Steering Gear — Most Asked Questions
16 questions asked about steering gear across the General and Fn 3 papers, heaviest first. 1 of them are must-master.
Learn the system first
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1 Tanker steering gear regulation?
Answer
Under SOLAS Ch. II-1 Reg 29, tankers of 10,000 GT and above must meet the Single Failure Criterion: any single hydraulic or power failure must be automatically isolated and steering capability regained within 45 seconds.
- Single Failure Criterion (45-second rule): In the event of a single failure in any pipe, pump, valve, or seal (excluding rudder tiller/quadrant or mechanical actuator seizure), steering capability must be restored in not more than 45 seconds.
- 10,000 GT threshold vs 70,000 GT for other ships: Tankers, chemical tankers, and gas carriers need duplicated identical power units from 10,000 GT upwards; conventional cargo ships only require this at 70,000 GT and upwards (below 70k GT, standard main + auxiliary gear is permitted).
- No simple auxiliary gear allowed: Tankers cannot rely on an auxiliary steering gear (which only requires 15° to 15° at half speed or 7 knots); they must have duplicated main power units capable of full performance (35° to 30° in 28 seconds at maximum service speed).
- Automatic Isolation ("Safematic"): Where systems run interconnected, loss of hydraulic fluid must trigger low-level sensing and automatically close isolating valves within 45 seconds to separate and bypass the leaking circuit, keeping the healthy circuit fully operational.
- Actuator redundancy by deadweight: Below 100,000 DWT, a single actuator is allowed only with strict fatigue and fracture mechanics approval; at 100,000 DWT and above, the rudder actuator itself must satisfy the single failure criterion (e.g., split 4-ram or dual rotary vane).
- Power & storage reserves: A permanently piped storage tank sized to refill at least one complete system is mandatory; emergency power supply must connect automatically within 45 seconds and supply at least 30 minutes of continuous steering.
Surveyor follow-up: What historical incident led to this regulation, and how does the automatic isolation system detect which hydraulic circuit is leaking?
Full theory: Steering Gear Rules — Main and Auxiliary Gear, Performance and Tests -
2 Steering gear type
Answer
Two families: electro-hydraulic ram or rotary-vane gears, and all-electric Ward-Leonard or single-motor gears — rams rule the big ships.
- Electro-hydraulic ram: pump unit drives rams coupled almost directly to the rudder stock; wheel to starboard moves rams port-ward and the rudder to starboard.
- Rotary vane: vanes on the stock turn inside a fixed casing — compact where a ram would not fit.
- All-electric: Ward-Leonard or single-motor drive, now rare on large ships but alive in smaller tonnage.
- Control is follow-up with automatic feedback or non-follow-up where the operator is the feedback — on feedback failure, shift to non-follow-up.
Surveyor follow-up: feedback transmitter fails mid-passage — what steering mode, and what changes for the helmsman?
Full theory: Steering Gear Rules — Main and Auxiliary Gear, Performance and Tests -
3 What is safematic system
Also asked: “Safematic system proper”, “Safematic system explain in depth”, “Ques: Safematic system”
Answer
Safematic is the follow-up brain of the steering gear: wheel order in, automatic feedback out, rudder stopping where ordered.
- Follow-up control: moving the wheel commands an angle and the feedback transmitter drives the rudder there, then hunts it to a stop.
- If the feedback transmitter fails, shift to non-follow-up — spring-loaded lever where the operator is the feedback and centres the rudder by hand.
- Telemotor failure brings its own fallback: local hand or trick-wheel control at the gear, proved at every departure.
- Prove both modes before sailing: hard-over to hard-over timing on follow-up, then a non-follow-up jog each way.
Surveyor follow-up: feedback fails mid-channel with traffic around — which mode, and what changes for the helmsman?
Full theory: Steering Gear Rules — Main and Auxiliary Gear, Performance and Tests -
4 steering gear checks
Also asked: “Steering gear check before dept”
Answer
Check the gear an hour before sailing: oil up, pumps running, rudder answering, alarms proved, talk-back tested.
- Telemotor transmitter and actuating-system tank levels checked and topped; rudder carrier and sea gland greased.
- Start pumps and prove response both units with load carrying and smooth running.
- Bridge-to-gear communication tested with rudder-angle indicators agreeing both ends.
- Alarms for power loss, low oil and overload proved; emergency and local control jogged each way.
Surveyor follow-up: one pump noisy with oil foaming — air, level or suction leak, and do you sail?
Full theory: Steering Gear Checks and Tests — Daily Rounds, the 12-Hour Test and Drills -
5 How steering motor is differ from all other motor? Overcurrent trip is fitted or not on steering motor?
Answer
Steering motors never trip on overload — alarm only, sized for double full-load current with short-circuit cover.
- Overload protection that would stop the rudder is forbidden; overload alarm is mandatory instead.
- Excess-current cover, including starting surge, rates at twice full-load current minimum.
