# Guide to Technical Specifications for the Assembly of Agricultural Machinery Parts

Technical Specification Guide for the Assembly of Agricultural Machinery Parts I. Key Technical Points for the Assembly of Agricultural Machinery Parts (I) Assembly Specifications for Parts with Chamfers Valve guide assembly — Intake guide chamfer angle: 30°±1°; exhaust guide chamfer angle: 45°±1°; correct orientation: the chamfered end faces the valve head. Consequences of incorrect assembly: intake and exhaust resistance increases by 15-20%, and engine power decreases by 8-10%. Oil pump outer rotor assembly — Standard assembly: the chamfered end faces the pump housing. Inspection indicators: oil supply pressure 0.25-0.35 MPa; oil supply volume ≥40 L/min. Impact of reverse installation: oil pressure decreases by 30%, and the risk of lubrication system failure increases. Drive gear assembly — Correct installation: the 30° chamfered end faces the drive wheel. Torque requirements: tightening torque 80-100 N·m; axial clearance 0.05-0.10 mm. Consequences of error: bearing life is shortened by more than 50%. (II) Bearing and Bushing Assembly Technology Oil hole alignment principle — Alignment accuracy requirement: ±0.5 mm. Lubrication interval: rocker arm bushing every 50 hours; main bearing shell every 100 hours. Sealed bearing installation — Dust cover orientation: clutch bearing faces the driven plate; hub bearing faces outward. Grease filling amount: 8-10 g for 60204; 12-15 g for 60206. (III) Assembly Specifications for Shaft-Type Components Governor gear shaft — Fit tolerance: shaft-hole fit H7/g6; radial runout ≤0.03 mm. Installation orientation: the end without a hole is pressed into the body, with the oil hole facing downward. Rocker shaft seat — Correct installation: the slit faces downward. Clearance standards: valve clearance 0.20-0.25 mm; push rod clearance 0.05-0.10 mm. (IV) Key Assembly Points for Major Assemblies Cylinder assembly — Cylinder gasket installation: the wrapped edge faces the cylinder head. Tightening sequence: from the center outward; torque gradient: 20-30-40 N·m. Injector clamp — Correct orientation: the flat surface faces outward. Tightening requirements: tighten in a cross pattern; final torque 25 N·m. Clutch driven plate — Installation standard: the boss faces away from the installation side; end runout ≤0.5 mm. Adjustment parameters: release clearance 2-3 mm; pedal free travel 30-40 mm. (V) Steering System Assembly Tie rod end — Thread identification: right-hand thread is used for the left-side joint; left-hand thread is used for the right-side joint. Toe-in adjustment: standard value 4-8 mm; parallelism ≤1 mm/m. (VI) Gearbox Assembly Specifications Shift fork shaft positioning — High-speed shift fork shaft: groove spacing 10±0.1 mm, installation position at the rearmost end. Low-speed shift fork shaft: groove spacing 8±0.1 mm, installation position in the middle. Range shift fork shaft: installation position at the foremost end, with the large end of the groove facing right. (VII) Crankshaft Seal Assembly Model 4125 diesel engine oil seal — Upper housing features: with oil return hole, bolt holes without threads; lower housing features: with internal threads, no oil return hole. Assembly points: bolts are threaded in from bottom to top; sealant thickness 0.5 mm. (VIII) Valve Cover Assembly Installation standard — Seal gasket replacement interval: every major overhaul; tightening sequence: gradually tighten diagonally; torque requirement: 8-10 N·m. II. Assembly Quality Inspection Standards Geometric accuracy inspection — Coaxiality ≤0.05 mm; perpendicularity ≤0.03 mm/m. Functional testing — Pressure test: 1.5 times working pressure; running-in test: 30 minutes no-load. Sealability inspection — Airtightness test: 0.3 MPa held for 5 minutes; leakage detection: fluorescent leak detection. III. Common Assembly Errors and Prevention | Error Type | Consequence | Preventive Measure | | Part installed backward | System failure | Mark installation orientation | | Oil hole misalignment | Poor lubrication | Use positioning pins | | Insufficient torque | Loosening and oil leakage | Use a torque wrench | | Improper cleaning | Early wear | Ultrasonic cleaning before assembly | IV. Recommended Professional Assembly Tools Precision measuring tools: digital display torque wrench (accuracy ±1%); laser alignment instrument. Specialized assembly equipment: bearing heater (0-200°C); hydraulic press-fitting equipment. Auxiliary materials: Loctite sealant; molybdenum disulfide grease. Through standardized assembly processes and strict quality control, optimal performance of agricultural machinery parts can be ensured and equipment service life extended. It is recommended to establish assembly process cards, record key parameters, and achieve traceability of the assembly process.