CX501KB Series
TRAINING GAS TURBINES
EPICYCLIC SPEED REDUCTION
GEARS
MLN BLOCK 405, ALGERIA
OPERATOR TRAINING
CX501KB Series
TRAINING GAS TURBINES
SECTIONAL VIEW : EPICYCLIC GEAR
Total weight 2,847kg. Top cover 234kg
GEAR SECTION 3 PAGE 1-2
CX501KB Series
TRAINING GAS TURBINES
SPECIFICATION
ASG 34 "Star" type epicyclic gear manufactured by Allen Gears of Pershore,
England.
Designed to transmit 6650kW
Gear overhung from the alternator end frame
Auxiliary drive for the main lubrication pump and starter motor
Speed reduction from 14,571rpm to 1,500rpm
Sunwheel 21 teeth; (turbine speed) 14,571rpm
Starwheels (3) 91 teeth; 3362.6rpm
Annulus 204 teeth; 1500rpm
Pump take off wheel (annulus) 127 teeth; 1500rpm
Pump idler 51 teeth; 3735rpm
Pump gear 59 teeth; 3230rpm
Starter idler 56 teeth; 3402rpm
starter gear 41 teeth; 4646rpm
CX501KB Series
TRAINING GAS TURBINES
starwheel 3362rpm
gearcase
EPICYCLIC gearbox axial
GEARS vibration monitor
annulus
pto shaft speed 1500rpm
monitor
pto shaft
alternator
turbine
coupling
sunwheel drain
temperature
monitor
sunwheel 14571rpm
fixed star wheel carrier
gearcase
drain
GEAR SECTION 3 PAGE 3-4
CX501KB Series
TRAINING GAS TURBINES
PRINCIPLE OF OPERATION
Central sunwheel is connected to the high speed shaft from the turbine.
Sunwheel drives the Star Wheels in the opposite direction.
Star Wheels are pinned into the star carrier which is bolted between the high
speed and low speed casings.
The Annulus fits over the Star Carrier and meshes with the Star Wheels.
The rotating Annulus drives the alternator via the Low Speed Coupling
CX501KB Series
TRAINING GAS TURBINES
EPICYCLIC SPEED REDUCTION GEAR
STAR WHEELS
ROTATING ABOUT ROTATING ANNULUS
OWN SPINDLES
FIXED STAR
CARRIER
PTO SHAFT
CONNECTION
ALTERNATOR
ROTATING
CONNECTION
SUN WHEEL
GEAR SECTION 3 PAGE 5-6
SUNWHEEL
GAS TURBINES
STARWHEEL
SUNWHEEL
BEARING
PTO SHAFT
COUPLING
CX501KB Series
TRAINING GAS TURBINES
ANNULUS AND STAR WHEELS TURN IN THE OPPOSITE
DIRECTION TO THE SUNWHEEL
annulus starwheels (3)
204 teeth 91 teeth
1500rpm 3362.6 rpm
pump take
off wheel sunwheel
127 teeth 21 teeth
1500rpm 14571rpm
pump idler starter idler
51 teeth 56teeth
3735rpm 3402rpm
pump gear starter gear
59 teeth 41 teeth
3230rpm 4646rpm
GEAR SECTION 3 PAGE 7-8
CX501KB Series
TRAINING GAS TURBINES
LUBRICATION
The main oil pump supplies cooled and filtered oil from the common
engine/gearbox/alternator supply to the gearset at 2.07 bar.
Internal pipework supplies pressurised oil to lubricate the starter drive and
pump bearings, and the oil inlet plate.
An annular groove in the inlet plate distributes oil to the centres of the star
wheel spindles and the sun wheel.
Oil is sprayed onto the gear surfaces through tappings in the spindles.
Oil is drained from the gear internals directly to the common lube oil tank
CX501KB Series
TRAINING GAS TURBINES
Internal Lubrication Epicyclic Gear
oil inlet plate
internal oil pipe
to main journal fixed starwheel
bearing pinion white metal
bearing surfaces
external oil pipe pressure
to coupling
flange fed from inlet plate
sunwheel oil nozzle
assembly pressure
sunwheel drain fed from pinions -
temperature spray to sunwheel
monitor teeth and then to
starwheels and
external oil pipes annulus. Oil mist
to pump and within casing
starter gears and
provides additional
bearings
lubrication
supply pressure gravity drain to
2.07bar 206l/min oil tank
GEAR SECTION 3 PAGE 9-10
CX501KB Series
TRAINING GAS TURBINES
AUXILIARY DRIVES
Both the starter and oil pump are mounted on the high speed casing of the
gearbox and operate through shafts and idler gears acting on the low speed
(alternator coupling flange) gear ring .
The main oil pump shaft assembly and idler gear are mounted on roller and
ball bearings and are geared to turn at 3230rpm at maximum speed.
This speed provides oil at a flow rate of 353litres per minute at 7 bar.
A priming pump is provided for starting.
CX501KB Series
TRAINING GAS TURBINES
AUXILIARY DRIVES
COUPLING FLANGE
ANNULUS RING GEAR
ALTERNATOR
COUPLING
TURBINE PTO (LOW SPEED)
(HIGH SPEED)
OIL PUMP
DRIVE
STARTER IDLER GEARS
DRIVE attached to the Low Speed
Casing
GEAR SECTION 3 PAGE 11-12
GAS TURBINES
COUPLING FLANGE
PUMP IDLER RING GEAR STARTER IDLER
GEAR GEAR
CX501KB Series
TRAINING GAS TURBINES
AUXILIARY DRIVES
The starter motor drives through a clutch mounted within the starter shaft
assembly, and idler gears acting on the low speed (alternator coupling
flange) gear ring.
Torque is transmitted from the starter through the clutch during the start
sequence until the turbine is self sustaining at 10,500rpm - a shaft speed of
approx. 3,500rpm.
The start system is switched off and the clutch disengages.
At maximum speed the clutch is disengaged and the starter stationary whilst
the shaft spins at 4646rpm.
GEAR SECTION 3 PAGE 13-14
CX501KB Series
TRAINING GAS TURBINES
GEARBOX RELATED SHUTDOWNS
GEARBOX OIL PRESSURE LOW - Lube oil pressure < 1.38 bar g whilst
running at > 13000rpm. Check main and standby lube pumps; Oil
pressure regulator fault or system leaks.
GEARBOX VIBRATION HIGH - Monitors gearbox axial vibration. Any
sudden change in vibration levels should be reported to Centrax.
SUNWHEEL DRAIN TEMPERATURE HIGH - Lube oil temperature >85°C.
Monitors temperature of oil in the sump of the sunwheel bearing on the
gearbox input shaft. Normally associated with temporary mis-alignment
on start up. Unload the bearing and splines by taking the turbine off and
then back on load
CX501KB Series
TRAINING GAS TURBINES
PROTECTION
General Lube oil system protection including filtration and cooling and
temperature and pressure monitoring by the control system apply to the
gearbox (this will be discussed in the Lube Oil section)
A dedicated RTD mounted in the gearbox drain provides an Alarm (Sunwheel
Drain Temperature High) if the lube oil temperature exceeds 85°C.
Gearbox vibration is monitored by an accelerometer mounted on the top of
the high speed gear casing to give an Alarm (Gearbox Vibration High) if
vibration exceeds 5mm/sec and Shutdown at 7mm/sec.
GEAR SECTION 3 PAGE 15-16
