Rudder Stock Bearing Housing Body

The rudder stock bearing housing body is the housing that carries the bearing bush around the rudder stock where it passes down through the hull or the rudder trunk to the blade. Moreover, it holds the stock on its axis under side load and keeps the gland sealed. Fabricated steel housings distort as the flange and shell welds cool, cocking the bush so it wears unevenly, weeps at the gland and binds the stock. Generally, the bronze-to-steel couple drives galvanic waste of the ferritic shell. A one-piece EN-GJS-500-7 investment casting needs no structural welds. It also needs gives 7 percent elongation with far better vibration damping than fabricated steel, and is finish machined on the bore. It also needs bush seat and flange face after casting so the stock runs true to the drawing axis.

Specifications

Key features

• EN-GJS-500-7 delivers 500 MPa tensile, 320 MPa yield and 7 percent elongation, with damping capacity that cuts vibration transmitted to the gland.
• Ni-Al-Bz bush seat to C95800 composition gives a compatible bearing surface against the rudder stock, with a lower measured wear rate than the tin bronze it replaces.
• Galvanic isolation: an insulating liner separates the Ni-Al-Bz bush from the ferritic housing, breaking the couple that would otherwise waste the iron.
• Bush bore machined to CT5 and concentric with the stock bore within 0.08 mm, removing the cocked-bush wear pattern typical of welded housings.
• Mounting flange face machined flat within 0.15 mm and bolt circle within +/-0.2 mm, so the housing aligns to the stock with no shimming.
• Cast-in lubrication grooves and injector ports feed water or grease to the bearing face without drilled cross-holes breaking through thin walls.
• Zero structural welds in the load path, so there is no weld decay and no post-weld stress relief distortion to correct before final machining.

Applications

• Rudder stock and rudder trunk bearings on harbour tugs and escort tugs.
• Steering gear bearing housings on offshore service and platform supply vessels.
• Rudder stock bearings on patrol craft and fast response boats.
• Rudder and steering installations on dredgers, hoppers and work barges.
• Ferry and ro-pax rudder stock bearing housings and stern tube support bodies.
• Superyacht and large yacht steering system refits and newbuilds.

Quality & compliance

Additionally, Ningbo Ruican casts and machines to IATF 16949 process control and works to ISO 9001 documentation practice. Every shipment carries EN 10204 3.1 material certification tied to the heat lot, with chemical analysis, mechanical test results and the furnace chart for the ferritizing anneal or stress relief applied to the ductile iron. In general, the Ni-Al-Bz bush material is certified separately and traced to its own melt. Also, PPAP and FAIR packages are available to the customer’s submission level. Also, the first article ships with a full dimensional report covering every ballooned feature. Where the drawing calls for it, ferrite count and PMI are performed on stainless variants to the buyer’s specified method. Non-destructive testing and inspection acceptance level are supplied to the standard the buyer names on the drawing and order.

FAQ

Can you work from an existing bearing housing sample?

Yes. Send the sample or a worn housing and we 3D scan the bore, bush pocket, flange and port layout, rebuild a model and return a drawing for your approval before tooling. We confirm stock diameter, bush interference, lubrication method and flange bolt pattern. In addition, where the original is a fabrication we propose a cast revision with uniform wall section, quoted separately. You can compare before committing. Tooling takes five to six weeks.

Do you supply duplex 2205 with a ferrite count and no sigma phase?

Yes for the stainless variants of this housing, and for the mating fastener and gland hardware. Also, duplex 2205 is solution annealed at 1020-1100 C and water quenched, with the furnace chart released with the lot. Where the drawing requires it we report ferrite by point count or magnetic measurement against the 35-55 percent target and verify freedom from sigma and chi phase to your specified method. The standard housing body remains EN-GJS-500-7 with a Ni-Al-Bz bush seat.

What is the minimum order quantity?

We accept prototype and pilot quantities from a single tooling set, which suits steering refits and single-vessel work, then scale to series production with multi-cavity tooling once annual volume justifies it. For housings in this size range the practical first release is around 20 to 50 pieces. Generally, tooling is maintained and stored for repeat orders across the vessel programme, and we can hold agreed safety stock.

Do you machine the parts fully in-house?

Yes. Casting, heat treatment, CNC turning, CNC milling, boring, drilling and surface finishing all run inside our Ningbo facility under one IATF 16949 control plan. Holding every operation in-house means the bush bore and the stock bore are finish machined in related setups from the casting datums, so concentricity within 0.08 mm is verified against your drawing by one inspection team before release.

Can you match an existing class-approved part?

We reverse engineer an existing part, match the drawing geometry, material and heat treatment, and supply EN 10204 3.1 certification, dimensional reports and NDT evidence to the standard you specify. Moreover, Ningbo Ruican holds no classification-society type approval and claims none; any class survey. It also holds plan approval or type approval remains the responsibility of the shipyard. It also holds the equipment maker and the society. Generally, we supply the evidence package your surveyor reviews.

CTA

Send your rudder stock bearing housing drawing, sample or 3D model for a DFM review, bearing clearance study and tooling plus piece price. Contact Wendy She — sales@cnsandcasting.com — WhatsApp +86-13777124360, or visit https://cnsandcasting.com to start your marine casting program with Ningbo Ruican.