Bosch Rexroth A4VTG axial piston pump for the Stetter Engineering Equipment 60102940 60103119 60103434 60103810 60107145 60107146 98375623

The A4VTG is a variable-displacement axial piston pump built by Bosch Rexroth, a division of the Bosch Group and one of the most established names in industrial and mobile hydraulics. It belongs to Rexroth's swashplate family of pumps, purpose-built for closed-circuit hydrostatic drives.

Why Stetter Uses the A4VTG in Its Mixer Trucks

Stetter, part of the Putzmeister/Zoomlion group, is one of Europe's leading manufacturers of truck-mounted concrete mixers and stationary mixing plants. Drum rotation on a concrete mixer isn't a simple on/off task — it needs to run continuously at variable speed for hours, reverse for discharge, and respond instantly to load changes as the concrete's weight and consistency shift during transport.

That combination of requirements is exactly what a closed-circuit axial piston pump is built for.

Matching Pump to Application

1. Continuous duty cycle. A concrete drum turns for the entire haul, not in short bursts. The A4VTG's closed-loop design recirculates fluid efficiently, reducing heat buildup during long agitation cycles.

2. Infinitely variable speed. Drivers need slow agitation during transport and fast rotation for loading and discharge. The swashplate's stepless displacement control delivers that range without gear shifting or clutching.

3. Reversibility for discharge. Because the swashplate itself reverses flow direction, the same pump handles both mixing and pouring without additional valving — fewer components, fewer failure points.

4. Compact packaging. Mixer trucks have limited chassis space between the drum, the engine, and the frame. The A4VTG's frame sizes are chosen to fit that envelope while still meeting torque demand.

5. Durability under vibration and dust. Job sites are unforgiving environments. Rexroth's mobile-hydraulics engineering targets exactly this kind of duty — on-road vibration, temperature swings, and dust ingress.

How the A4VTG Works in a Stetter Drum Drive Circuit

Understanding the pump's role is easier with the full circuit in view.

The Closed-Circuit Hydrostatic Transmission

In a Stetter mixer, the A4VTG pump is coupled — usually via a PTO or auxiliary diesel engine — to draw mechanical power and convert it into hydraulic flow. That flow travels through high-pressure hoses to a hydraulic motor mounted at the drum's drive end. Unlike an open circuit, the return flow doesn't go back to a tank; it flows directly back into the pump's suction side, forming a closed loop between pump and motor.

Boost pump function: because a closed circuit loses a small amount of fluid to internal leakage and case drain, the integrated boost pump continuously tops up the loop and supplies pilot pressure for the swashplate control.

Pressure protection: the twin relief valves guard both the pump and motor from pressure spikes — for example, if the drum suddenly encounters resistance from a stiff, partially set batch of concrete.

Proportional control: the operator's throttle or drum-speed command adjusts the swashplate angle, which changes flow output — and therefore drum speed — smoothly and proportionally.

Common Issues and Maintenance Considerations

Like any high-pressure hydraulic component, the A4VTG rewards proper care and punishes neglect.

Typical Failure Modes

Fluid contamination. Concrete environments are dusty and abrasive; contaminated hydraulic fluid accelerates wear on pistons, cylinder bores, and the swashplate bearing surfaces.

Overheating. Long duty cycles combined with undersized coolers or degraded fluid can push operating temperatures past the pump's rated limits, thinning the oil film and increasing internal wear.

Internal leakage/loss of efficiency. As seals and piston shoes wear, volumetric efficiency drops — drum speed becomes sluggish, especially under load.

Boost pressure faults. A failing charge pump or clogged suction filter starves the main circuit, leading to cavitation noise and erratic control response.

Practical Maintenance Steps

Follow Bosch Rexroth's specified fluid types (per data sheets RE 90220 for mineral oil or RE 90221 for environmentally acceptable fluids) — the A4VTG is explicitly not rated for HFA, HFB, or HFC fire-resistant fluids.

Keep filtration tight; concrete-industry hydraulics are especially vulnerable to particulate contamination.

Monitor case drain flow and temperature as early indicators of internal wear before a full failure occurs.

Source genuine or certified-rebuilt units and OEM seal kits when servicing — mismatched components are a common cause of premature repeat failures on mixer hydraulics.

For more brands and equipment models, please visit https://www.baolilaihydraulic.com/brand/

Q1: Where does the A4VTG fit in a Stetter truck's overall hydraulic system?

A1: It's the primary drive pump for the mixing drum, typically powered off the chassis engine's PTO or a dedicated auxiliary engine, and paired with a hydraulic motor mounted at the drum's rear or front drive end, depending on the truck configuration.

Q2: How do I know if my A4VTG needs servicing?

A2: Watch for slower-than-normal drum rotation, unusual whining or cavitation noise, rising hydraulic fluid temperature, or visible fluid leaks around the shaft seal. Any of these point to internal wear worth inspecting before a full failure.

Q3: What is the price and delivery time of the Rexroth A4VTG pump for the Stetter Engineering Equipment?

A3: The specific price and delivery time will depend on the equipment model or specific product model you provide.

Q4: How do I purchase a Rexroth A4VTG pump for Stetter Engineering Equipment?

A4: Visit https://www.baolilaihydraulic.com/contact/ to contact us and purchase our products through various methods.