Propulsion/ Aux Turbines & Reduction Gears/ Propellers Flashcards
what type of turbine blading is used for installation in circumferential groves?
tee-rot blading
outside dovetail type turbine is used with what type of entry?
circumferential entry
how is axial-entry type turbine blading secured to the rotor wheel (disk)?
by a platform interlock, pin or key
end play cold thrust bearing clearance is defined as?
the distance the thrust collar can be moved between the forward and aft thrust bearing faces without applying appreciable load to either face
typical end play with the engine cold is?
.008 - .014 inch
the term total float clearance refers to what?
the axial clearance taken with the thrust bearing shoes removed
when taking bearing depth micrometer readings, bridge gage readings and the taking of leads the lube oil system should be secured when?
24 hours prior to taking the readings
what material are oil deflectors manufactured from?
aluminum or bronze
what NSTM covers general information on SSTG turbines?
NSTM 231
what two types of impulse turbines used exclusively for auxiliary use?
curtis-rateau or straight rateau
the lube oil cooler should be bypassed on an operating auxiliary turbine until the discharge oil temperature reads what?
100 degrees F
if a metal edge filter is installed in the oil line on an auxiliary turbine, the filter handle shall be turned how many ties per watch?
at least once per watch
when starting SSTG’s what is the minimum allowable lube oil temperature?
60 degrees F
after starting an SSTG, at what vacuum is the generator brought up to speed?
15 inches
what is the major difference critical RPMs on an SSTG compared to a auxiliary turbine?
critical SSTG RPMs are achieved at 20-25 percent below normal operating speed, auxiliary turbine critical RPM’s is achieved above normal operating pressure
temporary distortion of the SSTG rotor after the numerous start/stop episodes is known what?
a bowed motor
what must the lube oil temperature be on a SSTG prior to bringing it up to operating speed?
100 degrees F
SSTG gland sealing steam pressure has a range of what?
1/2 - 2 psi
speed limiting governors installed on auxiliary turbines are deigned to limit maximum speed to what percentage of designed speed?
110 percent
on an SSTG turbine, what action must be taken if clearance between the nozzle diaphragm and the adjacent row of blades is outside the limits prescribed by the manufacturer?
adjusts the position of the rotor by changing the filler piece in the thrust bearing
SSTGs are fitted with what type of governor?
constant speed
on an SSTG, what protects the turbine casing from excessive pressure?
back pressure trip
what is installed on non condensing turbines to protect the turbine casing from excessive pressure?
combination exhaust relieve valves
the combination exhaust relief valve is set to lift at what range?
2 - 3 psi above exhaust line pressure
what is installed upstream in the steam line of the governor to protect an SSTG turbine from debris?
steam strainer
who is the approving authority for turbine casing and rotor weld repairs
NAVSEA
how is a damaged auxiliary turbine blade removed when it is not feasible or the situation does not permit reblading?
the damaged blade and the blade diametrically opposite must be cut off at the junction of the vane portion and the root and the root checked for balance if practical
turbine failure must be reported to whom?
NAVSEA
how are failed turbine parts documented?
word description and photographs
turbine blading erosion is usually limited to what area?
the blade or nose tips of the last few rows of low pressure turbine
when steam is being admitted to the propulsion turbine the rotor should not remain idle for more than how many minutes?
5 minutes
when warning a propulsion turbine, the turbine should be rotated with steam at what interval?
every 2 - 3 minutes
what is the quickest means to determine any change in the relief position of the propulsion turbine rotor caused by bearing wear?
depth gauge micrometer
what maintains the axial position of the propulsion turbine rotor?
thrust bearings
what maintains the radial position of the propulsion turbine rotor?
journal bearings
how is the propulsion turbine bearing wear determined?
by measuring the outside of the diameter of the rotor journal and the inside diameter of the bearing to determine actual oil clearances. the difference between the old and the new clearance readings will be the amount of bearing wear.
what type of gauge is used to measure the clearance between the high pressure and low pressure turbine?
taper gauge
when replacing a propulsion turbine journal bearing, the rotor must be lifted vertically to what maximum height, in order to ease the removing of the lower half of the bearing ?
.005 inch
if damaged labyrinth packing cannot be replaced due to operation commitments, how can the packing be repaired?
by use of a chisel bar and. hand chisel to straighten the teeth
what action must be taken if you suspect internal turbine damage that warrants lifting the turbine?
a request to lift is made to NAVSEA
whenever a propulsion turbine casing joint is opened for any reason, a final contact check is required by taking red and blue check of the made up joint, what is the required contact for non pumping groove joints?
75 percent contact over the entire joint plus 1/2 inch minimum continuous contact and inside the bolts and across each pressure section
when is the work considered complete on a propulsion turbine that was opened for inspection and repair?
after satisfactory dock and post repair trials
how many types of propulsion turbines are used in the Navy?
five
on an SSTg, what is used to seal the nozzle diaphragm and the rotor to prevent steam leakage?
labyrinth packing
what is the function of the staff packing on an SSTG?
to prevent leakage of steam from an ingress of air into the turbines
to obtain maximum effective sealing of the labyrinth packing the rip width of packing should be maintained within what parameter?
.010 inch
what NSTM contains information on the repair and care of labyrinth packing?
NSTM 231
what is the most common slant that is used on turbine casing joints?
copalite
what is the most common cause of turbine blade failure?
resonant blade vibration
what method of measurement is used to determine radial seal wear?
crown thickness method
prior to conducting thrust bearing measurements on the main engine, the turbine must be at ambient temperature with the throttles shut for what duration?
