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72-54-05
ALL ú ú N01 Page 408 ú Feb 18/02
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
ACCESSORY DRIVES - DESCRIPTION AND OPERATION
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1. General
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A. The accessory drives consist of a main gearbox and an angle gearbox. The main gearbox transmits power from the engine to the accessories mounted on the gearbox and provides specific speeds, torque, and mounting provisions required for the accessories to perform their various functions. The angle gearbox transmits power from the engine high pressure rotor (N2) to the main gearbox and from the starter on the main gearbox to the engine high pressure rotor (N2).
2. Main Gearbox (Fig. 1)
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A. The main gearbox is located at the bottom of the rear case of the high pressure compressor (HPC) and immediately in front of the diffuser case. It is attached to the HPC case utilizing a three point mounting system. Two points of this system are widely spaced, transverse-pin supported ball joints between the gearbox and the engine case at Flange K. The third support point consists of a vertical link with a single ball joint attachment on the gearbox driveshaft housing and two ball joint attachments on the HPC rear case. The ball joint attachments are free to move upon their support pins to allow for engine thermal growth without imposing loads on the gearbox mounting system.
B. The main gearbox consists of a cast aluminum housing incorporating a gear train and drive pads for the accessories. On the aft face of the main gearbox are drive pads for the integrated drive generator, starter, hydraulic pump, and the alternator for the electronic engine control (EEC). The breather (deoiler outlet) pad and mounting provisions for the oil tank are also located on the aft face. On the forward face are drive pads for the fuel pump/fuel metering unit and the housing for the main oil filter.
C. The power to drive the accessories is obtained from the high pressure compressor (HPC). A towershaft (radial driveshaft) in the intermediate case is geared to the front of the HPC shaft and drives through the bevel gears in the angle gearbox to the layshaft (horizontal driveshaft) and the main gearbox. General lubrication of the gears, bearings, and gearshaft splines is accomplished by use of oil jets and oil splash.
D. All accessory drive gearshafts are plug-in units. The pad seals are spring loaded carbon which bear on a polished carburized surface. With the exception of the fuel pump, all accessory mount pads incorporate a pad cavity drain boss. The fuel pump/fuel metering unit package has its cavity drain in the fuel pump housing.
3. Starter Drive (Fig. 1)
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A. The starter drive is located on the aft face of the main gearbox at the 5 o'clock position. The direction of rotation is counterclockwise. Starter drive coupling splines are not lubricated.
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72-60-00
ALL ú ú N01 Page 1 ú Feb 10/93
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
////////////////////////A / PW4000 SERIES /747-400 / ENGINES /MAINTENANCE MANUAL ////////////////////////
SEE A
INTERMEDIATE
CASE
RADIAL
DRIVESHAFT
MAIN GEARBOX ANGLE GEARBOX SEE B
SEE C
HORIZONTAL DRIVESHAFT
A L-A0532
Accessory DrivesFigure 1 (Sheet 1)
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