- Exclusive circuits from the main board — one leg may ride the emergency board — sized for every motor running together.
- Three-phase loss gets its own alarm; single electrical failure must never drive a shut door or dead rudder.
Surveyor follow-up: overload alarm sounding hard over in heavy weather — stop, slow or steer on, and who decides?
Full theory: Steering Gear Rules — Main and Auxiliary Gear, Performance and Tests -
6 Sketch and describe in simple form of constant speed hele-shaw pump suitable for a hydraulic steering gear
Answer
Sketch a spinning bronze block with radial pistons on a fixed ported centre: guide-ring shift sets stroke from zero to full either way.
- Seven or nine radial cylinders spin at constant speed round a fixed steel centre with two opposite ports.
- Push-pull rod shifts guide rings to stroke the pistons from zero to full in either direction without stopping.
- Fixed ratchet teeth with inward pawls lock the pump base against reaction torque.
- Output follows guide shift, not speed — centre the rings and flow dies with the pump still spinning.
Surveyor follow-up: full wheel with weak rudder response — guide shift, porting or suction, and what do you move first?
Full theory: Ram Type Steering Gear — Two and Four Rams, Valve Chests and Change-Over -
7 Steering gear checks before leaving port
Also asked: “Steering gear checks before arrival”
Answer
Check the gear an hour before sailing: oil up, pumps running, rudder answering, alarms proved, talk-back tested.
- Telemotor and actuating-tank levels topped with carrier bearing and sea gland greased.
- Start pumps and prove response both units with load carrying and smooth running.
- Bridge-to-gear communication tested with indicators agreeing both ends.
- Power-loss, low-oil and overload alarms proved with emergency and local control jogged each way.
Surveyor follow-up: one pump noisy with oil foaming — air, level or suction leak, and do you sail?
Full theory: Steering Gear Checks and Tests — Daily Rounds, the 12-Hour Test and Drills -
8 Q6.) How is a Four ram type steering gear is maintained including daily maintenance at sea explain all the maintenance of hydraulic system?
Answer
Four-ram maintenance is oil, air and grease: levels, cleanliness, tightness, and the oil kept in condition on the ship’s own system.
- Daily at sea: hydraulic oil level and condition, the temperature and pressure, and a look for weeps at the rams and pipe joints.
- Check the telemotor and the hunting gear movement, and confirm the rudder indicator agrees with the actual angle.
- Keep the system clean, the oil tight and the pressure right — and if a separate oil system is used, replenish it as required.
- A four-ram gear is the torque of the ship, so a fault there is a steering casualty; treat the oil temperature as an alarm, not a reading.
Surveyor follow-up: four-ram gear running hot with the oil level correct and the cooler clean — is the relief, the pump or the ram?
Full theory: Ram Type Steering Gear — Two and Four Rams, Valve Chests and Change-Over -
9 Sketch a two-ram type hydraulic steering gear with a single Electro-hydraulic pumping unit, Show the hunting gear arrangement and indicate valve positions. (8) (b) State the purpose of, and describe the operation of:- (8
Answer
A two-ram gear on one pump: the telemotor moves the hunting lever, the pump follows, and the rams follow the rudder back to neutral.
- Draw the pump, the control valve, the two rams and the hunting lever, with the valve positions in mid-ship and at hard over.
- The bridge helm drives the telemotor, which moves a floating lever on the pump control; the pump then delivers to the ram.
- The other end of the lever is linked through a safety spring to the rudder stock or tiller.
- When the rudder reaches the ordered angle the stock turns the hunting gear and returns the pump operating rod to neutral.
Surveyor follow-up: helm held over and the pump still delivering — is the hunting gear, the spring link or the rudder angle?
Full theory: Ram Type Steering Gear — Two and Four Rams, Valve Chests and Change-Over -
10 Special properties of hydraulic oil of steering gear???
Answer
Steering oil is a gear oil that also must not freeze, not foam, and not squeeze metal-to-metal at the clearances it runs in.
- High viscosity with film strength to prevent metal-to-metal contact, plus adhesion to the metal against sliding and centrifugal force.
- Antiwear additives for the gear teeth, and a high viscosity index so the viscosity holds over the ship’s temperature range.
- Anti-freeze additives, because the oil sits in a tank in a cold sea on a ship at anchor.
- Antifoaming and sound-damping properties, and it must not shear down in service or the gear will start hunting.
Surveyor follow-up: steering gear hunting warm with the oil at the right grade — is it aeration, the hunting gear or the oil shear?
Full theory: Steering Gear Safety — Stored Energy, Isolation and Enclosed Space Entry -
11 Steering gear operation
Answer
The wheel moves a telemotor, the telemotor moves the hunting lever, and the hunting gear feeds the pump only while the wheel is turned.
- The telemotor receives the bridge signal and moves a floating lever, one end of which drives the pump control rod.
- The pump delivery moves the ram, turning the rudder stock and putting the rudder over.
