【S4.0B】Upper Body Weldment

Every completed weldment undergoes a controlled stress-relief anneal at 580–620 °C for a minimum of two hours before any machining begins. This treatment reduces residual welding stresses by ≥ 75%, directly preventing the weld-toe fatigue cracks that cause non-treated weldments to fail in 400–800 hours of paddy tillage service. Furnace time-temperature charts are logged per batch and available to buyers on request.

Machining bearing bores before stress relief is a false economy — the subsequent heat treatment re-introduces the distortion the machining corrected. EVER-POWER sequences CNC boring after annealing, achieving H7 tolerance on all Ø50 mm seats and bore-to-bore spacing within ±0.3 mm across the full 820 mm weldment span. A CMM report for each unit accompanies the shipment documentation.

Internal gusset plates are laser-cut to profile at ±0.2 mm and interference-fit to their mating panel slots before tack welding. The interference fit acts as a self-jigging mechanism, holding components on position during tack sequences without needing the manual clamp adjustments that introduce cumulative positional error in standard fabrication shops.

Q345B's 345 MPa yield strength allows the main shell thickness to be 6 mm rather than the 8 mm required for an equivalent Q235B design — saving approximately 4 kg from the finished assembly. This weight reduction is meaningful on paddy tillers operating on terraced hillside fields where header mass directly affects tractor ballast requirements and stability margins.

Sa 2.5 shot-blast creates a clean anchor profile (Rz 40–70 µm). An epoxy zinc-rich primer at ≥ 60 µm DFT provides cathodic protection to exposed steel at damage sites. An electrostatic powder topcoat at ≥ 80 µm DFT adds UV resistance and mechanical durability. The combined system passes 500 hours of neutral salt-spray testing per ISO 9227.

Six M12 mounting holes are drilled and reamed to ISO-pitch spacing, ensuring direct bolt-on compatibility with the S4.0 header frame rails used on Kubota, Yanmar, and Dongfeng 4.0 m tiller platforms — the three highest-volume machines globally in the 4.0 m class — without frame modification or custom spacer fabrication.

Yield ≥ 345 MPa; tensile 470–630 MPa. Manganese content 1.0–1.6% provides solid-solution strengthening without significantly reducing weldability. Carbon equivalent (CE) is maintained below 0.45% in EVER-POWER's sourcing specification to ensure reliable heat-affected-zone toughness with CO₂-shielded MIG at ambient temperature — no preheat is required for sections up to 12 mm, a practical production-floor advantage.

AWS ER70S-6 equivalent deposited wire delivers tensile strength ≥ 500 MPa and Charpy impact toughness ≥ 47 J at −20 °C. This ensures that the weld metal does not become the weakest link in the load path during the low-temperature pre-dawn tillage operations common in China's northern wheat belt and India's Punjab during early spring planting campaigns.

At ≥ 60 µm DFT, the zinc-rich epoxy primer provides cathodic protection to bare steel at damage sites — the zinc particles sacrifice sacrificially, preventing base metal corrosion even when the topcoat is breached. This is the same protective mechanism as hot-dip galvanising applied as a coating, and it remains active at scratches and stone-chip sites where single-coat painted competing weldments begin to rust within a single wet season.

Safety Lock-Out & Header Prep

Disengage PTO, shut down engine, remove ignition key, and block the header securely on stands. Drain gearbox oil. Photograph all chain, cable, and bearing assemblies in their fitted positions before disassembly — reference photos eliminate ambiguity when reassembling unfamiliar sub-assemblies.

Disassemble Interfacing Parts

Remove bearings using a hydraulic puller — impact driving risks distortion of adjacent weldment structure. Tag each bearing with its bore position and measure radial play before discarding to determine whether bore wear was the primary failure driver or a secondary consequence.

Inspect Frame Rail Face

Check the frame rail mating face for twist or bow using a precision straight-edge. Deviation exceeding 1.0 mm must be corrected by pressing or machining — a new weldment bolted to a distorted rail will carry that distortion into its bore geometry regardless of its own manufacturing precision.

Offer Up & Align Weldment

With a second person supporting the 32 kg weldment, engage all six M12 bolts finger-tight before introducing any preload. Confirm the weldment seats flush to the rail face without rocking. Any gap at this stage indicates a face flatness issue that must be resolved before torquing.

Torque Bolts & Press Bearings

Torque the six M12 Grade 10.9 bolts to 115 N·m in three diagonal stages. Press new bearings using a hydraulic arbour press at controlled force. Verify each bearing outer race is fully seated to its shoulder using a feeler gauge — any gap ≥ 0.05 mm requires the pressing operation to be repeated.

