DUO (Diagnostic Unit Oil aging) diagnostic unit

Monitor the temperature and remaining gear unit oil service life of your drive technology with simple thermal analysis – at any time, even during production. The benefit to you: DUO's measurements allow you adjust the maintenance intervals of your gear unit perfectly to suit your work processes. This makes planning those processes much easier, and increases the efficiency and economic viability of your machines and systems.

Keeping an eye on the remaining service life of your oil

DUO diagnostic unit
DUO diagnostic unit
DUO diagnostic unit

The DUO (Diagnostic Unit Oil aging) diagnostic unit carries out a thermal analysis on your gear unit oil. A thermal sensor measures the oil temperature and sends this information to an evaluation unit, which then calculates the time remaining service life for the specified oil type.

All you need to do is define the limit values so that DUO can send you a warning message when they are exceeded. In practice, this means that you can keep an eye on the remaining oil service life – and thus the performance – of your mechanical drive technology at all times.

Diagnostic units are the perfect partner to our gear units. They help to monitor the remaining oil service life during operation, perform diagnostics and optimize maintenance intervals.
All of these facts make these diagnostic units an important component of any condition monitoring concept.

Get in touch with us.

  • Our experts know your industry and its requirements.
  • Our global network ensures we are there wherever and whenever you need us.
  • We have the expertise and tools to provide optimum advice and support.

Your benefits

  • Simple and fast

    sensing and reading of the oil temperature and its remaining service life.
  • Reliable

    warning messages issued if the predefined limit values, such as max. oil temperature, are exceeded.
  • Individually planned

    maintenance intervals allow optimum utilization of oil service life and reduce maintenance costs.


  • The perfect sensor for determining the remaining service life of the gear unit oil and reliably indicating the right time for an oil change
  • A thermal sensor installed in the gear unit measures the oil temperature and sends this information to an evaluation unit, which then calculates the remaining service life for the specified oil type
  • The diagnostic unit takes into account the oxidation characteristics of the different oils under thermal stress

Technical data

Close table
Technical data Value
Types of oil

  • Mineral oil CLP or bio oil
  • TMax. = 100°C

  • Synthetic oil CLP HC or CLP PAO
  • TMax. = 130°C

  • Polyglycol CLP PG
  • TMax. = 130°C

  • Food grade oil
  • TMax. = 100°C

Permitted oil temperature -40...+130°C
Permitted temperature sensors PT100 or PT1000
EMC EN61000-4-2 ESD: 4 kV CD/8 kV AD
EN61000-4-3 HF blasted: 10 V/m
EN61000-4-4 burst: 2 kV
EN61000-4-6 HF cable-conducted: 10 V
Ambient temperature -20...+70°C
Operating voltage DC 18 ... 28 V1)
Current consumption at DC 24 V < 90 mA (when display is active)
Protection class III
Degree of protection IP67 (optionally IP69K)
Housing materials Diagnostic unit
V2A; EPDM/X (Santoprene); PBT (Pocan); FPM (Viton)
Temperature sensor V4A
Electrical connection Diagnostic unit M12 plug connector
Temperature sensor

  • PT1000: M12 plug connector
  • PT100: Plug connector in line with DIN 43650

  1. 1) in accordance with EN 50178, SELV, PELV
We have stored a table for you here.

Gear unit combinations

Helical gear unit, sizes R67 - R167

Parallel-shaft helical gear unit, sizes F57 - F157

Helical-bevel gear unit, sizes K37 - K187

Helical-worm gear unit, sizes S67 - S97

For installation on small sizes or industrial gear units, please contact SEW‑EURODRIVE.

Areas of application

  • The DUO diagnostic unit is recommended for us in a wide range of industries and areas of application. The continuous monitoring of the remaining oil life makes it possible to determine the optimum time to change the oil.
  • This is especially useful when working with fluctuating loads, speeds and ambient temperatures. Such conditions make it difficult to calculate the optimum time for an oil change using service life curves.
  • The DUO diagnostic unit can also reduce the risk of failure in critical systems where machine and production standstills are associated with high costs.

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