What Are The Rexroth Gear Pumps?

In the world of hydraulic systems, you'll often hear phrases like "fixed displacement", "high pressure gear units", or "low-noise variable speed drives" thrown around. But when it comes to trusted names in the game, one brand stands out: Bosch Rexroth. And when we drill down to one of their key component lines-the gear pumps-it's worth asking: what exactly are Rexroth gear pumps?

This article will serve as your guide. We will reveal the inner workings of these pumps, introduce the pumps offered by Rexroth, how to interpret their specification sheets, and how, as a hydraulic equipment purchaser, OEM manufacturer, or maintenance engineer, you can make informed decisions when you see Rexroth gear pump product information.

What Is a Gear Pump & The Rexroth Gear Pump Line

Gear Pumps - the Basics

At its simplest, a gear pump is a positive‐displacement pump that uses the meshing of gears to move fluid. Each rotation delivers a fixed volume of fluid - meaning every turn of the gears pushes the same amount of oil (or hydraulic fluid) through. 
Here's a more accessible breakdown:

• As the gears rotate, they separate at the inlet side, creating a vacuum that draws fluid in. 
• The fluid is carried around the outside of the gear pair within the casing.
• As the gears mesh again at the outlet, the volume shrinks and the fluid is forced out under pressure. 

Because of this mechanism:

• Flow is directly proportional to displacement × rpm (i.e., how much the gears move × how fast they turn).
• These pumps are known for robustness and relatively simple design (fewer moving parts than many variable-displacement types).

External vs Internal Gear Pumps

External Gear Pumps

Two external (identical) spur gears mesh side by side; one driven, the other idler. 

They have tighter clearances and typically higher pressure capability, making them good for hydraulic systems where pressure and reliability matter. 

Generally simpler in design, cost-effective, but less flexible in handling ultra‐high viscosity fluids or extreme speed ranges.

Internal Gear Pumps

A larger outer gear and a smaller inner (or idler) gear mesh - "gear within a gear" layout.

They tend to offer smoother flow, lower pulsation and can handle broader viscosity or variable speed ranges. 

They also may accommodate more demanding fluid conditions (higher viscosity or need for low noise) but often at greater complexity or cost.
The Rexroth Gear Pump Line - What They Offer

Rexroth (via Bosch Rexroth) offers both external and internal gear pump ranges within its broader hydraulic-pump portfolio:

• On their site, Rexroth lists "External gear pumps" in the context of converting mechanical energy to hydraulic energy (flow + pressure) with high precision manufacturing to reduce heat losses.
• Their "Internal gear pumps" are described as delivering "demand-oriented volume flows with high efficiency over a wide speed range … low-noise alternative" to variable displacement systems. 
• Specific model lines include the external range (Platform B, F, N, G) and internal gear models like PGF/PGH that support broad speed and viscosity ranges.

Technical Features & Specifications of Rexroth Gear Pumps

Displacement Ranges

One of the first things to check when picking a gear pump is how much fluid per revolution (i.e., displacement) it produces. For Rexroth external gear pumps:

For example, the Series B external gear pumps cover geometric displacements from 1.0 cm³/rev up to about 7.1 cm³/rev for the smallest sizes. 

In larger platforms (Series G, etc) Rexroth offers displacements of 22.5 cm³/rev up to around 100 cm³/rev. 

A key point: bigger displacement = more flow for a given rpm - but also more torque required, more heat potential, potentially larger size.

Pressure Ratings (Continuous, Intermittent, Peak)

Specs that often scare or confuse people: how much pressure can the pump actually handle?

Rexroth's external gear pump "High Performance" line (AZPG) gives continuous pressure up to ~250 bar and intermittent up to ~280 bar in certain sizes. 

For smaller displacements the higher pressure is possible; larger displacement often means a lower maximum pressure. For instance, the technical data shows that size "22…" (small) supports up to 280 bar. 

It is important to recognise: "nominal rating" vs "intermittent/peak rating" vs "system safety margin". A pump rated 250 bar continuous doesn't mean you should routinely operate at 300 bar and expect long life.

