Bosch Rexroth A4VG140 closed-circuit variable hydraulic pump

The A4VG140 is a swashplate-type axial piston pump designed for closed-circuit hydrostatic transmissions. In plain terms, it converts an engine's rotating mechanical power into variable, bidirectional hydraulic flow — flow that then drives a matching hydraulic motor to propel a vehicle or machine.

The "140" in the model designation refers to its displacement, roughly 140 cm³ per revolution at maximum swivel angle. This places it in the mid-to-large displacement range of the A4VG series, which spans from small units around 28 cm³ up to large-frame pumps exceeding 250 cm³.

How the A4VG140 Fits Into a Hydrostatic Drive System

A hydrostatic transmission built around the A4VG140 typically pairs it with an A6VM or A2FM-series bent-axis motor.

The Basic Circuit

1. The diesel or electric prime mover spins the A4VG140's input shaft.

2. The swashplate angle, set by the control system, determines oil flow direction and volume.

3. High-pressure oil travels through the closed loop to the drive motor.

4. The motor converts hydraulic energy back into rotational torque at the wheels, tracks, or winch.

5. Return oil flows straight back to the pump's low-pressure side, with the charge pump topping off losses.

Common Control Options

HW (hydraulic, manual) — simple joystick-proportional control, common on smaller machines.

DA (electric proportional) — solenoid-actuated, allowing ECUs to manage swashplate angle for smoother, programmable response.

EP (electric proportional with feedback) — adds a position sensor for closed-loop precision, often paired with CAN bus communication.

Typical Applications

Wheel Loaders — Mid-size loaders (15–20 ton class) often use a single A4VG140 with a bent-axis motor driving both axles through a transfer case, giving stepless speed control and strong low-speed torque.

Excavators — Tracked excavators (20–30 ton) may use two A4VG-series pumps dedicated to travel, giving independent left/right track control for precise steering on slopes.

Agricultural and Forestry Machinery — Harvesters and forwarders use the A4VG140 for ground drive, where instant reversing and smooth speed modulation under variable load matter on soft terrain.

Industrial Winch and Marine Drives — Native bidirectional flow makes it a fit for winch drives and shipboard hydrostatic propulsion.

Maintenance and Troubleshooting

Common Failure Modes

Charge pressure loss — worn charge pump, clogged suction strainer, or failing relief valve; symptoms include sluggish response and overheating.

Swashplate control drift — degraded position sensor or solenoid coil on EP units causes erratic speed changes.

Rising case drain flow/heat — usually points to worn piston shoes or barrel wear, especially past 8,000–10,000 hours in dusty environments.

Cavitation damage — insufficient charge flow at high speed pits pistons and valve plates; often a system design issue, not a component defect.

Practical Tips

Track case drain temperature and flow as a leading health indicator.

Match oil viscosity and cleanliness class to spec — contamination is the top wear driver.

Match control type and shaft spline count, not just displacement, when replacing a unit.

Confirm case pressure limits before sustained high-speed operation in retrofits.

For more information on the A4VG140 hydraulic pump, please visit https://www.baolilaihydraulic.com/product/.

Specifications

Selection Table

Q1: What machines commonly use the A4VG140?

A1: Mid-to-large wheel loaders, excavators (track drive), forestry harvesters/forwarders, and some industrial or marine drives.

Q2: What's the most common cause of premature failure?

A2: Contaminated hydraulic fluid, followed by chronic charge-pressure deficiencies leading to cavitation.

Q3:How to purchase an A4VG140 hydraulic pump?

A3:You can visit https://www.baolilaihydraulic.com/contact/ to contact us and purchase our products through various methods.

Q4:What is the price and delivery time of the A4VG140 hydraulic pump?

A4:The specific price and delivery time will be provided based on the specific model you provide.