Tenfjord Steering
Gear Spare Parts Supplier
SR and SV types · Rotor and vane seals · Locking ring assemblies
One machine, four company names and two actuator families
Steering gear reaches this site through its hydraulics: the actuator is worked by the same kind of power pack met on valve remote control systems, and sits in the wider group on engine room equipment. The identification problem is this maker's own.
The lineage runs four deep
Tenfjord was an independent Norwegian works; Ulstein took it over and the product became Ulstein Tenfjord; Vickers and then Rolls-Royce took the greater part of that group in 1999; Kongsberg completed its purchase of the Rolls-Royce commercial marine business on 1 April 2019; and in September 2024 Norvestor agreed to buy Kongsberg Maritime's steering gear and rudder business, which now trades as Neuver Maritime from Brattvåg in Norway. Plates in service therefore read Tenfjord, Ulstein Tenfjord or Rolls-Royce, while the current SR and SV maintenance manual is issued by Neuver Maritime.
The rotary vane actuator on a spherical rotor
The SR designations run from SR562 upward, with an L variant at the lower end. The maker's own literature gives the distinguishing feature plainly: the series uses a spherical rotor bearing, which improves how force is distributed from the rudder stock into the rotor, and the synthetic bearing keeps its whole surface in contact even while the stock flexes, absorbing vibration and shock pulses.
Spherical vane, built the other way round
The SV designations are a different construction, not a larger SR. Trade reporting of the type describes the vanes as integrated into the rotor, the dividing segments set in a toroidal groove in the housing, and the rotor and both housings made of nodular cast iron. A seal ordered from an SR drawing does not describe the same joint on an SV.
Two hydraulic worlds under one type name
The same actuator is delivered either with frequency-controlled reversible pumps mounted on it or with separate conventional pump units. On the first, a motor starts when a rudder order arrives and stops when the rudder reaches the ordered position, and a blocking valve holds the position. On the second the pumps run continuously and a manoeuvring valve directs the oil. Filters, valves, couplings and converters differ accordingly.
The actuator is built to tolerate a rudder stock that moves
Three design facts explain most of what turns up in a Tenfjord enquiry, and none is on the nameplate.
The vanes work in a rotor of spherical shape centred on the rudder stock, and they are fastened to that rotor so that they can take up and follow the rotor's spherical deflection — deflection caused by misalignment at installation or by the stock itself bending under load. That is a tolerance built into the machine, not a promise that the forces go away. The maker's maintenance guidance says as much when it lists what decides how long seals and bearings last: alignment of the rudder stock and the gear comes first, radial forces from the rudder and the way the ship is steered second. A gear that has eaten two sets of seals is therefore an alignment and rudder-carrier question, and the sensible request carries the last alignment record beside the seal reference.
The bearing is lubricated by the hydraulic oil in the actuator. That rewrites the oil question: oil condition here is not only a pump-life matter, it is the bearing's lubrication, and the maker asks for samples drawn from the actuator rather than only from the tank. Oil is changed on laboratory evidence — neutralisation number, remaining additive, insoluble particles, a cleanliness class on the usual ISO scale — and mixing brands is discouraged in strong terms. When a bearing-pad order arrives without an oil history, that history is the first thing we ask for.
The third fact is about the stock. Its upper part is cylindrical across the range of shaft sizes, which the maker points out makes it simpler to manufacture, lets the height of the gear be adjusted, and means the length need not be exact. The gear is joined to it by locking ring assemblies rather than by a key and a tiller. Two consequences: the height at which the actuator sits is an installation decision, so the drawing alone is not enough; and a hardware line here concerns locking rings, not keys.
What gets ordered against a rotary vane steering gear
Listed as the machine is divided: the actuator, the joint to the stock, the hydraulic pack in its two forms, then control and feedback.
- Actuator seals for the rotor and the dividing segments
- Synthetic bearing pads, upper and lower, and housing joint seals
- Piston bolts, vane fastening hardware and rudder stock locking ring assemblies
- Distribution valve internals: non-return, load control and relief valves
- Solenoid-operated isolating valves and their magnetic coils
- Manoeuvring valve components on conventionally pumped installations
- Reversible pump units on frequency-controlled installations
- Vane pumps and gear pumps on conventional pump units
- Flexible couplings between motor and pump, and bell housings
- Electric motors, frequency converters and vibration dampers
- Return and duplex filter elements and blockage indicators
- Rudder feedback units, linkage and feedback potentiometers
- Proximity switches, load sense valves and oil sampling plugs
- Control panel items: phase failure relays, selector switches, main contactors, pump control cards, power supplies and the emergency steering push buttons
- Expansion tank fittings and level gauge glasses
- Air oil coolers where fitted, rubber hoses, fittings and bonded seals
- Overhaul seal and bearing sets quoted per actuator designation
Seals and bearing pads are ordered together and against the actuator designation, because reaching the lower ones means lifting the rotor. The maker gives rubber seals a recommended shelf life of no more than five years, so a set bought well ahead of the docking, or one already among the ship's spares, is checked by its date before it is fitted. The hydraulic side of the request is a different document from the electrical side: the maker prints the electrical data inside the cabinets, not on the machine. Related hydraulics sit on marine valves and pipe system components.
The two numbers on the housing, and what has to go with them
The maker's own spares request asks for more than a type: which ship, which installation, which position on which drawing. A useful template for an enquiry sent anywhere.
