Main Transmission / Gearbox

Assembly

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Reduces engine speed and drives the main rotor, tail driveshaft and accessories.

Direct parts	11
Total parts	87
Used in	1 assembly
Class	Assembly

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Reduces engine speed and drives the main rotor, tail driveshaft and accessories. A full specification article for this item is being written. Meanwhile its bill of materials and connections are below.

Main Transmission / Gearbox parts and their functions

11 top-level parts · 87 parts in total · full bill of materials below

Main Transmission / Gearbox parts diagram: 1 planetary reduction stage, 2 helical gear pair, 3 freewheeling unit, 4 gearbox housing, 5 gearbox lubrication system, 6 ball bearing, 7 oil seal, 8 transmission mount, 9 chip detector, 10 torque & speed sensor, 11 hex bolt. 87 parts in 11 top-level items. — Main Transmission / Gearbox parts diagram. Numbers match the table below; each box is one top-level part or assembly with what it contains.

#	Part	Qty	What it does
1	Planetary Reduction Stage 4 parts	1×	Final epicyclic reduction stage to the rotor mast.
2	Helical Gear Pair	1×	input bevel reduction
3	Freewheeling Unit 2 parts	1×	Sprag clutch allowing rotor autorotation if the engine fails.
4	Gearbox Housing	1×	Magnesium/aluminium cast housing.
5	Gearbox Lubrication System 4 parts	1×	Oil pump, cooler and filter for the transmission.
6	Ball Bearing	6×	Deep-groove radial ball bearing.
7	Oil Seal	3×	Spring-loaded rotary lip seal that keeps lubricant inside a housing and dirt out where a shaft passes through, sized to DIN 3760.
8	Transmission Mount	4×	Strut or elastomeric mount transferring rotor loads into the cabin roof structure.
9	Chip Detector	3×	Magnetic plug that warns of metal particles in the gearbox oil.
10	Torque & Speed Sensor	2×	Sensor on the transmission input reporting torque and rotor speed.
11	Hex Bolt	48×	Flanged hex bolt, M8 to M24, used throughout the structure, covers and equipment mounts.

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Bill of materials for Main Transmission / Gearbox

11 top-level lines · 21 rows shown · 87 parts total · indented to 3 levels

#	Item / sub-assembly	Part no.	Qty/assy	Ext. qty	Parts	Type
1	Planetary Reduction Stage 4 parts	helicopter-planetary-stage	1×	1	12	assembly
1.1	Sun Gear	helicopter-sun-gear	1×	1	·	part
1.2	Planet Gear	helicopter-planet-gear	5×	5	·	part
1.3	Ring Gear (Annulus)	helicopter-ring-gear	1×	1	·	part
1.4	Ball Bearing	ball-bearing	5×	5	·	part
2	Helical Gear Pair	gear-pair	1×	1	·	part
3	Freewheeling Unit 2 parts	helicopter-freewheel-unit	1×	1	3	assembly
3.1	Sprag Clutch	helicopter-sprag-clutch	1×	1	·	part
3.2	Ball Bearing	ball-bearing	2×	2	·	part
4	Gearbox Housing	helicopter-gearbox-housing	1×	1	·	part
5	Gearbox Lubrication System 4 parts	helicopter-lube-system	1×	1	4	assembly
5.1	Oil Pump	helicopter-oil-pump	1×	1	·	part
5.2	Oil Cooler	helicopter-oil-cooler	1×	1	·	part
5.3	Oil Filter	helicopter-oil-filter	1×	1	·	part
5.4	O-Ring Set	oring-set	1×	1	·	part
6	Ball Bearing	ball-bearing	6×	6	·	part
7	Oil Seal	oil-seal	3×	3	·	part
8	Transmission Mount	helicopter-transmission-mount	4×	4	·	part
9	Chip Detector	helicopter-chip-detector	3×	3	·	part
10	Torque & Speed Sensor	helicopter-torque-sensor	2×	2	·	part
11	Hex Bolt	helicopter-hex-bolt	48×	48	·	part

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Where the main transmission / gearbox is used

1 product across 1 domain contain it, directly or inside a sub-assembly

Aerospace & Drones 1 Helicopter

Used in 1 assembly

Helicopter

Sourcing: possible vendors

Browse the supplier directory → Prices, MOQ, and lead times are algorithmic estimates, not quotes, and not claims about these companies. Company mappings are curated by keyword; est. price band $1–$300. How estimates work

Vendor	HQ	Specialty	MOQ	Lead time
🇮🇳Sona Comstar sonacomstar.com ↗	Gurugram, IN	EV driveline & motors	1,000 pcs	8–12 wks
🇨🇳Zhejiang Shuanghuan shdrive.cn ↗	Yuhuan, CN	Gears & driveline	1,000 pcs	8–12 wks
🇮🇳Bharat Gears bharatgears.com ↗	Mumbai, IN	Automotive gears	1,000 pcs	8–12 wks
🇮🇳ZF India zf.com ↗	Pune, IN	Driveline & chassis	1,000 pcs	8–12 wks
🇨🇳Hangzhou Advance advancegroup.cn ↗	Hangzhou, CN	Gearboxes	1,000 pcs	8–12 wks