Rexroth A4VTG71 & A4VTG90 Concrete Mixer Hydraulic Piston Pump

The A4VTG71 and A4VTG90 (collectively known as the A4VTG platform) series high-performance swashplate axial piston variable displacement pumps manufactured by LIC Hydraulic (comprehensively matching strict engineering nomenclature including A4VTG71HWCSD32L-NLD10F001S-S, A4VTG71HW, and A4VTG90HW) are heavy-duty core fluid power units custom-engineered for closed-circuit loops driving transit concrete mixer drums. Conforming precisely to standard industrial SAE mounting pilots, input drive shafts, integrated charge pump dimensions, control valving response metrics, and closed-loop hydraulic performance graphs, this entire pump line delivers 100% drop-in interchangeability with Bosch Rexroth A4VTG series concrete mixer dedicated pumps.

Transit mixers operate under severe site conditions characterized by billowing dust, rough off-road twisting, and continuous high-frequency drum rotation reversals. Substandard aftermarket pumps frequently suffer from piston shoe lift-off, unstable charge pressure profiles, or erratic pilot servo feedback which compromises machine stability. LIC solves these operational failure modes by performing complete material and metallurgical geometry upgrades across the entire internal rotating group, alongside integrating a high-efficiency gerotor charge pump and dual high-pressure relief networks. Every single A4VTG pump undergoes 100% full-load simulated transit mixer concrete holding, sudden reversal, and field shaking operational factory testing prior to shipment. Maintaining high volumetric efficiency up to a 400 bar intermittent peak pressure threshold, our pumps deliver a premium, long-life solution for B2B global equipment distributors, concrete fleet mechanics, and machinery integrators.

Technical Specifications

Accurate, catalog-verified engineering data for the A4VTG71 / A4VTG90 Series 32 configuration:

• Product Series: A4VTG Series Swashplate Axial Piston Variable Displacement Closed-Loop Pump Line

• Displacement Framework Platforms:

  • A4VTG71: Nominal displacement of 71.0 cm³/rev (4.33 ci/rev)

  • A4VTG90: Nominal displacement of 90.0 cm³/rev (5.49 ci/rev)

• Full Structural Model Code Breakdown Example (A4VTG71HWCSD32L-NLD10F001S-S):

  • A4VTG71: 71.0 cm³/rev closed-loop volumetric configuration sizing.

  • HW: Proportional manual hydraulic servo control mechanism (Hydraulic Servo Control) with mechanical feedback linkage, providing exceptional micro-positioning smoothness.

  • CS: Integrated Pressure Cut-Off (Pressure Cut-Off) protection valve safeguarding the high-pressure loop.

  • D32: Product design structural series index index 32 (perfect match for mainstream current fleet standards).

  • L: Counter-Clockwise (CCW) rotation orientation evaluated looking directly onto the shaft end.

  • NLD10F001S-S: Integrated onboard standard-capacity charge pump, standard SAE rear flange mating interfaces, pre-machined speed sensor ports, and high-torque splined drive shaft.

• Nominal Continuous Operating Pressure Limit: 350 bar (35 MPa / 5075 psi)

• Intermittent Maximum Peak Pressure: 400 bar (40 MPa / 5800 psi)

• Integrated Charge Pump Pressure Setting: Maintained between 20 bar – 25 bar automatically.

• Maximum Rated Rotational Speed Limit: A4VTG71 up to 3300 rpm; A4VTG90 up to 3050 rpm.

• Swashplate Response Window: 0.2 to 0.5 seconds for complete cross-center reversal without pressure spikes.

• Housing Block Shell Construction: High-density heavy ductile iron compression-resistant shroud. Net mass weight: A4VTG71 approx. 50.0 kg; A4VTG90 approx. 65.0 kg.

Key Technical Advantages

• Precision Manual Hydraulic HW Proportional Control Block: Incorporates a premium pilot hydraulic servo amplifier coupled with a mechanical position feedback bar. When the operator adjusts the cab control cable/lever, the valve translates the displacement smoothly into dual large-bore stroke servo pistons. This dampens cross-center direction shifts, preventing hydraulic water hammer shocks and isolating the drum gearbox from sudden inertial spikes.

• Fully Packaged Closed-Circuit Safeguard Architecture: The internal block integrates all necessary valves for closed-loop operation: two high-pressure cross-port safety relief valves linked with a pressure cut-off regulator (CS), and a low-pressure charge boost overflow valve. If the mixer drum jams due to hardening concrete aggregates, the valve network opens within milliseconds to vent excess pressure, instantly saving the pump and motor from destruction.

• Sintered Bi-Metal Cylinder Block & Hydrostatically Balanced Pistons: The internal cylinder bores are layered via dual-metal copper alloy sintering techniques, matched with mirror-finished, hardened steel pistons. A rigid hydrostatic oil film cushion balances the slipper shoes against the swashplate face. This prevents boundary contact scuffing and slipper detachment, even when hauling maximum tonnage over steep, unpaved construction grades.

• Rigid Tapered Shaft Bearing Layout and High-Volume Charge Support: The central drive shaft is supported at both ends by high-load tapered roller bearings capable of countering engine-side torsional harmonics. The rear-integrated gerotor boost charge pump features expanded volumetric efficiency, maintaining sufficient loop cooling fluid exchange and pilot servo command control pressures even when the truck engine is idling.

Application Areas

The A4VTG71 and A4VTG90 closed-circuit variable displacement piston hydraulic pumps provide modular compact configurations, extreme peak pressure handling, and absolute direction management across global mixing assets:

• Commercial Transit Concrete Mixer Trucks: Main high-pressure hydraulic drive powering rotating drums across 6 m³, 8 m³, 10 m³, 12 m³, and 14 m³ commercial aggregate transport trucks.

• Self-Loading Cross-Country Mobile Mixers: Hydrostatic drive systems inside rough-terrain utility vehicles equipped with integrated automated front loading bucking and blending systems.

• Stabilized Soil & Industrial Slurry Blending Stations: Driving stationary heavy-duty continuously variable ribbon blenders and large-scale manufacturing mortar plants.

Expert Maintenance Tips

• Mandatory Dual Housing and Servo Control Pre-Priming: Lubrication inside a closed-loop pump configuration is critical. Before starting up a newly installed or newly rebuilt unit (such as A4VTG71HWCSD32L-NLD10F001S-S), fill the pump housing completely with clean anti-wear hydraulic fluid via the top case drain port T, and pre-prime the HW servo valve block cavity. Let the truck engine idle without load for 10 minutes; never actuate the cab drum control lever immediately upon cold ignition.

• Perform Rigorous Charge Pressure Inspections via Port G: Boost charge pressure is the life-support system of a closed loop. If charge pressure slips under 16 bar, the main piston shoes lose contact with the swashplate during the intake cycle, triggering destructive physical impacts. Connect a pressure gauge to testing Port G regularly; if a pressure drop is observed, inspect and replace the charge suction filter elements immediately.

• Execute Stringent Loop Flushing Standards to Protect the Closed Circuit: Fluid inside a closed circuit circulates repeatedly between pump and motor without dropping back to the main tank. Debris from a worn component will cause catastrophic loop damage if left unchecked. Before linking a replacement pump to old lines, perform a thorough system-wide dynamic flush, clean out the motor core, and replace all filter elements. Maintain a fluid benchmark of ISO 4406 18/16/13 or better.