Tractor Assembly Line Plan (SKD)

A wheeled tractor is built from seven functional modules—engine, driveline, running gear, steering, braking, hydraulics and electrics. Main-line assembly follows a one-piece flow: wash and kit parts, marry engine to gearbox, drop axles, fill fluids, cold-turn and hot-test the powertrain, align wheels, calibrate PTO, then mount cab and hood. Critical control points are locating datums, metered oil fill and on-line roller tests. For overseas markets the SKD concept splits the job: China pre-assembles and tests the engine-gearbox-rear-axle module, seals hydraulics and fits quick connectors, then packs frame sections, tyres and cab into one 40 HC container. Abroad only ten bolt-on operations and quick couplers are needed, giving sub-two-hour tractor completion while keeping high-skill tests and torque data traceable in China.

Tractor Assembly Line Plan下载

I. Complete-machine structure

  1. Power source
    1.1 Diesel engine assembly
    1.2 Five sub-systems: air-intake, exhaust, cooling, lubrication, fuel
    1.3 Three-point rubber mounts + front bracket, vibration-isolated and ready for engines of different makers
  2. Driveline
    2.1 Main clutch (dry or wet dual-stage) → gearbox (8+4 or 12+12 speeds) → central drive → differential → final reduction
    2.2 PTO shaft (540 / 1 000 rpm dual-speed)
    2.3 Front-drive axle (optional): electro-hydraulic engagement, cardan shaft
  3. Running gear
    3.1 Front axle: pivoting “inverse-A” structure, flange or sliding half-shaft, manual or stepless track adjustment
    3.2 Rear axle: one-piece housing, built-in planetary final reduction; hub bolted to cast-spider flange, reversible for track change
    3.3 Tyres: agricultural R1 pattern, 6–12 PR; dual-wheel capable
  4. Steering
    4.1 Front-wheel (<120 hp) or articulated frame (>140 hp)
    4.2 Full-hydraulic orbital + priority valve, rim effort ≤15 N·m
  5. Braking
    5.1 Wet multi-disc inside final drives; parking brake spring-applied/hydraulic-released
  6. Implement hydraulics
    6.1 Three-point hitch Cat. I/II, lift capacity ≥10 kN
    6.2 2–4 quick-coupler remote valves, rated flow 30–50 L min⁻¹
    6.3 Front hitch + front PTO (option) for self-propelled maize headers
  7. Electrics & HVAC
    7.1 12 V / 24 V negative ground, alternator 55–90 A
    7.2 CAN-Bus dashboard, DTC read-out
    7.3 Cab: ROPS/FOPS certified, HVAC roof unit

II. Assembly process (main-line level)

Cycle time 8–15 min for 3 000–15 000 units yr⁻¹. Numbers in brackets refer to the Chinese original.

  1. Parts wash → scan → kitting
    1.1 Al/Fe parts high-pressure spray + dry, particle weight ≤20 mg pc⁻¹
    1.2 QR code binds to MES, mistake-proof
  2. Engine–gearbox marriage (AGV)
    2.1 Engine horizontal, crankshaft dowel aligns with clutch housing
    2.2 Clutch release travel pre-set 25–30 mm, high-temp grease applied
    2.3 Diagonal two-pass tightening, 90–110 N·m, wireless nut-runner ±3 %
  3. Frame–axle drop (KBK hoist + quick-change fixture)
    3.1 Semi-frame bolted to main gearbox, engine-mount face flatness ≤0.3 mm
    3.2 Front-axle swing-stop sealed to keep out mud
  4. Wheel–tyre sub-line
    4.1 Rim-to-spider bolts 220 N·m, thread-locker applied
    4.2 Auto nitrogen fill, pressure 0.18–0.22 MPa
  5. Hydraulic seal test
    5.1 Static 1.5 × rated pressure, 3 min, leakage ≤2 drops min⁻¹
    5.2 PTO oil seal pressed with guide sleeve to avoid lip cut
  6. Wiring & grounding
    6.1 Loom in corrugated tube, grommets at bulkheads; ground ≤0.1 Ω
    6.2 Dashboard flashed on-line, CAN self-check OK
  7. Oil/coolant metered fill
    7.1 Engine 15 L±0.2 L, gearbox 40 L±0.3 L, rear axle 25 L±0.2 L
    7.2 Vacuum fill ≤90 s including bubble removal
  8. Cold turning & hot test
    8.1 Cold: motorised 800 rpm ×10 min, oil pressure ≥0.15 MPa
    8.2 Hot: 50 % load ×30 min, no blue/white smoke, coolant 85–95 °C
  9. 4-wheel alignment & PTO speed calibration
    9.1 Front toe-in 0–3 mm, rear track difference ≤5 mm
    9.2 PTO 540 rpm ±10 rpm, 1 000 rpm ±15 rpm
  10. Cab, hood, plastics
    10.1 ROPS bolts 271 Loctite, 300 N·m
    10.2 Body gap ≤1.5 mm, flush difference ≤1 mm
  11. Roll-out check (roller brake + lighting)
    11.1 Roller test 5 km h⁻¹, slip ≤8 %
    11.2 Braking distance ≤0.5 m (5 km h⁻¹), L/R force diff ≤5 %
  12. Power-wash → dry → decals → final QC → warehouse

