Drive System Flashcards
General
Consists of:
- Engine transmissions
- Combining transmission
- Forward transmission
- Aft transmission
Primary function is to transmit engine output to rotor system. Secondary function is to drive AC generators, hydraulic pumps, transmission oil pumps, tach gen, and transmission oil cooler fan
Engine shafts to c box, 7 sync shafts from c box to forward transmission, 2 sync shaft from c box to aft transmission, vert shaft from aft transmission to aft rotor head, fan drive shaft, cooling fan, and rotor brake near c box
Each transmission has a separate primary and auxiliary lube system with sensors to detect temp, pressure, and metallic chips
Engine Drive Shafting
Connects output of engine to input pinion of c box
Each shaft made of aluminum tubing with each end connected with a flex coupling to compensate for minor misalignment
Both shafts are serial numbered and dynamically balanced
Aft Synch Drive Shafting
Connects aft output of c box to input pinion of aft transmission
2 shafts connecting with Thomas couplings and mounted to fuselage with lord mounts
Aft sync shafting is supported by a single bearing
Forward Synch Drive Shafting
7 shafts connecting forward output of c box to input pinion of forward transmission
Forward 6 Synch shafts are identical and interchangeable, 7th shaft is unique in that it doesn’t have a bearing and support assembly attached to it
All 7 shafts are interconnected with Thomas couplings and aluminum adaptors mounted to each end
Fan Drive Shafting
Transmits torque from aft transmission to transmission oil cooling fan
Extends diagonally up and forward from aft transmission at approximately a 45* angle
Aft Vertical Drive Shaft
Extends upward from aft transmission through aft pylon to aft rotor head. Shaft is splined to aft transmission output and is secured to airframe via thrust bearing
Each end of shaft is made of steel and pinned to carbon fiber center section
Center of rotor head is splined to aft vert shaft on the top
Aft Vert Shaft Thrust Bearing
Connects aft vert shaft with aft pylon structure
Distributes lift force from aft rotor system to airframe instead of aft transmission
Bearing assembly is pressure lubricated with oil from aft transmission lube system, and the oil return line contains a screen and chip detector
Transmission Oil Temp Indicating System
Consists of 5 temp bulbs, selector switch, and gauge
Each temp sensor from its corresponding input transistor is applied to logic circuit which is controlled by the selector switch. When switch is set to TEST, the output of the logic circuit is 0 volts, resulting in a 0 degree indication
When selector is set to SCAN the logic circuit compares the 5 temp signals and selects the highest reading
Transmission Oil Temp Warning System
5 thermal switches warn pilot of overtemp condition when transmission oil temp increases above 140*C, illuminating common XMSN OIL HOT. The switch is located in line just prior to their respective coolers
2 thermal switches monitor oil temp in sumps of No. 1 and 2 engine transmissions. They closes on temp above 207*C and light their associated annunciator (ENG # XMSN HOT)
Transmission Oil Pressure Indicating System
Consists of 5 transmission pressure transducers, switch assemblies, selector switch, and indicator dial
Logic circuit controlled by selector switch indicates pressure of transmission selected, and when set to SCAN it compares 5 pressure signals and selects the lowest pressure
Transmission Oil Pressure Warning System
5 identical oil pressure switches provide warning for underpressure condition. Contacts close on decreasing oil pressure below 18psig
When oil pressure drops below 18psig the associated pressure switch illuminates XMSN OIL PRESS light
Engine Transmissions
Mounted on front of engine, takes N2 output power from quill shaft and changes its direction 90 degrees to go into c box
Sprag clutch on output shaft permits freewheeling if Nr exceeds N2
Engine is lubricated from main and auxiliary oil pumps located in c box. Scavenge pump located on c box returns oil to its reservoir
Combining Transmission
Combines torque from both engine transmissions and changes its direction 90 degrees, distributing the power to output shafts to drive forward and aft transmissions.
3 section oil tank with common filler port provides primary and auxiliary lubrication for c box and engine transmissions. Accessory drive spur gear on forward output shaft provides drive for 6 element pump for 3 main oil pumps and 3 scavenge oil pumps. Auxiliary lube pumps for c box and engine transmissions are punted on same accessory drive and are visible on exterior of c box
Caliber assembly for rotor brake is on rear cover of c box, with calipers working against disc mounted on splined adapter to aft output shaft
Engine and Combining Transmission Primary Lubrication
3 compartment tank on top of c box supplies oil to engine transmissions and c box. Tank is approx 10 gallons
Within c box main oil pumps for each transmission provide pressure to their respective engine, passing oil through an oil filter, 2 oil coolers, and in line jet protection screen before passing onto lube jets. Scavenge oil pump is provided for each transmission to return oil to reservoir
Chip detectors located in transmission sump with burn off system, to prevent minute metallic particles. These illuminate XMSN CHIP DET and ENG CHIP DET lights, and to determine which transmission has chips the maintenance panel in aft fuselage area must be consulted
Engine/C Box Reservoir
1 big tank with 2 walls inside tank divide it into 3 separate chambers. Common filler and breather aperture is on top.
