Sauer danfoss 51D080 bent axis hydraulic motor

If you've spent any time around mobile hydraulics — wheel loaders, forestry equipment, winches, drilling rigs, or marine deck machinery — you've probably run into a Series 51 bent axis motor at some point, even if you didn't know it by name. The Sauer-Danfoss 51D080 is one of the more common displacement sizes in that lineup, and it has a reputation for doing a hard job without much drama.

Key Technical Characteristics of the 51D080

Before specifying or ordering a 51D080, an engineer or technician typically needs to confirm several parameters directly against Danfoss's current technical datasheet, since exact figures can vary by revision, shaft type, and mounting configuration. That said, the general performance envelope of the 80 cc/rev frame size in the Series 51 line includes:

Displacement and Output

Nominal displacement around 80 cm³/rev, giving it a mid-range position in the Series 51 lineup (which spans roughly 20 cc to 250+ cc frame sizes)

Fixed displacement design (Series 51 also offers variable-displacement variants under different model codes)

Continuous and intermittent/peak torque ratings that scale with system pressure

Pressure Capability

Rated continuous pressure typically in the 350–420 bar range

Peak/intermittent pressure capability often reaching 450–480 bar, which is a major differentiator versus lower-cost gerotor or vane motors

Speed Range

Capable of both low-speed, high-torque operation and higher-speed running, making it flexible across direct-drive and geared applications

Mounting and Shaft Options

Multiple SAE-style mounting flange options

Splined, keyed, or tapered shaft variants, depending on the application

Multiple port configurations (SAE flange ports, threaded ports) depending on regional and OEM requirements

Housing and Seals

Robust cast housing designed for contamination resistance and shock loading

Shaft seal options rated for varying case pressure and environmental exposure

A word of caution: displacement and pressure numbers on any hydraulic motor are configuration-dependent. Always cross-reference the specific part number and revision against Danfoss's official technical information sheet before finalizing a system design — a few bars or cc of difference can change pump sizing, relief valve settings, and duty cycle assumptions.

Installation and System Design Considerations

Matching the Motor to the Pump

Displacement, not just pressure rating, drives speed and torque output. An 80 cc/rev motor paired with an oversized pump will run faster than intended unless flow is metered — always calculate expected output speed using the formula:

Motor speed (rpm) = (Pump flow in L/min × 1000) / Displacement (cc/rev)

Case Drain and Contamination Control

Bent-axis motors are sensitive to contamination at the piston-to-shaft interface. A properly sized case drain line, along with filtration meeting the manufacturer's cleanliness class recommendation, meaningfully extends service life.

Mounting Alignment

Because the shaft and housing tolerances on bent axis motors are tight, misalignment during installation — especially with direct-coupled loads — is a common early failure cause. Flexible couplings or precise flange alignment are worth the extra installation time.

Thermal Management

High-pressure operation generates heat. Systems running the 51D080 near its upper pressure range should budget for adequate cooling capacity in the hydraulic circuit, particularly in continuous-duty applications.

Common Troubleshooting Scenarios

Reduced torque output: Often traces back to internal wear (leakage across pistons), incorrect relief valve setting, or a pump not delivering rated pressure.

Excessive case drain flow: A strong early indicator of internal seal or piston wear — worth monitoring over time rather than reacting to a single reading.

Overheating: Usually a symptom of running near continuous peak pressure without adequate cooling, or a restriction somewhere in the return/case drain path.

Unusual noise or vibration: Frequently a coupling alignment issue rather than a motor defect — check alignment before assuming internal failure.

For more information on the 51D080 hydraulic motor, please visit https://www.baolilaihydraulic.com/product/.

Specifications

Selection Table

Q1: What's the difference between a bent-axis motor and a standard axial piston motor?

A1: In a bent-axis motor, the entire cylinder block tilts relative to the drive shaft. In a swashplate axial piston motor, the cylinder block stays aligned with the shaft while an angled plate drives the pistons. Bent axis designs generally tolerate higher pressure and offer better power density, at a higher manufacturing cost.

Q2: How do I know if my 51D080 needs rebuilding versus replacement?

A2: A gradual rise in case drain flow, a drop in output torque at rated pressure, or increased internal noise are the usual early indicators. A qualified hydraulics shop can pressure-test and tear down the unit to assess piston, valve plate, and seal wear before deciding between rebuild and replacement.

Q3: What is the price and delivery time of the 51D080 hydraulic motor?

A3: The specific price and delivery time will be provided based on the specific model you provide.

Q4:How to purchase a 51D080 hydraulic motor?

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