BNF weldable propulsion system (mild steel stern tube) 

The BNF grease lubricated propulsion system, using a mild steel weldable stern tube, is quite well known and is applied for many years now to high customer satisfaction. It is a reliable and tested system with the advantage the propellers shaft does not necessarily has to be made of stainless steel. The thick-walled mild steel stern tube is to be welded in the boat casco. A mild steel welding sleeve (L=100mm) is separate delivered with the stern tube. On request more and/or longer welding sleeves can be supplied. Welding has to be performed with care, to prevent high welding stresses in the stern tube causing deformation and/or bending (bearings will no longer be aligned).

The stern tube is executed with bronze plain bearings and is to be fully filled with waterproof grease. On the inside the bearings have grooves, to provide optimal lubrication. All bearings are individually locked with a locking bolt, making it possible to replace if needed. When bearings are replaced the stern tube is remaining in the aligned position. Grease is supplied directly onto the stern tube, between the bearings. This way the grease will easily access the bearings. The connection for grease-supply is positioned to the front side of the stern tube (inside the boat) in order to have accessibility.

At the front side the stern tube is executed with a integrated stuffing box with brass gland pusher. Gland packing is included in the delivery.

Download here the Drawing BNF grease lubricated stern tube system (pdf). It can be used for a request for a quotation or to send us your purchase order directly.

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