CFM56-7B Engine Familiarization || Exercise Part-5

Part-5
CFM56-7B Engine General Familiarization (Engine for Boeing 737 Next Generation)

Purpose of Accessory Drive Module (Gear Box)
1) At engine start, the accessory drive system transmits external power from the engine air starter to drive the core engine.
2) When the engine is running, the accessory drive system extracts part of the core engine power and transmits it through a series of gearboxes and shafts in order to drive the engine and aircraft accessories.
3) For maintenance tasks, the core can be cranked manually through the Accessory Gearbox.

Identification
The accessory drive system is located at the 9 o'clock position and consists of the following components:
• Inlet Gearbox (IGB), that takes power from the HPC front shaft. (see chapter 2, Fan major module)
• Radial Drive Shaft (RDS), that transmits the power to the Transfer Gearbox.
• Transfer Gearbox (TGB), which redirects the torque.
• Horizontal Drive Shaft (HDS), that transmits power from the Transfer Gearbox to the

Accessory Gearbox.
• Accessory Gearbox (AGB), that supports and drives both engine and aircraft accessories.
Radial Drive Shaft (RDS)
The Radial Drive Shaft transmits power from the IGB to the TGB. The assembly is installed inside the fan frame No.10 strut at the 9 o'clock position.
It consists of:
• inner radial drive shaft and housing
• shaft mid-length bearing
• outer radial drive shaft and housing.
The inner and outer RDS are hollow and made of steel alloy.
One end of the outer RDS is internally splined and links with the externally splined end of the inner RDS.
Both ends of the inner and outer RDS assembly are externally splined and connect the IGB level gear with the TGB input level gear.
The shaft mid-length bearing provides proper centering of the RDS in its housing. Its inner race is mounted halfway up on the RDS and the outer race is part of the RDS housing.

Driven by the RDS, the Transfer Gearbox reduces rotational speed and redirects the torque from the IGB to the AGB, through the horizontal drive shaft.
It is secured under the fan frame module at the 9 o'clock position and consists of:
• Transfer gearbox housing
• Input bevel gear
• Horizontal bevel gear

Gearbox housing
The housing is a double-walled aluminium alloy casting, to improve oil scavenge.
The upper part of the housing consists of a bearing adapter assembly, that engages in the inner drive shaft housing in the fan frame shroud.
The TGB housing is attached to the fan frame shroud with four bolts. It has three oil nozzles for the lubrication of the level gears and bearings.

Input bevel gear
The upper part of the TGB houses the input bevel gear, its bearing housing, ball bearing and roller bearing. The input bevel gear has 31 teeth.
The bore of the bevel gear is splined at its upper end and engages with the outer radial drive shaft.
Sealing is provided by a seal ring installed internally in the input bevel gear bore.
An oil nozzle (not shown on diagram) supplies a jet of oil directly onto the bevel gear. Another oil nozzle supplies a jet of oil onto the roller bearing.
An oil distributor, installed inside the bevel gear and secured by the spirolock system, ensures oil distribution and axial retention of the outer RDS.

Horizontal bevel gear
The horizontal part of the TGB includes the transfer tube, the sleeve, the horizontal bevel gear, a ball bearing and a roller bearing.
The horizontal bevel gear has 32 teeth.
An oil nozzle directs 3 jets of oil into various parts of the horizontal bevel gear.
An oil distributor, installed in the bevel gear and attached by the spirolock system, permits oil distribution to the bearings.
The bore of the bevel gear is splined at its forward end and connects with the Horizontal Drive Shaft (HDS).
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Exercise Part-1
   • CFM56-7B Engine Familiarization || Exercis...  
Exercise Part-2
   • CFM56-7B Engine Familiarization || Exercis...  
Exercise Part-3
   • CFM56-7B Engine Familiarization || Exercis...  
Exercise Part-4
   • CFM56-7B Engine Familiarization || Exercis...  
Exercise Part-5
   • CFM56-7B Engine Familiarization || Exercis...  

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