- The other end of the floating lever connects through a safety spring link to the rudder stock or tiller.
- When the rudder reaches the ordered angle, the rudder stock turns the hunting gear and returns the pump to neutral — so the pump only delivers while the wheel moves.
Surveyor follow-up: helm ordered and held but the pump runs on and the rudder creeps — is the hunting gear link or the spring link at fault?
Full theory: Steering Gear Control Systems — Telemotor, Hunting Gear and Floating Lever -
12 Steering gear safetites
Also asked: “Steering gear & windlass safety devices”
Answer
Steering safeties are the buffer, the stops, the reliefs and the alarms — each one catches a different way the gear can kill a ship.
- Hunting gear, buffer spring and an angle-adjusting stop with a hand-over position limit switch bound the ram travel.
- A double shock valve and a relief valve protect against a ram shock or a pressure overload.
- Tank level and oil temperature alarms warn of loss of reserve or overheating of the hydraulic oil.
- Airstrike indication — jumping pressure gauges, jerky operation and defective steering — means air in the system is the fault to find.
Surveyor follow-up: gauges jumping and the gear jerky on hard-over — is it air, the relief or the buffer spring first?
Full theory: Steering Gear Safety — Stored Energy, Isolation and Enclosed Space Entry -
13 Steering motor safety if one motor running (locking arrangement
Answer
A locked-out second motor is a safety device, not a fault — it stops the idle pump being dragged round by the running one.
- Non-reverse locking gear in the flexible coupling stops the idle pump being driven backwards by the running pump.
- Steel pawls on the motor coupling rim are thrown out by forward rotation and drop into the notches in reverse.
- Some installations also lock out the idle unit mechanically so its motor cannot be started by accident.
- Prove the arrangement on the trial: with one pump running, the standby must not turn — and it must be free to run when started.
Surveyor follow-up: standby pump turning backwards on trial with the pawls fitted — is the pawl damaged or the coupling free?
Full theory: Steering Gear Failures — Relief Valves, Split Circuits and the Alarm Chain -
14 Why use vane type pump in steering system
Answer
Vane pumps are chosen for a quiet, smooth, compact unit — they take less space, weight and power for the same rudder torque.
- Smaller space, lower installation cost and lower weight than an equivalent ram-type arrangement.
- Less power is needed for the same load because pure torque is transmitted straight to the rudder stock.
- Flow is smooth, which is why the gear does not hunt and the telemotor signal is followed without surge.
- The limitation is real: synthetic rubber-backed sealing strips at the vane tops are not strong enough for very high pressures.
Surveyor follow-up: vane pump overheating on hard-over with the relief clean — is the oil, the strip material or the pressure?
Full theory: Rotary Vane Steering Gear — Principle, Pressure Limit and Ram Comparison -
15 With reference to Steering Gear & Hydraulic Power Rotary pumps (a) Explain how the reserve of fluid in the system is checked and how make-up 1s achieved. (5) (b) Describe how a steering system is tested prior to leaving
Also asked: “With reference to Steering Gear & Hydraulic Power Rotary pumps (a) Explain how the reserve of fluid in the system is checked and how make-up 1s achieved. (5) (b) Describe how a steering system is tested prior to leaving port with reference to i (c) Explain how tests are made for leaks, and air and other gases are bled from the system”
Answer
The reserve is read on the sight glass and the system is topped and bled before the ship sails — then the whole range is proved.
- Check the oil reserve by sight glass against the maker’s mark, with the pump stopped so the level is true.
- Make-up is by topping the tank through the fill and vent points, never by cracking a gland at the ram.
- Bleed the system at the highest points until the gauges hold steady — trapped air is what makes a gear hunt.
- Test before departure: run the ram hard over to both sides, check for leaks, and confirm the actual rudder angle at hard-over.
Surveyor follow-up: reserve full and the gear hunting on the voyage test — is it air, the hunting gear or the actual angle?
Full theory: Steering Gear Safety — Stored Energy, Isolation and Enclosed Space Entry -
16 With reference to rotary vane steering gears: (a) Describe, with the aid ofa sketch, how such a unit incorporates an integral rudder carrier
Answer
The carrier is built into the unit: a single housing carries the rudder stock bearing and the pump that drives it, so the tiller cannot be separate.
- The rudder carrier is integral with the unit, carrying the stock bearings in the same housing as the steering pump.
- That removes the separate tiller and carrier arrangement, shortening the load path from ram to rudder.
- The result is a compact, stiff unit with no slack between the pump and the stock — which is what stops hunting.
- The same integral housing also carries the seals and the tiller head, so a stock bearing fault is found in one place.
Surveyor follow-up: hunting gear hunting with the unit serviced and the oil clean — is the integral carrier, the pump or air in the oil?
Full theory: Rotary Vane Steering Gear — Principle, Pressure Limit and Ram Comparison
Source: 123 written papers and surveyor oral banks, 24,613 entries, merged into 17,210 topics. Ticks are stored on this device only.