6423-081 Eaton ACA Hydraulic Pump 105cc 420 bar

Product Overview

The 6423-081 is an Eaton/Danfoss ACA series heavy-duty variable axial piston pump in the 64 series displacement size (105.4 cm³/rev). The pump features a swashplate variable design with manual control (including neutral lockout switch) and pressure inhibition (setting 414 bar), specifically engineered as the main hydraulic power source for closed-circuit hydrostatic transmission systems in concrete mixer trucks. Its official model code is ACA642330L1B00MDC002M0D030D013A0B.

The ACA series is Eaton’s standard factory power component developed for concrete mixers, underground mining loaders, compact rollers, and other heavy construction machinery. Among the three mainstream sizes (46, 54, 64), the 6423 series has the largest displacement and strongest load capacity, suitable for large mixers and heavy mining transport vehicles. The pump features a high-strength ductile iron housing for greater noise damping and wall strength, a high-strength swashplate resisting deflection under high load, a built-in charge gear pump for continuous oil supply, and a mechanical face seal design tolerating high speed and high case pressures.

The model code ACA642330L1B00MDC002M0D030D013A0B decodes as follows: ACA is the product series (heavy-duty variable pump), 64 is the displacement group (105.4 cm³/rev), 2 indicates variable displacement pump, 3 indicates design series 1 (models 33-64), 30 is the input shaft specification (13-tooth 8/16 pitch spline with extension), L is counter-clockwise rotation, 1 is the valve plate type (impulse ports), B is the main port specification (SAE J518 standard), MD is manual control with neutral lockout switch, C is the control supply orifice (0.044 diameter), 0 is no pressure override, 2 is internal pressure inhibition, M is the pressure inhibition setting (414 bar), D is the charge pump type (external drain port), 3 is the charge pump displacement (21.0 cm³/rev), and D is the charge pressure relief valve setting (15 bar).

Technical Specifications 

• Model: 6423-081

• Official Model Code: ACA642330L1B00MDC002M0D030D013A0B

• Product Series: Eaton/Danfoss ACA heavy-duty variable piston pump

• Pump Type: Swashplate axial piston variable pump

• Displacement: 105.4 cm³/rev (6.431 in³/rev at 18°)

• Nominal Pressure: 420 bar (6,000 psi)

• Peak Pressure: 480 bar (7,000 psi)

• Maximum Speed (18° swashplate): 3,720 rpm

• Output Flow (@3500 psi): 99.1 gpm / 375 lpm (@241 bar)

• Input Torque (@3500 psi): 3,900 lb-in / 441 Nm (@241 bar)

• Input Shaft: 13-tooth 8/16 pitch spline with extension

• Input Rotation: Counter-clockwise (left-hand)

• Control: Manual control with neutral lockout switch (wide-band neutral)

• Pressure Inhibition Setting: 414 bar (6,000 psi), internal

• Charge Pump Displacement: 21.0 cm³/rev (1.28 in³/rev)

• Charge Pressure Relief Valve Setting: 15 bar (220 psi)

• Housing Material: High-strength ductile iron

• Built-in Features: Charge gear pump, high-pressure overload protection, internal servo piston swashplate control

• Mounting: Flange mounting, identical dimensions to original

• Circuit: Closed circuit

• Weight (approx.): Varies by configuration

Key Technical Advantages

1. Swashplate Variable Mechanism with Internal Servo Piston Control

The 6423-081 employs the classic swashplate variable design of the Eaton ACA series, with the swashplate pivot-mounted on tapered roller bearings and controlled by two internal servo pistons. This design enables stepless pump displacement adjustment based on system demand, maintaining constant drum rotation speed whether the truck is traveling down a highway or idling at a traffic light. The high-strength swashplate design resists deflection under high load, ensuring stable displacement control precision at the nominal pressure of 420 bar.

2. Built-in Charge Pump with Closed-Circuit Integration

The pump features a built-in gerotor charge gear pump (displacement 21.0 cm³/rev) that continuously provides charge pressure to the closed circuit, preventing main circuit cavitation and maintaining system oil circulation. The charge pressure relief valve is set at 15 bar, ensuring stable charge pressure. The closed-circuit design enables smooth clockwise and counter-clockwise rotation of the mixing drum without power loss under uphill full loads, with low heat generation during non-stop operation.

3. High-Strength Ductile Iron Housing with Durability

The ACA series pump features a high-strength ductile iron housing, offering greater wall strength and noise damping compared to conventional cast iron. The thick-walled wear-resistant housing design reduces internal leakage during long-hour continuous running, maintaining steady performance on dusty, bumpy construction sites. The mechanical face seal design tolerates high speed and high case pressure conditions, with a cartridge seal design for easy serviceability.

4. Neutral Lockout Control with Pressure Protection

The pump features manual control with a neutral lockout switch (wide-band neutral). The operator can manually switch pump displacement direction to control drum forward/reverse rotation, with the neutral position lockable to prevent unintended rotation. The internal pressure inhibition function is set at 414 bar; when system pressure reaches the setting value, pump displacement is automatically reduced to prevent overload damage. The pump also incorporates a high-pressure overload zero-flow control valve, providing additional safety protection for the system.

Application Areas

• Concrete Mixer Trucks: Mixing drum drive main hydraulic pump, controlling drum forward/reverse rotation and speed

• Underground Mining Equipment: Scooptram and mining carrier travel power

• Road Rollers and Soil Stabilizers: Seamless high/low speed travel drive

• Port Tractors and Heavy Agricultural Machinery: Transmission system refitting

• Tracked Special Vehicles: Heavy equipment power transmission

Expert Maintenance Tips

1. Charge Pressure Inspection: The charge pump provides continuous oil supply to the closed circuit, with the charge pressure relief valve set at 15 bar. Inspect charge pressure every 500 operating hours, ensuring it remains within the set range. Low charge pressure causes main pump cavitation; excessive pressure increases system heat generation.

2. Pressure Inhibition Setting Verification: The internal pressure inhibition setting is 414 bar (6,000 psi). Verify the pressure inhibition function every 1,000 operating hours, confirming the pump reduces displacement normally when reaching the set pressure. If inhibition fails, check the servo piston and control valve spool.

3. Hydraulic Fluid Cleanliness Control: The ACA series pump features precision clearances in the piston and distribution pairs. Maintain hydraulic fluid cleanliness at ISO 18/15 or NAS Level 9 or better. Replace hydraulic fluid and filter elements every 1,000 operating hours or annually, with filter element filtration accuracy no less than 10 μm.

4. Input Shaft Installation Notes: The input shaft is a 13-tooth 8/16 pitch spline. During installation, ensure the spline mating surfaces are free of burrs and damage, with coaxiality deviation not exceeding 0.05 mm. Apply appropriate grease to the spline to prevent corrosion.

5. Restart After Extended Storage: For products stored over 6 months, manually rotate the shaft 2–3 revolutions to confirm free rotation, then run at low pressure under no load for 10 minutes, confirming normal case temperature and leakage before gradually applying load.