At the base of each compartment is combined temp bulb and overlay switch
Engine/C Box Pressure Pumps
3 pressure pump are housed within c box, and are driven from common shaft and each draws oil from its own section of reservoir
Extreme pressure is released by a relief valve for protection of system
Engine/C Box Filter
Filter mounted on rear side of c box, fitted to its respective pump outlet
Bypass indicator pops out to indicate blockage in element and oil will bypass filter to the system
Engine/C Box Oil Coolers
2 coolers attached to rear pylon and each is made of 3 separate sections. Each pump delivers oil to section of one then the other cooler
Bypass valve attached to each cooler inlet acts as thermal control valve and opens at temps below approx 70*C. Valve also acts as safety bypass should cooler becomes blocked
Engine/C Box Jet Protection Screens
Screens stop contaminants from block feed jets when filters bypass
Sounds like a last chance oil filter
Engine/C Box Pressure Switch
Causes XMSN OIL PRESS to come on if system falls below 18psig
115VAC and CB is on No. 2 PDP
Engine/C Box Pressure Transducer
Fitted to pressure line of each oil system, converts pressure into electrical signals, power supply is 115VAC and CB is on No. 2 PDP
Engine/C Box Chip Detector
Fitted to base of c box and engine nose boxes, illuminate XMSN CHIP DET or ENG CHIP DET light and trips mx panel magnetic indicator
Engine/C Box Temp Bulb
Temp transducers located in associated portion of 3 section oil tank
Engine/C Box Thermal Temp Switch
Located in primary pressure line just before the inlet of oil cooler
Close when temps reach above 140*C, this completes a ground circuit and illuminates XMSN OIL HOT
Engine transmissions have thermal switches fitted to base of each engine transmission case. They cause ENG 1/2 XMSN HOT light to come on if temp exceeds 207*C
Engine/C Box Debris Screen
Located in each ENGINE transmission SCAVENGE return line
Bolted to inlet return of respective scavenge pump, when metal particles get trapped by screens they activate SCREEN ENG XMSN LEFT/RIGHT magnetic indicator on mx panel and simultaneously light ENG 1/2 CHIP DET light
Engine/C Box Scavenge Pump
One scavenge pump for each gearbox lube system, driven by same shaft as pressure pumps, and return oil back to respective section of 3 compartment reservoir
Engine/C Box Aux Lubrication
Independent from main lube system provided for each engine and c box transmission, is running anytime the primary system is functioning. It has its own pump, filter, pump relief valve, low pressure switch, and lube jets
Both primary and aux lube systems designed to pump return oil into aux sump. The sumps are located within each of 3 main sumps in reservoir. Oil fills aux sump first and then overflows into main sump
Aux lube system provides essential lubrication fro critical bearings and gears for up to TWO HOURS
Aux oil does NOT flow through the oil coolers and there is no provision for cooling oil
Eng/C Box Aux Pump
3 separate pumps, mounted on forward side of c box, driven by common shaft in c box
Each pump draws oil from respective aux sump
Eng/C Box Aux Oil Pressure Switch
Operates when system pressure falls below 10 psi, causes shared XMSN AUX PRESS light to come on and respective aux lube pressure magnetic indicator on mx panel
Mx panel must be consulted to determine which aux system is at fault
Forward Transmission
Gearbox built with forward rotor shaft INCLINED at 9 degree angle, internally has spiral bevel pinion gear, ring gear, and 2 stages of planetary gears
Accessory drive gears in transmission drive main and aux oil pump and main rotor tach. Main oil pump is fitted to forward underside of gearbox and is accessible externally. It draws oil from sump, pressurizes it, and passes oil to oil cooler in aft pylon area and onto main bear surfaces and gears of forward transmission
Aux pump is within forward transmission housing, forward of rotor head shaft.
