 500 | 29.25 | 58.5 |
| 22.5 | 190 | 215 | 240 | 2,800 | 500 | 33.75 | 67.5 |
| 26.0 | 170 | 195 | 220 | 2,500 | 500 | 39.0 | 78.0 |
| 30.0 | 160 | 180 | 200 | 2,500 | 500 | 45.0 | 90.0 |
Stage 2: Group 1 (1PUF) Technical Data
| Displacement Size (cm³/rev) | Rated Continuous Pressure p1 (bar) | Intermittent Pressure p2 (bar) | Maximum Peak Pressure p3 (bar) | Max. Speed (r/min) | Min. Speed (r/min) | Flow Rate @ 1500 r/min (l/min) | Flow Rate @ 3000 r/min (l/min) |
|---|---|---|---|---|---|---|---|
| 0.8 | 250 | 275 | 300 | 4,000 | 800 | 1.20 | 2.40 |
| 1.2 | 250 | 275 | 300 | 4,000 | 800 | 1.80 | 3.60 |
| 1.6 | 250 | 275 | 300 | 4,000 | 800 | 2.40 | 4.80 |
| 2.0 | 250 | 275 | 300 | 4,000 | 700 | 3.00 | 6.00 |
| 2.5 | 250 | 275 | 300 | 4,000 | 700 | 3.75 | 7.50 |
| 3.2 | 250 | 275 | 300 | 3,800 | 700 | 4.80 | 9.60 |
| 4.2 | 240 | 265 | 290 | 3,500 | 600 | 6.30 | 12.60 |
| 5.0 | 220 | 245 | 270 | 3,500 | 600 | 7.50 | 15.00 |
| 6.0 | 200 | 225 | 250 | 3,000 | 600 | 9.00 | 18.00 |
| 7.0 | 180 | 205 | 230 | 2,800 | 600 | 10.50 | 21.00 |
| 8.0 | 160 | 185 | 210 | 2,500 | 600 | 12.00 | 24.00 |
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