描述

Rexroth A4VG28 A4VG40 A4VG56 A4VG71 A4VG90 A4VG125 A4VG180 Axial Piston Variable Hydraulic Pump Cast Iron 350 Bar

Key Entities & Naming Breakdown
A4VG = Series identifier (A4 = high‑pressure axial piston, V = variable displacement, G = large bearings for high loads). The number after indicates displacement in cc/rev – available in 28, 40, 56, 71, 90, 125, and 180. Control variants include DA (hydrostatic speed‑related), EP (electric proportional), and HD (hydraulic remote). Unlike open‑circuit pumps, the A4VG works in a closed loop with an integrated charge pump that replenishes fluid, cools the system, and provides control pressure – a design that alone cuts energy loss by up to 50% compared to open‑loop equivalents.

How the A4VG Works – Inside the Closed Circuit
The Swashplate Principle – Inside the cast‑iron housing, a rotating group of nine pistons bears against a movable swashplate. Increasing the swashplate angle lengthens piston stroke, raising displacement from zero up to the rated cc/rev. Tilt the plate the opposite way, and flow reverses – giving instant forward/neutral/reverse without directional valves.
The Closed‑Loop Advantage – In an open circuit, the pump draws from a tank and returns fluid to the tank. In the A4VG closed circuit, pump outlet connects directly to a hydraulic motor, and motor return goes straight to pump inlet. The built‑in charge pump maintains ~20‑25 bar of supercharge pressure, compensating for leakage and boosting system stiffness. Real‑world example: on a tandem vibratory roller, the A4VG90 drives the traction motor. Push the joystick forward – the swashplate tilts, sending flow to the motor. To brake, the plate crosses zero, reversing flow – no service brakes needed. This closed‑loop architecture delivers 50% faster response and significantly less heat generation than open‑circuit designs.

Common Applications
With robust bearings and peak pressures up to 450 bar (350 bar continuous), the A4VG series is found in: wheel loaders (small to mid‑size) for hydrostatic fan drives or traction; tracked excavators – one pump per track for skid steering; agricultural tractors in CVT transmissions; paving equipment (pavers and compactors); and marine winch drives for closed‑loop winch control. The cast‑iron body ensures durability under extreme duty cycles.

Full Range with Genuine Material Numbers
For procurement, always reference the full model code. Representative material numbers are:

• A4VG28 – typical code AA4VG28HD3DT1/32R‑NSC60F045S, material R902232680

• A4VG40 – AA4VG40EP4D1/32R‑NSC52F096DP, material R902232745

• A4VG56 – A4VG56EP4D1/32R‑NZC02F003BP, material R902232542

• A4VG71 – A4VG71HD3DMT1/32R‑NSF02F041B‑S, material R902205501

• A4VG90 – A4VG90EP4DM1/32L‑NSF02F001PP, material R902148472

• A4VG125 – A4VG125EP4D1/32L‑NSF02F001DP, material R902148748

• A4VG180 – A4VG180HD3DM1/32R‑NZD02F691P‑S, material R902205948

Control Options – DA, EP, HD Explained
DA Control (hydrostatic, speed‑related) – uses engine RPM to control the swashplate, common in mobile machines where the throttle lever doubles as speed control.
EP Control (electric proportional) – a proportional solenoid directly moves the swashplate, ideal for joystick‑controlled vehicles (telehandlers, AGVs).
HD Control (hydraulic, manually remote) – hydraulic pilot pressure from a separate valve, best for simple, low‑cost applications where electronics are not desired.

The 50% Differentiation – Why Choose A4VG
Beyond the closed‑circuit efficiency, the A4VG offers a through‑drive capability – you can mount a secondary gear pump or another axial piston pump directly onto the rear, creating a multi‑pump stack without an extra PTO. This saves space, weight, and installation cost, giving a 50% packaging advantage over single‑pump layouts. Combine that with faster response, cooler oil, and the rugged cast‑iron construction rated at 350 bar, and the A4VG delivers a clear performance edge – exactly what you need for demanding mobile and industrial hydrostatic drives.