Construction & Design Details: What Makes Rexroth Stand Out

Here's where things get a little more "engineering-fun" (if you like that kind of thing):

Rexroth external gear pumps use slide bearings (not simply ball or plain bearings) for high-loading capability and good performance at low speeds. 

The gear wheels in one series have 12 teeth - this is a deliberate design choice to minimise flow pulsation and noise emission. 

The internal sealing (i.e., between gear teeth, housing, bearings) is achieved by pressure-dependent gap sealing - meaning that as delivery pressure increases, clearances are dynamically compensated, improving efficiency and reduced leakage. 

The drive shaft/flange/porting are highly configurable - Rexroth offers multiple shaft types (splined, tapered, keyed), flanges (ISO, SAE), multiple-pump combinations (stacked gear pumps) etc. 

Efficiency is emphasised: These gear pumps are "designed for high efficiency in order to reduce heat losses". 

Customisation & Configuration Flexibility

Because no two hydraulic systems are exactly alike, Rexroth offers lots of variants:

• Different frame/platform sizes (B, F, N, G) which correspond to different displacement/flow ranges. 
• Variation in front covers, flanges, shafts, direction of rotation (clockwise/counter-clockwise). 
• Multiple‐pump combinations (for example stacking two or more pumps on one drive shaft) possible in many models. 
• Versions for low‐noise ("Silence", "Silence PLUS") flagged in specifications.

Noise & Pulsation Characteristics

Often overlooked in pump selection, but very important for system design (especially if your machine runs in quiet environment or variable speed):

The gear design (e.g., 12 teeth as noted above) helps reduce pulsation of flow and noise. 

Rexroth states that their internal gear pumps provide "low-noise alternative … variable-speed drives … wide speed range" in their product portfolio. 

For mobile or machine tool applications where noise matters, selecting a "Silence" variant or a suitable internal gear version might be worthwhile.

How to Select the Right Rexroth Gear Pump (or Replacement)

Choosing the right gear pump is like picking the perfect pair of shoes: it needs to fit your system comfortably, perform without limping, and last longer than your next pair. Let's walk through how to select the right Rexroth gear pump (or a compatible replacement) with both precision and practicality.

Flow Requirement: Matching Displacement to System Demand

Calculate how much flow your system needs: Flow (L/min or gpm) = Displacement (cc/rev or in³/rev) × RPM.

If a pump's displacement is too low, your actuator will struggle or move slowly; too high, and you might overload the drive motor or waste energy. Guidance suggests matching old pump GPM at given RPM when replacing. 

Practical tip: Use the pump's spec sheet-see for example Rexroth's displacement tables-to pick a size that just meets or slightly exceeds your flow at nominal rpm.

Pressure Requirement: Continuous, Intermittent & Peak Loads

Know your system pressure: What is the continuous operating pressure? What about intermittent or peak spikes?

Gear pumps must be rated to handle not just the steady load but any peaks you expect. Many guides emphasise this selection step. 

For Rexroth pumps, make sure you check the series rating (e.g., external gear pump series rated up to ~250-300 bar) and ensure your application doesn't exceed it.

Speed & Fluid Viscosity: Driving Conditions Matter

High RPM means higher stress: The pump's bearings, clearances, and gear meshing must support your speed.

Fluid viscosity impacts performance: Too thin or too thick fluid can change the flow, leakage internally and efficiency. Gear pump selection guides stress matching viscosity. 

Optional tip: If your system uses varying speeds (variable drive), consider a low-noise or wide-speed variant (Rexroth internal gear type) to better accommodate changing conditions.

Mechanical Fit: Mounting, Shaft, Ports, Direction

Flange and shaft type: Does your system drive via keyed shaft, splined, tapered, SAE or ISO flange? 

Porting and direction: Inlet/outlet port sizes, orientation, and whether the pump rotates clockwise (CW) or counter-clockwise (CCW) must match or adapt with minimal rework.

If using a replacement (including OEM/compatible unit), material, mounting footprint, bolt-hole pattern, shaft length all matter for compatibility.

