Q: Who is responsible for the mounting of the transmission to the engine?
A: If we fit it then we will take responsibility for the mounting and support to the engine. If we don't, that responsibility lies
with the engine supplier or fitter that has undertaken the process.
Q: Who is responsible for the mounting / support of the transmission to the vessel?
A: If we supply and fit then Pacific Driveline Ltd will cover their work. As there are a vast amount of options that can be applied to support bracketing to allow for movement under thrust, there is no universal answer. Twin Disc supply some generic advice but each application must be viewed on an individual requirement. If Pacific Driveline Ltd are not contracted to do this work – either design or supply and fit then it becomes the responsibility of the engineers that are fitting the engine, transmission and drivetrain to the vessel.
Q: Who is responsible for transmission ratio selection?
A: This can only truly be quantified by the propeller supplier as the chosen reduction has a direct effect on the applied torque and thrust – to match the hulls resistance. Some engine suppliers have this capability.
Q: Will the same transmission operate the same in different vessels?
A: No – different vessels have different characteristics (apparent after sea trial) and as such input-coupling changes may be required at the owners expense.
Q: How important is the interaction between transmission and control system?
A: The relationship is critical to ensure that the correct amount of engagement is achieved & the engine input speed is correct when transmission engaged.
Q: What is Torsional Vibration?
A: The periodic variation in torque of a rotating system. Causes of torsional vibration are typically gas pressures in internal combustion engines creating peak torques, inertial unbalance or irregular torque requirements of rotating equipment. It is important to note that torsional vibration calculations are typically analysed for the continuous steady state, rather than the transient start-up or run-down condition.
Q: Who is responsible for ensuring torsional compatibility?
A: “Disregarding propulsion system torsional compatibility could cause damage to components in the drive train resulting in loss of mobility. At minimum, system incompatibility could result in gear clatter at low speeds. The responsibility for ensuring that the torsional compatibility of the propulsion system is satisfactory rests with the Boat builder, Vessel Owner and or assembler of the drive and driven equipment. The engine builder, marine survey societies, independent consultants and others can make torsional vibration analysis. Twin Disc is prepared to assist, if requested, in finding solutions to potential torsional problems that relate to the equipment of Twin Disc Inc.’s supply.”
Q: Who pays for the Torsional analysis?
A: The vessel owner.
Q: What is gear clatter?
A: Backlash experienced between gear teeth @ low RPM. The effect is normally noise and can be improved by applying a more suited input coupling. This is only discovered after sea trial so expenses related to any changes are the owner’s care.
Q: What is gear whine?
A: Gear whine can be caused by many factors but the most common cause is the use of spur gears (i.e. gears with straight cut teeth). The whine is a physical characteristic of this type of gear and can be more pronounced in some installations and less so in others. In older transmissions it can be very difficult or even impossible to eliminate this whine. In order to reduce gear whine Twin Disc now use helical cut gears for quieter operation. Even with helical gears, whine can sometimes still be evident.
Q: What can be done about gear noise (clatter & whine)?
A: Various changes to the driveline can be made including changing the input coupling and or output coupling. In extreme cases it may also be necessary to change internal gears or other driveline components. All changes are at the customers discretion and cost.
Q: Is the transmission tested after rebuild?
A: Yes – any transmission rebuild in our workshop is “spin tested” (no load) in a similar manner to that used in the Twin Disc assembly plant. This is to ensure that specified running pressures are achieved and there are no oil leaks before installation back into the vessel.
Q: What are common transmission failures?
A: Clutch Failure due to low oil pressure – caused by not fully engaging control levers, damaged piston rings, damaged oil pump, poor flow rate thru G/Box coolers or loss of oil.
Q: What happens if there is a vibration?
A: Pacific Driveline do not accept any responsibility for vibration levels on sea trial as the resulting combinations of machinery and vessel make it impossible to pre-define a level of tolerance unless an in-depth design study and TVA is undertaken by the client before any equipment is fitted to the vessel.
Q: How often should I check the oil level?
A: Daily or every 10 hours of operation. Check at normal operating temperature with engine running at low idle and transmission in neutral.
Q: How often should I change the oil?
A: After the first 50 hours and thereafter every 1,000 hours of operation or 6 months whichever occurs first. Check lubrication plate for oil specifications.
Q: Should I fit oil gauges?
A: Yes, fitting of oil pressure gauges on the transmission is strongly recommended and considered imperative where trolling valves are fitted. Fitting of oil temperature gauges is also good but not as important as pressure gauges.
Q: Can you connect battery power directly to the Fema valves on a MGX Transmission?
A: No. Damage will result to the solenoids and clutch.