Main rotor tach is attached to outer face of main oil pump, consists of small 3 phase AC generator, frequency of AC current is measured and represented as rotor speed percent
Chip detector in aux sump of gearbox illuminate XMSN CHIP DET and must be identified by transmission mx panel
Forward Transmission Main Lube System
Comprised of:
- Wet type sump
- Main pump protective screen
- Pressure pump
- Pump relief valve
- Filter
- Oil cooler
Oil from sump goes through screen and into inlet of pump, pump pushes oil through filter, oil cooler, and jet protection screen to transmission inlet
Oil then goes to lubricators and jets within transmission, spraying oil on transmission bearing and rotating gears
Forward Transmission Main Sump
Wet sump at base of gearbox, integral funnel shaped casting in center of base forms aux system sump to which all oil is returned
Oil is directed to aux sump, which fills first, then overflows to main sump area
16 us quarts
Forward Transmission Main Pressure Pump
Mounted on forward bottom side of transmission casing, pump is driven by accessory drive shaft also driving rotor tach
Forward Transmission Cooler
Lowest radiator cooler on aft pylon is for forward transmission
When oil temp is above approx 70*C a bypass valve closes and directs oil through the cooler
Bypass valve also acts as a safety relief should cooler becomes blocked
Forward Transmission Pressure Transducer
Fitted to RH side of each rotor gearbox, converts oil pressure to electric signals to power instrumentation in cockpit
Power supply is 115VAC and CB is on No. 2 PDP
Forward Transmission Pressure Switch
Fitted downstream of each pressure transducer, causes XMSN OIL PRESS light to come on at 18psi with diminishing pressure
CB is on No. 2 PDP
Forward Transmission Chip Detector
Fitted to aux sump of forward transmission, illuminates XMSN CHIP DET and simultaneously triggers magnetic indicator on transmission mx panel in ramp area
Power supply is 28vdc from emergency bus system and CB is No. 1 PDP
Forward Transmission Aux Lube System
Aux lube system provides lube to limited section of gearbox and is complete and separate system from main lube system
Contained entirely within the forward transmission housing
Consist of:
- Aux sump
- Sump screen
- Aux pump
- Filter
- Low oil pressure switch
Oil is totally self contained and not allowed to flow to the oil cooler
Forward Transmission Aux Oil Pump
Pump is driven by internal gear trains and independent of main oil drive
Pump draws oil from aux sump and pressurizes it to 1.25gpm at 80psig
Pressure relief valve opens at 90psig
Forward Transmission Aux Oil Filter
Located externally on left side of lower transmission housing, filters oil from aux pump to lube jets
Forward Transmission Aux Low Oil Pressure Switch
Located beside aux oil filter on left lower side of transmission housing
Illuminates XMSN AUX PRESS if pressure falls below 10psi, will also simultaneously operate magnetic indicator on mx panel
Aft Transmission
Transmits torque from aft synch shaft to aft vert drive shaft, rotor shaft is tilted forward 4*, consists of spiral bevel gear, ring gear, and 2 stage of planetary gears for reduction
Contains 2 accessory drive gears:
- First one driven by input shaft and drives oil cooler blower shaft and oil scavenge pump. Blower shaft provides drive for oil cooler fan and via an accessory pad, the backup flight control hydraulic pump and emergency generator
- Second accessory gear drives AGB section with a sprag clutch. AGB drives lube pump, 2 flight control hydraulic pumps, 2 AC generators, utility hydraulic pump, 2 generator scavenge pumps, and AGB motor
Transmission has main and aux system:
- Main system is is pressure system with wet sump, temp bulb, chip detector, pump protection screen, drain valve, pressure switch. Main system also lubes thrust gear on aft vert shaft. Thrust bearing return oil return line contains chip detector and oil filter
- Aux system consists of integral pump, pump protection screen, filter, and pressure switch.
Aft Transmission Main Lubrication
Consists of:
- Wet type sump
- Pump protection screen
- Pressure pump
- Relief valve
- Filter
- Oil cooler
Oil is drawn from sump through protection screen and into inlet of pump. Pump pressurizes system and oil goes through filter, cooler, and strainer to transmission inlet port. Oil supplied through external piping goes to aft vert shaft thrust bearing. Passages in transmission deliver oil to lubricators and jets, which spray oil onto gears and bearings
Pressurized oil also lubricates accessory drives at rear of transmission. External pressure line provides oil to the oil cooled generators, and scavenge pump returns oil to sump.
Flexible tube at bottom of accessory drive case allows oil from accessory gears and bearing to drain into sump
Scavenge pump in fan drive housing is driven by fan drive shaft, pump returns oil, which collects in forward part of transmission during nose low attitudes, to main sump
Mains sump holds 22.5 us quarts. Components on sump include:
- Oil temp bulb on forward sump wall
- Chip detector on bottom of aux sump
- Magnetic plug
- Drain valve at aft end of sump
Aft Transmission Drive Shaft Lubrication
Aft drive shaft secured to aft transmission deck by cast housing and thrust bearing. Thrust bearing is lubricated with oil from main lube line
Return oil passes filter and chip detector, which activates SHAFT magnetic indicator on mx panel and XMSN CHIP DET on master caution panel
If aft transmission lube system fails, thrust bearing would NOT be lubricated
Aft Transmission Aux Lube System
Identical to forward transmission aux lube system
Transmission/Engine Chip Detector Burn-Off System
Installed to prevent minute metallic particles from activating warning system
Operates automatically and consists of zapper module (located at right side of aircraft) and 8 chip detectors
Module contains capacitors, circuitry, and electro mechanical four digit counter for each chip detector
When particles build up and bridge magnetic contacts of chip detector, capacitor is discharged to burn off particles and counter is advanced one digit
Larger particles cannot be burned off and will activate chip detector and indicators. Switch is provided to disable the system. When disabled, warning light located on zapper module will come on indicating system is inop and annoying chip detector indications could result