Environment & Application Context: Noise, Pulsation, Contamination

Noise and pulsation: If your machine is in a quiet environment (e.g., workshop near offices, precision machine tool), you'll want low-pulsation internal gear design or "Silence" variants.

Contamination: Gear pumps are robust, but still sensitive to fluid cleanliness. Many failure cases stem from contamination or cavitation. 

Duty-cycle/temperature: Repeated high loads, wide temperature swings or long duty cycles may demand higher-spec pump or more robust construction.

Typical Applications of the Rexroth Gear Pumps

Industrial Machinery

Many industrial machines rely on fixed‐flow, reliable hydraulic circuits where gear pumps (such as Rexroth's external or internal gear types) are a natural fit. According to Rexroth's own product description, their external gear pumps convert mechanical energy (torque + speed) into hydraulic energy (flow + pressure) with high precision manufacturing to reduce heat loss. 
Examples in this category include:

• Hydraulic power units supplying a line of presses.
• Plastic injection-moulding machines where you need a fixed displacement pump feeding a stable circuit.
• Machine tools where noise/pulsation may matter, and internal gear variant options may be chosen for low-noise.

Mobile & Auxiliary Applications

Although gear pumps might not always be first choice in very high pressure mobile hydraulics (where axial piston pumps dominate), they still find use in mobile and auxiliary circuits. Equipment such as material handling, agricultural machinery or general mobile hydraulics often benefit from simpler gear pump designs.
For example, catalogues note that Rexroth gear pumps are used in mobile machinery such as forklifts or agricultural machines, thanks to their compactness and reliability. 

Applications Requiring Medium Pressure and Steady Flow

Gear pumps are particularly well-suited when the system requires a constant flow rather than highly variable flow, when noise/pulsation must be modest, and when the pressure is in a moderate range. According to one product-focus article, Rexroth external gear pumps are used for the transport of fuels, chemical additives, polymers and other media, supporting medium-to‐high pressures and clean fluids. 
So applications might include: metering systems, hydraulic drives for auxiliary functions, lubrication systems, hydraulic circuits in manufacturing lines.

Conclusion & OEM/Alternative Value Proposition

As you've seen throughout this guide, the gear-pump solutions from Rexroth deliver reliable fixed-displacement performance, wide application suitability (external vs. internal gear designs), and robust specification ranges. But if you're operating or sourcing for specialized hydraulic systems-including replacements, OEM/ODM builds or tailored configurations-here's how Poocca Hydraulic (Shenzhen) Co., Ltd. steps in as your strategic partner.

Recap of Key Points

Rexroth gear pumps work on a positive‐displacement principle: each revolution moves a fixed volume of fluid. They come in external gear and internal gear variants, each suited for different flow-/speed-/noise-/viscosity scenarios.

Key specs to check: displacement (cm³/rev or in³/rev), maximum continuous and intermittent pressure, speed and viscosity capability, mechanical fit (shaft, flange, porting) and noise/pulsation characteristics.

In actual applications, gear pumps are ideal in circuits needing steady flow, moderate pressure and compact design-such as industrial machinery, auxiliary hydraulics and systems where cost-effectiveness matters.

Poocca's Value to You

From the perspective of Poocca's gear-pump business, here are the differentiators and how it adds value to your procurement, OEM or replacement strategy:

Compatibility with Rexroth Specs: Poocca offers gear pumps compatible with Rexroth's spec ranges (for example external gear pumps like AZPF up to ~280 bar) and other recognised brands.

Customization & OEM/ODM Capability: Whether you need modified flange/shaft configurations, special porting, multi-pump assemblies, tailored mounting or branding (your logo), Poocca provides flexible OEM/ODM services.

Agility & Cost-Effectiveness: With its manufacturing footprint (20+ years in hydraulics), stocked models, and streamlined lead times, Poocca can often serve faster or more cost-effectively than generic replacements. 

Holistic Hydraulic Partner: Beyond gear pumps, Poocca's product range spans gear pumps, piston pumps, vane pumps, hydraulic motors, valves and accessories. This makes them suitable as a one-stop partner for system integrators, OEMs or after-market suppliers.