Rexroth A4VG closed circuit hydraulic pump for Doppstadt Shredder DW3060 DT52 93257664021 93257664022

The A4VG is a variable displacement axial piston pump built by Bosch Rexroth, one of the most established names in industrial and mobile hydraulics. It's designed specifically for closed-circuit hydrostatic transmissions — the kind of system where hydraulic fluid flows in a continuous loop between the pump and a matching hydraulic motor, rather than drawing fresh oil from a tank on every cycle.

How the A4VG Powers a Doppstadt Shredder's Drivetrain

In a typical Doppstadt configuration, the diesel engine drives the A4VG pump directly off the flywheel housing or through a splitter gearbox. The pump then sends high-pressure oil to an A6VM or A2FM series Rexroth motor mounted on the shredder rotor shaft.

Example — AK 435 Doppstadt shredder: The engine turns the A4VG180 at rated speed. As the operator feeds material into the hopper, the shredder's control electronics sense rotor load through pressure transducers and command the pump's swash plate angle in real time — reducing displacement when the rotor bogs down, and restoring full flow once the load clears. This closed-loop torque control is what lets the machine keep chewing through a mixed load of stumps and pallets without stalling every few seconds.

Example — DW 3060 mobile shredder: Here, the A4VG works in tandem with a second open-circuit pump group for auxiliary functions (conveyor, magnet, screen deck), while the closed-circuit A4VG is dedicated purely to rotor drive — illustrating how Doppstadt separates primary shredding torque from secondary functions to protect the main drive from unrelated hydraulic demands.

Common Failure Signs and Root Causes

Because the A4VG sits under constant high pressure and thermal cycling, it's one of the first components to show wear when a shredder is overworked or under-maintained.

Symptoms Operators Report

1. The rotor loses power under load, even though the engine RPM stays normal

2. Whining or knocking noise from the pump housing, especially at startup

3. Overheating hydraulic oil, sometimes accompanied by a burnt smell

4. Slow or delayed rotor reversal when clearing jams

5. Metal particles or fine debris in the return filter

Underlying Causes

1. Charge pressure loss — a worn charge pump or clogged charge filter starves the main pistons of makeup oil, leading to cavitation and eventual scoring of the cylinder block.

2. Swash plate bearing wear — years of shock loading from jams wear the trunnion bearings, causing displacement control lag.

3. Contaminated fluid — shredders operate in dusty, debris-heavy environments; ingress through breather caps or damaged seals accelerates internal wear far faster than in cleaner applications.

4. Overheating — undersized coolers or clogged heat exchangers push oil past the pump's thermal tolerance, breaking down the fluid's viscosity and lubricating film.

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Q1: What size A4VG pump does my Doppstadt shredder need?

A1: It depends on the model and rotor configuration. Doppstadt's parts documentation or dealer network can confirm the exact frame size (e.g., A4VG71, A4VG125, A4VG180) and control type for your serial number — swapping in an undersized pump will bottleneck torque, while an oversized one wastes engine power and cost.

Q2: Is it normal for the pump to run hot on a shredder?

A2: Some heat rise under continuous high-load shredding is expected, but oil temperatures consistently above 80°C (176°F) at the pump case indicate a cooling or contamination problem that should be investigated before it damages internal components.

Q3:What is the price and delivery time of the A4VG hydraulic pump for the Doppstadt Shredder?

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

Q4:How to purchase an A4VG hydraulic pump for Doppstadt Shredder?

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