Sauer danfoss 51D060 closed circuit bent axis hydraulic motor

The 51D060 is a variable-displacement, bent-axis piston motor from Danfoss's Series 51 (and closely related Series 51-1) product family — a design that traces its lineage back through Sauer-Sundstrand and Sundstrand before the Danfoss acquisition. The "D" in the model code refers to a specific flange/shaft configuration, and "060" identifies the frame size, corresponding to a maximum displacement in the 60 cm³/rev class.

How the 51D060 Fits Into a Closed Circuit System

A closed hydraulic circuit is a loop: fluid flows from the pump, through the motor, and back to the pump's inlet, rather than returning to an open reservoir after every pass. This matters for a few practical reasons.

First, it lets the system reverse direction smoothly, since the pump simply changes its own displacement angle to reverse flow — no directional valve is needed the way it would be in an open circuit. Second, it's more compact and efficient for propel systems because the loop stays largely self-contained. The trade-off is that closed loops need a charge pump to keep the low-pressure side topped up, and they need that flushing function mentioned above, since the fluid isn't constantly refreshed from a large open tank.

In a typical hydrostatic transmission built around the 51D060:

1. A variable displacement axial piston pump (often Series 90) generates flow proportional to its swash plate angle.

2. That flow drives the 51D060's rotating group, producing shaft torque and speed.

3. The motor's own displacement control adjusts its swept volume in response to load or an operator command, shifting the torque/speed balance.

4. A small charge pump maintains loop pressure and makes up for internal leakage.

5. The integral flushing valve continuously bleeds a portion of low-pressure fluid to the case drain for cooling, replaced by cool, filtered charge fluid.

Selecting and Specifying a 51D060

If you're specifying or replacing one of these motors, a few things matter more than the base frame size:

Control type — HP, EP, EQ, N1, N2, HZ, and pressure-compensated variants are not interchangeable without matching the machine's hydraulic and electrical control architecture.

Shaft and flange configuration — SAE, cartridge, or DIN mounting options exist, and the "D" designation itself refers to a particular flange family, so confirm the full model code, not just the frame size.

Displacement limiter settings — minimum and maximum displacement stops are often factory-set for a specific application; matching these matters for correct torque/speed behavior after a rebuild.

Fluid cleanliness — Danfoss publishes an ISO cleanliness target (commonly cited around ISO 18/13 or better) for these units; contamination is one of the leading causes of premature rotating-group wear.

Case pressure limits — running case pressure outside the rated window, even briefly beyond cold-start allowances, risks seal damage and external leakage.

For more information on the 51D060 hydraulic motor, please visit https://www.baolilaihydraulic.com/product/.

Specifications

Selection Table

Q1: Why does the motor start at maximum displacement?

A1: Starting at maximum displacement provides the highest available torque per unit of pump flow, which is what you need to move a stationary loadinto motion —a loaded track, a tensioned winch line, or a stalled wheel. As speed builds and load drops, the control destrokes the motor toward minimum displacement to trade torque for speed.

Q2: What fluid cleanliness does a Series 51 motor need?

A2: Danfoss's technical literature for this motor family typically specifies an ISO cleanliness code in the 18/13 range or better. Since these are high-pressure piston motors with tight internal clearances, contamination control is one of the biggest levers over service life.

Is the 51D060 rebuildable, or should it be replaced? Both op

Q3: What is the price and delivery time of the 51D060 hydraulic motor?

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

Q4:How to purchase a 51D060 hydraulic motor?

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