24 hours
steam turbine rotos and bearings are classified as what level of repairable part?
depot level
when a defective turbine part is received from the navy stock system, what report must be filed?
the quality deficiency report (QDR), SF 364
what is the most commonly used propulsion turbine?
Type II-A (straight through unit)
a constant security watch must be maintained when conducting turbine nozzle clearances, the watch must be who?
a responsible E-5 or above
turbine lagging pads must be verified as non asbestos by using what guidance?
NSTM 635
what advantage does a locked train reduction gear have over other designs?
has the capability of transmitting higher powers, lower sensitivity to misalignments and ease of misalignments
main reduction gears are inspected by NAVSEA at what interval?
every ten years or when conditions warrant
who is authorized to extend the ten year reduction gear inspection?
by TYCOM when operating conditions indicate that a longer interval between inspection is desirable
detailed information on reduction gear security can be found in what NSTM?
NSTM 241
what are two types of reduction gears used in auxiliary type ship?
worm and helical
what type of reduction gear would you expect to find inane auxiliary type ship?
tandem articulated double reduction with one or more power inputs
define transverse diametrical pitch of a reduction gear?
the ratio of the number of teeth of the number of inches of the pitch diameter
when the ship is within 1 hour of port or anchorage and maintaining standard speed the reduction gear lube oil temperature is lowered to what?
10-15 degrees F or 100 degree minimum
while import, how often must the secured reduction gear be rotated with lubrication?
weekly
during the weekly lubrication of the reduction gear, the propeller shaft should be jacked how many turns?
one and quarter ( 1 1/4) turns
what inspection is accomplished bi weekly on a secured reduction gears?
visual inspection
inspection plates, connections, fittings or covers, which permit access to the reduction gear casing, must not be removed without whose authority?
engineer officer
what NSTM has general reduction gear information?
NSTM 241
reduction gears having a 125 k-factor or less must have a tooth contact of what, to be considered satisfactory?
80 percent
what determines the blacklash on a pair of double helical gears?
longitudinal movement
a standard SSTg reduction gear has a gear ratio of what?
8 to 1
after installing new bearings on an SSTG reduction gear, what is the required gear tooth contact?
90 percent contact
what is the required reduction gear tooth contact for an SSTG with helical gear?
80 percent of the face width
where is the pre close out inspection of the main reduction gear logged?
in the engineering log
who conducts the pre close out inspection of the main reduction gear?
engineer officer
what is the requirement for the installation of locks on main reduction gear panels and plates?
locks are required on all apnea and plates with 1 or fewer bolts and nuts
who performs the ten year reduction gear inspection?
naval shipyard or contracts shipyard
all reduction gears are fitted with oil spray nozzles oil onto the gears, if these nozzles become clogged when corrective actions must be taken?
secure the gears and clean the affected oil spray nozzles. scary nozzles are required to be kept open during any gear operation
main engine turbine bearings are measured for what at what normal interval?
annually
when must a constant be re-estalished on a main engine bearing?
upon bearing replacement
where are bearing measurements recorded and by whom?
by the work center supervisor and logged in a permanent bearing book
define the term blacklash?
the amount by which the width of a tooth spaces exceed the tooth thickness of the engaging tooth at the operating pitch circle
define the term K-factor when associated with reduction gears
an index that indicates the intensity of tooth from the standpoint of tooth surface durability
what two processes are used to Harden gear elements?
carburizing and nitriding
what is the most common bearing found in MRG’s?
sleeve type
how is a dental type coupling lubricated?
by a continuous flow of oil to the coupling teeth through the adjacent bearing feed line or spray nozzle
the electric motor driven turning gear to what on the MRG?
1st reduction gear
what is used to remove airborne oil fog emanating from the MRG vent airstream before it can be discharged into the machinery space?
the electrostatic (vent fog) precipitator
what is located after the air inlet within the bottom of the vent fog precipitator?
a flame arrestor assembly
what is the only acceptable criteria for an operating MRG lube oil sample?
clear and bright
when does torsional critical speed normally occur in an operating MRG?
at low speed
after securing the MRG, the main lube oil pump is secured IAW what criteria?
once the lube oil temperature is within 10 degrees F of engine room ambient temrpature
when the ship is docked and the gears are rotated by the turning gear, throttles are close and secured with chain and lock. who is responsible for the key to that lock?
the engineer officer
when a dehumidifier is installed during an extended MRG lay-up, the dehumidifier must maintain what relative humidity within the MRG casing?
less than 35 percent relative humidity
access covers or plates installed on MRG attached with less than 12 nuts and bolts have what percentage secured with a lockable cover?
25 percent
who authorizes any dismantling or removal of any MRG casing or its access openings, piping, matched fixtures, or fittings?
engineer officer
custody of keys for all security locks are the responsibility of whom?
OEM personnel
at what frequency is the main shaft inflatable seal tested?
semi-annual or IAW PMS
what medium is used to inflate the main shaft seal under normal conditions?
CO2
what NSTM covers general information on all types of propellers?
NSTM 245
the area most likely to cavitate on a propeller is?
the suction side of the outer radii and areas near the leading edge
a propeller that vibrate at natural frequency is characterized by what term?
singing
propellers that have been in operation for more than five years must be inspected by what technique?
liquid penetrant
upon completion of a propeller visual inspection report, the report is submitted to whom?
type commander or ship’s CO
what type of proper cleaning uses non siliceous material?
hone blasting
who approves all procedures for repairing non bronze propellers?
NAVSEA
waterborne propeller visual inspections are conducted at what frequency?
every six months
