DOC AIRBUS | AMM A320FACCESSORY GEARBOX ASSEMBLY - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
1. General
The Accessory Gearbox (AGB) assembly is mounted under the fan case at 6 o'clock. It consists of a gear train that reduces and increases the rotational speed to meet the specific drive requirements of each accessory. Some of the accessories are installed on the AGB through Quick Attach/Detach (QAD) rings.
The AGB consists of the following major assemblies:
** ON A/C NOT FOR ALL The Accessory Gearbox (AGB) assembly is mounted under the fan case at 6 o'clock. It consists of a gear train that reduces and increases the rotational speed to meet the specific drive requirements of each accessory. Some of the accessories are installed on the AGB through Quick Attach/Detach (QAD) rings.
AGB AssemblyThe AGB consists of the following major assemblies:
- Horizontal drive shaft,
- AGB housing,
- Gear train.
2. Description
A. Horizontal Drive Shaft Assembly
The horizontal drive shaft assembly provides power transmission between TGB and AGB. It includes the AGB-TGB coupling tube housing and the horizontal drive shaft.
The horizontal drive shaft assembly provides power transmission between TGB and AGB. It includes the AGB-TGB coupling tube housing and the horizontal drive shaft.
(1) The horizontal drive shaft is made of steel alloy. It is splined at both ends and drives the AGB gears through the handcranking driving gear.
(2) The horizontal drive shaft is retained in the AGB handcranking driving gear by a castellated nut in the gearshaft.
B. AGB Housing
(1) The AGB housing is an aluminum alloy casting. It is mounted under the fan case by 2 clevis mounts with shouldered bushings.
(2) The AGB housing front face has mounting pads for the following accessories and equipment.
(3) The AGB housing rear face connects with the horizontal drive shaft housing and has mounting pads for the following equipment :
(c) N2 speed sensor.
The N2 speed sensor is installed on the AGB; the air gap adjustment is obtained by laminated shims bolted on the AGB housing. Electrical signals are used by the FADEC and N2 cockpit indicator.
The N2 speed sensor is installed on the AGB; the air gap adjustment is obtained by laminated shims bolted on the AGB housing. Electrical signals are used by the FADEC and N2 cockpit indicator.
C. Gear Train
(1) The gear train is contained within the AGB housing and drives the accessories.
(2) Each gearshaft and its bearings and bearing support is a plug-in type assembly.
(3) Sealing past four of the AGB drive pads (IDG, hydraulic pump, starter and fuel pump) is provided by two (optional) configurations of carbon-contact seals. There are:
- Magnetic-type carbon seal,or
- Sealol-type carbon seal.
(a) Magnetic-type seal.
This seal consists of:
a non-magnetic seal housing which houses a magnetized mating ring with a polished face and a retaining ring.
a rotating seal, which has a carbon seal held in a rotating ring.
This seal configuration (detail K) can be used only for sealing past the drive pads which follow:
This seal consists of:
a non-magnetic seal housing which houses a magnetized mating ring with a polished face and a retaining ring.
a rotating seal, which has a carbon seal held in a rotating ring.
This seal configuration (detail K) can be used only for sealing past the drive pads which follow:
- Hydraulic pump
- Fuel pump
On the starter and IDG drive pads only, a different configuration of magnetic-type seal is used (detail B). This seal differs in that a thrust ring, which also acts as a thermal "exchanger", is added between the mating ring and the retaining ring.
(b) Sealol-type seal. (detail L)
The Sealol seal is made of a carbon packing and a rotating mating ring with a polished face. The rotating mating ring has 4 lugs that engage in 4 corresponding slots in the gearshaft on bearing. A housing containing a spring-loaded carbon seal ensures constant contact between the polished face of the rotating mating ring and the carbon seal element.
This seal configuration can be used for sealing past the drive pads wich follow:
IDG
Hydraulic pump
Starter
Fuel pump
The Sealol seal is made of a carbon packing and a rotating mating ring with a polished face. The rotating mating ring has 4 lugs that engage in 4 corresponding slots in the gearshaft on bearing. A housing containing a spring-loaded carbon seal ensures constant contact between the polished face of the rotating mating ring and the carbon seal element.
This seal configuration can be used for sealing past the drive pads wich follow:
IDG
Hydraulic pump
Starter
Fuel pump
D. Gear Train
(1) The gear train is contained within the AGB housing and drives the accessories.
(2) Each gear and its bearings and bearing support is a plug-in type assembly.
(3) Sealing is ensured by carbon seals.
(a) The magnetic seal consists of a non-magnetic seal housing, containing a magnetized mating ring, with a polished face and a carbon seal element held in the rotating seal. The constant magnetic force developed by the static ring onto the rotating ring maintains the carbon packing in contact with the polished face.
(b) The spring loaded seal consists of a rotating mating ring with a polished face. The rotating mating ring has 4 lugs that engage in 4 corresponding slots in the gearshaft on bearing. A housing containing a spring loaded carbon seal ensures constant contact between the polished face of the rotating mating ring and the carbon seal element.