III. SKD (Semi-Knocked-Down) line design

Goal: split “full assembly” into two stages—core modules pre-built & tested in China, overseas CKD/SKD plant only bolts, hoses & wires—cutting tariff and local investment.

  1. SKD split rules
    1.1 Modules complete: engine-gearbox-rear-axle already aligned, hydraulics sealed, electrics with quick connectors
    1.2 Packing volume: 4 sets per 40 HC, ≤64 m³
    1.3 Local content abroad: tyres, cab, hood, battery, plastics only; target ≤2 h tractor⁻¹
  2. China pre-assembly (extra “module test”)
    2.1 Engine-gearbox-rear-axle on pre-assembly rig: cold turning, PTO speed set, hydraulics 1.5 × proof
    2.2 Frame in front & rear sections: dowels + quick bolts, field join ≤10 min
    2.3 All couplers changed to quick types:
    – Hydraulics ISO 5675 flat-face with dust cap
    – Electrics Deutsch 12/24 way, key-coded
    – Coolant self-sealing quick coupler, spill ≤1 mL
  3. Packing & containerisation
    3.1 Engine-gearbox module on 120×100 cm steel pallet, VCI bag + desiccant, humidity card ≤30 % RH
    3.2 Tyres stood upright, fixed to container wall
    3.3 Cab foam + wooden frame, glass anti-shatter film
    3.4 1 % spare-parts kit (fuses, bulbs, O-rings) & bilingual bolt list
  4. Overseas SKD plant layout (example 3 000 units yr⁻¹)
    4.1 Line: double-wing, 12 stations, Heavy-duty underground plate-chain assembly line, cycle 18 min
    4.2 Equipment:
    – 4×2 t jib cranes (cab & ballast)
    – 18 wireless nut-runners, torque data to MES
    – 1 vacuum oil filler, 5 min finish
    4.3 Manpower: 18 station⁻¹, two shifts, 80 % local skill
    4.4 Key stations:
    ① Module index & drop (front & rear frame)
    ② Quick-connect hydraulic/electric re-check (scan proof)
    ③ Tyre/ballast/cab fit
    ④ Roller-brake-light re-test (same spec as main plant)
  5. Quality & traceability
    5.1 Each SKD module gets QR code with engine & gearbox serial, hydraulic report
    5.2 Overseas plant scans code, auto-downloads torque programme & parameters
    5.3 Critical bolts (engine mounts, ROPS) torque uploaded to China server real-time; alarm if out-of-spec

IV. Take-away

  1. Structurally divide the tractor into seven systems; each becomes a pre-tested module for SKD packing.
  2. Assembly sequence “inside-out, hard-soft, static-dynamic”, with three control points: locating datum, metered fill, on-line test.
  3. SKD essence: “pre-set in China, quick-connect abroad”, locking high-skill jobs (cold turning, hydraulic proof, PTO calibration) at home while giving tariff benefits and easy local start-up.

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