It is surely the more resistant propeller shaft mechanical seal on the market. The MTM400, in comparison with all the existing propeller shaft mechanical seals, is the first in the world to be equipped with a double series of springs.
This allows it to better compensate for angular and radial misalignments. Moreover, springs together with a double system of o-rings give rise to what Microtem has named DEDaS® (Double Elastic Damping System), that is an elastic damping system able to make the MTM400 resistant to 60 g shock and to 60 mm/s (RMS) of vibration.
Inside of it, in the rotating part, there is another international recognised innovation: the pumping ring. This technology, newly introduced in the propeller shaft seals, ensures that the cooling fluid (usually water) is distributed to a greater and better extent on the sliding faces, increasing the heat dissipation and thus reducing consumption. All this allows MTM400 to achieve performance over 60.000 hours of operation before maintenance. Of equal importance is the design, as its compact size allows the seal to be one of the axially smaller solutions in the world.
Thanks to the “Repair Kit” in two halves the maintencance can be caried out directly on the mechanical seal without decoupling the shaft from the coupling. Additionaly, the MTM400 together with the hydraulic barrier system (Watershield) allows to carry out maintenance with the boat in the water. It is designed for shafts with diameter 50 mm to 800 mm, and it is certified by RINA. There are different possible material configurations and it is the only product to be certified, as standard, for fire resistance. The stationary flange can be designed with a maximum of 6 radial holes that allow to connect: one or more auxiliary cooling lines for the bearing, a pressure gauge, a temperature gauge, a flow gauge or a axial/radial vibration sensor. Suitable for all applications, it is the best product for mega yachts, passenger and military vessels.

Operating limits:

D= 50 – 800mm
P1= 2.5 bar
T= - 40 a + 400°C
V= 20 m/s.
Axial movement: up to +/- 8.0 mm
Radial movement: up to +/- 6.0 mm
Angualr movement: up to 2°



Face materials:

Silicon carbide
Tungsten carbide
Antimony carbon
Resin carbon

The only Fire resistant one

Technical Drawing


1. Stationary holder
2. Rotary holder
3. Centering sleeve
4. Stationary ring
5. Rotary ring
6. O-ring flange
7. O-ring
8. O-ring
9. O-ring
10. O-ring
11. O-ring
12. O-ring
13. Screw

14. Grub Screw
15. Screw
16. Connection For Water Inlet
17. Elastomer Ring For Watershield
18. Compression Ring
19. Centering Ring
20. Connection For Air Inlet
21. O-Ring
22. Screw
23. Spring
24. Spring
25. Preload Screw


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