Answer MEP Question 35

Q. What are the effects of following on the sluggishness of steering gear operations?

A. Air entrapped in hydraulic oil;

B. Worn pins and weak springs in hunting gear;

C. Shock valves leaking.

A. Air in the system Air in the system can be identified by a jumping pressure gauge and abnormal noise from the pump.

As a result of air in the system, the steering will be inaccurate, the steering gear will react slowly and movement will be jerky.

Air can enter the system through the non-airtight suction line of the pump, glands of the pump, v-packing of Rams, filters, and from low oil level tanks.

Air in the system is dangerous for the pump and responsible for error in operation; this is required to be vented out of the system.

Every cylinder is mounted with an air vent. Open the air vent valve when the ram is moving in such a way that the air vent is on the high-pressure side. Keep it open till the bubble-free air starts to come out. Repeat this for every cylinder.

B. Worn pins and weak springs in hunting gear

Worn Pins

Worn pins of the hunting gear will cause excessive clearance of pin of pump control unit and repeat back unit, it will not allow the rudder to stand still and cause excessive hunting. Also it will cause faulty response. The worn pins should be renewed.

Weak spring

Spring is fitted between the tiller arm and link connecting the floating lever at the repeat back side. It is a safety spring also called Buffer spring that prevent damage to the control mechanism. A weak spring will cause a slow response to the floating lever and this will result delay in the pump control to react. The start of rudder rotation and stopping will not be instant. The spring must be to be tested  and replace as per the makers recommendation.

C. Shock valve leaking

Shock and bypass valves are fitted between each pair of ram. These valves Lift and release the oil pressure from the high-pressure side of one ram to the low-pressure side of the other rams in pairs. They act when subjected to a severe shock from heavy seas and cause the rudder to return to its former position.   If shock valves are leaking, the rudder movement will be sluggish due to the flow of oil from the high-pressure side to the low-pressure side resulting in less force or less torque for turning. Indication of the leakage of shock and bypass valve are slow speed of rudder turning and rudder movement with wave force.