Reassemble, Fill & Run-Verify

Reinstall shafts, seals, and ancillary components. Fill the gearbox to specified level with fresh SAE 90 GL-4 oil. Engage PTO at low speed for 5 minutes and observe for oil weeps, bearing noise, or vibration before returning to full operational speed. Re-torque mounting bolts after 50 hours.

• Visual inspection of all weld toes for surface cracks, especially at bearing-boss fillets
• Check all six mounting bolts are fully seated — feel for movement under load
• Inspect coating at stone-impact zones; touch-up with cold zinc spray as needed
• Listen for any bearing-noise change during first 5 minutes of PTO engagement

• MT or dye-penetrant test on weld toes if vibration anomalies have been noted
• Measure bore diameters with an internal gauge; replace bearings if ovality ≥ 0.05 mm
• Re-torque all mounting bolts to 115 N·m after initial settling period
• Clean drain ports; apply rust-inhibitor compound inside accessible cavities
• Check lower body mating face for fretting marks indicating loose joint preload

• Full external wash; remove all soil from cavities and recesses
• Apply penetrating rust inhibitor to bolt-head contact faces and open bore ends
• Photograph and document any new crack indications; compare against previous season
• Drain any water from interior cavities before winter storage
• Touch-up all bare-metal patches; confirm coating integrity at all weld toes

China's domestic aftermarket for 4.0 m-class header structural weldments is the world's largest by unit volume. EVER-POWER materials are sourced against GB/T 1591 certificates. The ISO 9001:2015 facility satisfies the documentation requirements of China's agricultural machinery purchase subsidy programme, which mandates certified supply chains for subsidised equipment. Steel laser-cutting scrap is 100% recycled through contracted mills.

EU Machinery Directive 2006/42/EC requires structural components of powered agricultural machinery to meet minimum design and manufacturing standards. EVER-POWER supplies welding procedure qualification records (PQR), material declarations, and dimensional drawings sufficient to support CE technical file preparation. Italy, France, and Germany are the largest EU buyers of this product category.

South and Southeast Asia represent the fastest-growing export segment for S4.0B weldments, driven by mechanisation programmes expanding large-format tiller deployment into paddy regions previously served only by two-wheel tractors. BIS (India) and TCVN (Vietnam) import documentation requirements for HS Code 8432.80 are bundled into EVER-POWER's standard export documentation package.

Powder coating uses zero-VOC formulations. Shot-blast wastewater is processed through a closed sediment-filter loop meeting China GB 8978 standard. The product's 5–7 season service life reduces material throughput per unit of agricultural output by replacing shorter-lived alternatives less frequently — stress-relieved weldments generate significantly less secondary scrap than non-treated alternatives requiring early replacement.

The co-operative was replacing header body weldments from a local fabrication shop on an 18-month cycle driven by bore wear and bearing failures. After switching eight of their fourteen tillers to EVER-POWER S4.0B weldments in Spring 2022, they tracked bearing replacement frequency across the full fleet for two seasons. The S4.0B units required zero unplanned bearing changes; the local-shop units required nine mid-season changes across the remaining six machines. The co-operative converted the remaining six units by Q1 2024.

A major Po Valley machinery rebuilder specialising in rotary tiller header overhauls adopted EVER-POWER S4.0B weldments as their standard replacement specification in 2022. The workshop manager cited the CE-compatible documentation package and furnace stress-relief records as the deciding factors — both are non-optional for work performed under Italian regional farm modernisation grant programmes. Zero warranty claims on weldment bores were recorded across two full seasons.

A Vietnamese cooperative operating a continuous three-crop annual calendar in the upper Mekong Delta had been destroying non-stress-relieved aftermarket weldments through weld-toe cracking within a single wet season. Three S4.0B weldments introduced in the 2022 wet season were still in service with no crack indications at the 2024 dry-season inspection, having accumulated approximately 900 working hours per unit — three times the service life of the predecessor sourcing.

Complete the S4.0 Header System

Vibrating Screen Assembly & Auxiliary Auger Chain Cover

The S4.0B upper body weldment, the vibrating screen assembly, and the auxiliary auger chain cover form the core structural and protective components of the EVER-POWER S4.0 header system. Sourcing all three from EVER-POWER delivers matched dimensional compatibility and consolidated compliance documentation.

Quality Documentation Available

Mill test certs · Furnace stress-relief records · Welding PQR · CMM reports · Salt-spray test certificates — on request for every batch.

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