MRG, Shafting & CPP ESWS Study Guide PDF

MAIN REDUCTION GEAR (MRG) AND SHAFTING The purpose of MRG is to convert the high speed, low torque input of the GTM’s to a low speed, high torque output of the shafting and propeller. PHYISCAL DISCRIPTION OF THE MRG Double input, two engines input to the MRG Double reduction, reduce...

MAIN REDUCTION GEAR (MRG) AND SHAFTING The purpose of MRG is to convert the high speed, low torque input of the GTM’s to a low speed, high torque output of the shafting and propeller. PHYISCAL DISCRIPTION OF THE MRG Double input, two engines input to the MRG Double reduction, reduces speed two times Double helical, v shape gears better for thrust and reduces noise Single Output, one shaft Articulated Locked train, all gears for rotate together The main engines are connected to the MRG via a HIGH SPEED FLEXIBLE COUPLING SHAFT (HSFCS). SYNCHRONIZING SELF-SHIFTING (SSS) CLUTCH The SSS clutch in located in the MRG port and starboard side Purpose is to engage and disengage the main engines to MRG When clutch engage the main engine will be rotating the MRG, and when engine is stop at lower speeds the SSS clutch will disengage POWER TURBINE BRAKE PT brakes holds the power turbine stationary until the engine is place online BRAKE MODE Is only use in emergency conditions only When activating brake mode it will decrease the speed of the GTM to idle and the PT brake will engage at 2200 rpm MAIN THRUST BEARING Purpose is the absorbs axial thrust from the shaft and transmits it to the hull of the ship Each MRG has its own thrust bearing starboard one is located in Aux2 and port one is located in shaft alley LINE SHAFT BEARING Purpose is to support radial support of the shaft Starboard shaft has 2 line shaft bearing, 1A located in MER2 and 1B located in shaft alley Port shaft has 1 line shaft bearing, 2A located in shaft alley STRUT BEARING  Purpose it to support the weight of the shaft and radial support as well. Each shaft has a strut bearing that is located outside the hull of the ship aft of shaft alley. STERN TUBE Purpose of stern tube seal is the prevent seawater for penetrating into the ship. It also cool the shaft with seawater that is provided from the seawater service system. In case of seawater is leaking into the ship from the stern tube seal we can stop and lock the shaft and inflate the inflatable shaft seal using LP air, if we don’t have enough LP air pressure we also inflate the inflatable seal using CO2. BULKHEAD SEALS Purpose is the prevent flooding from AUX and MAIN spaces. They are located where the shaft penetrates through hull of spaces. CONTROLLABLE REVERSIBLE PITCH PROPELLER (CRP) The purpose of the system is to provides ahead and astern propulsion thrust by changing the pitch of the propeller blades without changing the direction of the propeller shaft rotation MAJOR COMPONENTS OF THE CRP SYSTEM HYDRAULIC OIL POWER MODULE (HOPM) The HOPM is consider the heat of the CRP system The HOPM divides the oil into control and power oil. Control oil goes to the OD Box and power goes to the hub. Control oil controls the power oil which the power oil do all the heavy work in the hub by moving the pitch of the blades GEAR/ ATTACHED PUMP Pump is attached to the MRG lower pinion outboard of both MRG’s, which when the MRG is in operation the attached pump will all be in operation. Can provide enough pressure when the system is operating above 120 gpm. ELECTRIC/ STANDBY PUMP  This pump is considered the standby pump. It’s the pump that will always be started when lighting of the CRP system. During underway operations the pump will start at 90 gpm and stop at 120 gpm. OIL DISTRUBUTION (OD) BOX The purpose of the OD Box is to control the position of the blades by positioning the valve rod, which in turn directs high-pressure hydraulic oil in the hub. HEAD TANK Provides static head pressure on the hub while the system is secure. Prevent seawater from leaking past the blade seals in the system. Both CRP system have its own head tank which is located the on the first deck in each engine room. EMERGENCY HYDRAULIC PUMP Only require which when the pitch cannot be set with the change over valves in the manual and auto position When the pump is install the pitch will be set at 130 percent this will require the change over valve be in the off position CO’s permission is required to set emergency pitch