James Walker - Marine propulsion

Azimuth systems

Wher Azimuth propulsion system overview e propulsion and steering are combined in azimuth thruster or POD propulsion systems the demands on the sealing systems are at their most challenging. Rapid changes in direction of forces and shock loads require the seals to be robust in construction yet highly responsive.

Maximum sealing integrity combined with ease of fitting and maintenance are primary features of the thruster seal arrangements designed by James Walker.

• Propeller shaft seal
The reco Azimuth prop shaft seal arrangement mmended seal arrangement consists of four seals; two seals facing the seawater and a second pair to retain the bearing lubricant. The space between each seal pair must be lubricated to prevent dry running, overheating and premature wear.

Walkersele® D7 and Walkersele® D8 profile seals are recommended for this position as there will usually be a certain amount of pressure from the head of seawater.

• Azimuth swivel seal
Robust Walkersele® D7 and Walkersele® D8 profile seals are ideally suited to the pressures and demanding mechanical conditions encountered in this application.

In larger units the bearing clearances and side loadings which may be encountered in operation can lead to quite high levels of eccentricity. In these instances our Technical Support Team can normally design application specific seals to suit.

• Input shaft seal
The normal recommendation for this sealing position would be for Walkersele® D6 or Walkersele® D8 profile. In view of its inaccessibility it is common to fit two seals in tandem as shown, but care must be taken to ensure that the back-up seal is lubricated.

An alternative method is to hold the back-up seal clear of the shaft by means of a thin-walled metal sleeve which can be removed when the primary seal wears allowing the second seal to operate.