- Steering gear type as stamped, every character: the maker's own tables list SR722 and SR723, SR742 and SR743 as separate rows, the L of an SR562L is part of the type, and SV types carry a dash suffix such as SV650-3
- Installation number from the same plate on the housing, which ties a machine to its own drawing set
- Which name the plate and the manuals carry: Tenfjord, Ulstein Tenfjord, Rolls-Royce, Kongsberg, or Neuver Maritime on current maker documentation
- Vessel name and IMO number, since maker records are held against the ship
- Drawing number, position number and article number, where the documentation is aboard — the maker's own spares order asks for all three
- Whether the pumps are frequency controlled or conventional, and how many are installed
- Pump unit designation on a conventionally pumped machine (PU30, PU45 or PU50 in the maker's manual) and the manoeuvring valve reference, plus the valve block type on either kind, since the maker lists its repair kits by valve block, such as FV4-01 or FV9
- Electrical data from the sticker inside the cabinet, photographed rather than transcribed, and whether the steering gear performance monitoring system is fitted, with its log files for the last twelve months
- Results of the last internal leakage test and timed rudder movement, with oil temperature and pressure
- Oil type in the system, the date of the last change and the last laboratory report
- Date and result of the last rudder stock alignment check, for any seal or bearing line
- Whether one gear is installed or two, and which unit this concerns
- Clear height above the gear, measured if possible: the maker's manual names a minimum free height for lifting the rotor in place, below which the yard has to open the deck above or lower the rudder
- Class society and the date of the next survey, since completed actuator work is surveyed
- Photographs of the housing plate, of the cabinet sticker and of the leak or component in place
Tools for this equipment: the lubricant code reader for the hydraulic oil, the oil cleanliness code reader for an oil analysis report and the hose assembly builder for the hoses. For the steering gear pumps, the hydraulic displacement calculator works out the flow from the displacement on the pump plate and the motor speed.
A survey item, a consumable and a converter walk into one requisition
Steering gear requests arrive mixed, and the three kinds of line in them are not answerable alike.
The actuator overhaul is the hard end. Seals, bearing pads and the joint between the housings are changed as one job, in dock, with the rudder secured and the rotor lifted, and the maker's own recommendation ties that work to docking and survey rather than to running hours. The class society then surveys what was done. So an actuator line is a planning question before a purchasing one: the parts follow the docking window, and a set ordered without a window tends to be ordered twice. Vessel Core puts these lines on an OEM-route review, and where the service history is thin we say which drawing the reference was checked against.
The rest divides cleanly. Filter elements, hoses, bonded seals, fittings, gauge glasses, magnetic coils, proximity switches, flexible couplings and vibration dampers are ordinary supply questions with measurable geometry and stated material, and a verified alternative route can be reviewed on them where a buyer's approval requirements allow, with dimensional and material documentation checked at RFQ stage. Frequency converters, control cards, feedback potentiometers and the pumps sit in the middle: replaceable items with a designation of their own, where the route depends on whether the machine is resurveyed afterwards. Vessel Core is an independent spare parts supplier and puts the proposed route against each line, so a list holding all three kinds is answered as three.
Tenfjord steering gear parts — common questions
My plate says Rolls-Royce, or Ulstein Tenfjord. Who supports the machine now?
Neuver Maritime of Brattvåg, the company formed when Norvestor agreed in September 2024 to buy Kongsberg Maritime's steering gear and rudder business; its name is on the current SR and SV maintenance manual. Kongsberg had held the line since completing its acquisition of the Rolls-Royce commercial marine business on 1 April 2019. Before that the plate carried Rolls-Royce, and before that Ulstein Tenfjord. The machine did not change when the name did. Send the type and the installation number as stamped; we work from those, not from the badge.
Can you quote a vane seal from the type designation alone?
The type narrows it and the installation number settles it, which is why both sit on one plate on the housing. Seals and bearing pads are also ordered as a set, because the lower ones cannot be reached without lifting the rotor and nobody opens that job twice. Where the plate is unreadable, the drawing set and its position numbers do the same work.
Why do you ask about rudder stock alignment when I asked for seals?
Because the maker names it first among the things that decide how long seals and bearings last, ahead of oil condition and duty cycles. The actuator is built to accommodate a stock that deflects, the vanes being fastened to the rotor so they can follow it, but accommodation is not immunity. A second set of seals in a short period is telling you something about the carrier, and we would rather ask than sell the same kit again.
Do I really need the deck opened to change actuator seals?
Only where the compartment is tight. The lower seals and bearing pads are reached by lifting the rotor, so the rudder is blocked and secured by the yard and lifting gear is rigged. Where there is too little clear height above the gear, the yard may need to open the deck above the steering gear room or lower the stock instead. That is a yard decision and a yard responsibility, and it sets the docking window the parts have to arrive for.
Is Vessel Core connected to Kongsberg Maritime or Tenfjord?
No, and there is no agreement of any kind. Vessel Core holds no dealership, distribution, representation or partnership agreement with Kongsberg Maritime or Tenfjord, and quoting a component against one of their designations implies no approval by the maker and no claim of interchangeability.
Submit your RFQ now.
Send your Tenfjord request — actuator seals, bearing pads, distribution valves or feedback units — with a photograph of the unit's own plate. A plate reading Rolls-Royce, Ulstein Tenfjord or Kongsberg instead of Tenfjord is the same machine under a later ownership name.
