Eaton Vickers 3520VQ-25A-8-1BB-20 Double Vane Pump

Eaton Vickers 3520VQ-25A-8-1BB-20 Hydraulic Double Vane Pump

The Eaton Vickers 3520VQ-25A-8-1BB-20 is a fixed-displacement, intra-vane double hydraulic pump engineered specifically for rigorous marine deck machinery, offshore systems, and heavy-duty industrial hydraulic power units (HPUs). Built on the field-proven Vickers VQ platform, this tandem unit integrates two independent cartridge rotating groups driven by a single common input shaft.

The primary shaft-end section (35VQ frame) provides high volumetric displacement, while the secondary cover-end section (20VQ frame) delivers dedicated auxiliary, pilot, or high-pressure secondary fluid flow. Featuring a 10-vane intra-vane rotor design with bimetallic, hydrostatically balanced flexible bronze-faced side plates, the 3520VQ minimizes internal leakage across extreme thermal excursions, drastically suppresses pressure ripple pulsation, and mitigates radial bearing loads via diametrically opposed dual-cam inlet and discharge tracking.

Technical Specifications

Key Features

1. Intra-Vane Pressure-Balanced Cartridges: Incorporates intra-vane technology that routes hydraulic pressure directly underneath the vanes, equalizing tracking force against the elliptical cam ring to prevent premature vane edge washing and excessive internal friction.
2. Bimetallic Bronze/Steel Wear Plates: Features flexible bronze wear plates mechanically backed by structural steel cavities to ensure optimum hydrodynamic clearances and resistance to thermal galling under high-load continuous cycles.
3. Zero Radial Bearing Load Architecture: Opposed dual suction and discharge port zones eliminate radial hydraulic side-loading on the drive shaft and bearings, dramatically extending bearing fatigue life
4. Independent Dual-Circuit Power: Delivers two isolated hydraulic circuits from a single prime mover, permitting split-flow operations (e.g., primary winch control with isolated secondary pilot/brake release) without flow dividers.
5. Drop-In Field Serviceability: Rotating groups utilize modular replacement cartridge assemblies (P/N 02-137233 for 35VQ25 and P/N 02-137222 for 20VQ8), enabling full overhaul or flow alteration without disconnecting system piping or the pump housing.

Applications

• Marine & Offshore Deck Machinery: Mooring winches, anchor windlasses, cargo cranes, constant-tension winches, stern ramp actuators, and secondary steering gear HPUs.
• Plastics & Die Casting Equipment: Injection unit screw drives, core-pull hydraulic systems, and die-clamping circuits.
• Heavy Industrial Automation: High-tonnage hydraulic stamping presses, billet shears, scrap metal balers, and continuous casting systems.
• Mobile Heavy Machinery: Mining excavators, harbor reachstackers, drill rigs, and crawler crane pilot/cooling circuits.

Compatibility

• Eaton Vickers Legacy Units: Replaces older 3520V-25A-8-1BB-20 industrial series pumps (upgrades continuous pressure handling from 172 bar to 207 bar).
• Danfoss / Vickers Replacement Families: 100% envelope-compatible with Danfoss 3520VQ, Denison T6ED series (with port/shaft adaptation), and Parker Denison vane manifolds.
• Direct Prime Mover Adapters: Matches standard IEC 132/160/180 frame bellhousings and NEMA 254TC/256TC electric motor C-face brackets configured for SAE “C” 2-bolt mounts.

Part Number Cross-References & Identifiers

• Manufacturer Part Number (MPN): 3520VQ-25A-8-1BB-20
• Danfoss / Eaton Global Part Code: 02-137350 / 433335 Series
• Shaft-End Cartridge Kit: Eaton 02-137233 (35VQ25A kit)
• Cover-End Cartridge Kit: Eaton 02-137222 (20VQ8 kit)
• Standard Seal Kit (Buna-N): Eaton 02-137301 (F3 Viton Seal Kit: 02-137302)

Frequently Asked Questions

What does the 3520VQ designation mean on an Eaton Vickers pump?

The 3520VQ designates an Eaton Vickers high-pressure double vane pump platform comprising a 35VQ frame size on the shaft end and a 20VQ frame size on the cover end. It provides independent dual-circuit hydraulic flow from a common drive shaft and common suction housing.

Can I run different working pressures on the two discharge ports?

Yes. The shaft-end port (35VQ) and cover-end port (20VQ) are completely isolated after fluid enters through the common suction port. You can run the primary circuit at high pressure (up to 207 bar) and the secondary circuit at lower pilot or auxiliary pressures without cross-port leakage.

What is the difference between standard Vickers V series and VQ series pumps?

Vickers VQ series pumps are engineered with intra-vane technology, hydrostatically balanced bimetallic flexible side plates, and high-tensile cast housings. This design enables higher maximum pressures (207 bar vs. 172 bar on V series), higher RPM ratings, lower audible noise emissions, and resistance to cold-start flow degradation.

How do I reverse the rotation of this pump in the field?

Reversing rotation requires opening the pump, extracting both the 35VQ and 20VQ cartridge kits, flipping the cam rings according to the factory instruction stampings, reversing the internal rotor port plates, and adjusting the port relationships. If field changes are required, use genuine Vickers service tools and seal kits.

Which hydraulic oil viscosity is recommended for marine HPUs using this pump?

An ISO VG 46 or ISO VG 68 premium mineral-based anti-wear hydraulic oil (DIN 51524 Part 2 HLP) is standard for marine deck installations. Optimum operating viscosity is between 13 and 54 cSt, with minimum system filtration held at ISO 4406 cleanliness class 19/17/14.