Sauer danfoss 90M075 axial piston hydraulic motor

The 90M075 is a fixed-displacement, in-line axial piston motor built for closed-circuit hydrostatic transmissions (HST). "90" identifies the Series 90 platform, "M" denotes a motor (as opposed to "R" for pump), and "075" is shorthand for its 75 cm³ per revolution displacement.

Inside the housing, a cylinder block carrying nine pistons rotates against a fixed swashplate. Pressurized oil entering through one working port pushes the pistons against the swashplate angle, converting hydraulic pressure into rotating shaft torque. Because the swashplate is fixed rather than variable, the 90M075 delivers a constant relationship between flow in and speed out — simple, robust, and predictable.

How the 90M075 Fits Into a Hydrostatic System

A Series 90 motor rarely works alone. In a typical hydrostatic transmission, a variable-displacement Series 90 pump — driven by the engine — feeds the fixed-displacement 90M075 motor in a closed loop. The pump's swashplate angle controls flow, which in turn controls motor speed; reversing the pump's swashplate reverses the loop's flow direction and the motor's rotation.

An integrated charge pump on the primary pump replenishes losses and provides cooling flow; the motor's case drain carries away internal leakage and any loop-flushing flow, which is why proper case pressure limits and a correctly sized reservoir matter so much for motor longevity.

Typical Applications

Excavator swing drives — precise, reversible rotary motion for the upper structure

Skid steer and compact track loader wheel drives — cartridge-mount configurations bolt directly into final drive housings

Concrete/transit mixer drum drives — steady torque at moderate speed

Drilling rig and winch drives — high torque at controlled, often low, speed

Crusher and conveyor drives — continuous-duty rotary power in aggregate and demolition equipment

Bulldozers and pipelayers — track or drum drive duty in closed-loop HST systems and conveyor drives — continuous-duty rotary power in aggregate and demolition equipment

Bulldozers and pipelayers — track or drum drive duty in closed-loop HST systems

Reading the Model Code and Nameplate

Every 90M075 leaves the factory with a full model code stamped on its nameplate, something like: 90M075 NC 0 N 8 N 0 C6 W 00 NNN 00 00 20`

That string isn't decorative — it fully defines the control type, shaft, port configuration, seal material, and options fitted to that specific unit. When ordering spare parts or a direct replacement, this code (not just "90M075") is what a parts counter or Danfoss distributor actually needs, because two 90M075 motors can differ substantially in shaft spline, port style, and control features while sharing the same base displacement.

Practical tip: photograph the full nameplate — model number, serial number, and model code — before removing an old motor. It saves a return trip and avoids ordering an incompatible shaft or port configuration.

For more information on the 90M075 hydraulic motor, please visit https://www.baolilaihydraulic.com/product/.

Specifications

Selection Table

Q1: How do I know if my motor needs rebuilding versus replacing?

A1: A performance test comparing actual output speed, torque, and volumetric efficiency to rated values is the most reliable way to decide. If wear is confined to seals, bearings, or the valve plate, a rebuild using genuine parts is often more economical than replacement; if the cylinder block, pistons, or housing show significant wear or damage, replacement is usually the better economic choice.

Q2: What machines commonly use the 90M075?

A2: Mid-size excavators (swing drive), skid steer and compact track loaders (wheel drive), transit/concrete mixers, drilling rigs and winches, crushers, conveyors, and various closed-loop hydrostatic propel and rotary-function applications.

Q3:How to purchase a 90M055 hydraulic motor?

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 90M055 hydraulic motor?

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