The Threshing Machine Body Assembly is a complex welded housing located in the core processing area of the combine harvester. It is the foundational platform that carries the threshing drum, mounts the concave, “guides in and out” the material flow, and provides support and tensioning points for the internal drive of the machine. Let’s take a tracked harvester as an example to break down the parts it contains and the role it plays in the harvester!
What Does the Threshing Machine Body Assembly Do?
| Function | Description |
| Supports the Threshing Drum | Serves as the mounting base for the drum main shaft and bearing housings, withstanding the massive centrifugal force and alternating loads generated by the high-speed rotation of the drum. |
| Mounts the Concave | Provides precise mounting slots and support surfaces for the concave, ensuring that the threshing clearance between the drum and the concave meets design standards. |
| Material Flow Guidance | Equipped with internally welded deflector plates, curtains, and other structures to guide the crop smoothly into the threshing zone and discharge straw smoothly from the rear. |
| Drive Support and Tensioning | Features multiple bearing housing mounting points and tensioning wheel brackets on the inside and outside of the housing, providing support points for the drive belts/chains of the threshing drum. |
What Parts Are in the Threshing Machine Body Assembly?
The combine harvester threshing machine assembly consists of hundreds of parts. By function, it can be divided into four major systems: core skeleton, threshing and separation core, high-frequency wear areas, and guard and safety systems.
| Module | Part Name | Quantity |
| I. Main Housing & Material Guidance System | Threshing machine body assembly | 1 |
| Machine body component | 1 | |
| Miscellaneous guide plate seaming | 1 | |
| Wind deflector seaming | 1 | |
| Air deflector seaming (II) | 1 | |
| Convex plate assembly | 1 | |
| Feeding arc plate assemblies | 1 | |
| Feeding arc plate assemblies | 1 | |
| Right feeding plate seaming | 1 | |
| Left feeding plate seaming | 1 | |
| Wind adjusting plate (II) | 2 | |
| Left wind adjusting plate seaming | 1 | |
| Right wind adjusting plate seaming | 1 | |
| Convex plate | 1 | |
| Front diagonal bevor seaming | 1 | |
| Connecting plate | 1 | |
| Bulk head heightened plate | 1 | |
| II. Sealing & Leak Prevention System | Sealing pressplate | 1 |
| Feeding port sealing plate | 1 | |
| Sealing plate | 1 | |
| Pressplate | 1 | |
| Reinforced panel seaming | 1 | |
| Retaining curtain | 1 | |
| Pressplate seaming | 1 | |
| Backing plate | 2 | |
| Sponge strip 15x15x360 | 4 | |
| Sponge strip 25x15x560 | 4 | |
| III. Concave Assembly | Concave plate assembly | 1 |
| Front concave plate seaming | 1 | |
| Rear concave plate seaming | 2 | |
| Connecting plate | 4 | |
| Connecting plate assemblies | 4 | |
| IV. Tensioning & Drive Adjustment Mechanism | Belt bracket seaming | 1 |
| Tensioning wheel assemble | 1 | |
| Bearing 6204 | 2 | |
| Tensioning spring | 1 | |
| Belt tightening assemble | 1 | |
| Bearing 6205 | 1 | |
| Bearing 6005 | 1 | |
| Belt wheel | 1 | |
| Belt pulley assembly | 1 | |
| Reversing pulley | 2 | |
| Tensioning pulley assemble 2 | 1 | |
| Tensioning wheel combination | 1 | |
| Deep groove ball bearing 6202-2RS | 1 | |
| Tension spring | 1 | |
| Tensioning wheel assemble | 1 | |
| Bearing 6302 | 1 | |
| Backstop | 1 | |
| Bearing 6004 | 2 | |
| Tensioning wheel combination | 1 | |
| V. Guards & Safety Support Parts | Shield support assembly | 1 |
| Front shield upper support seaming | 2 | |
| Front shield lower support seaming | 4 | |
| Support seaming | 1 | |
| Support seaming | 1 | |
| Support seaming | 2 | |
| Left box heap shield lower support… | 1 | |
| Left side-hole cover plate | 1 |
Main Housing & Material Guidance System
Welded from left and right side panels, front and rear crossbeams, and the bottom plate. This is the foundation of the entire threshing chamber.
- Main Housing: Machine body component.
- Guidance & Leak Prevention: Miscellaneous guide plate seaming, wind deflector seaming, convex plate, left/right feeding plate seaming.
- Sealing & Curtains: Feeding port sealing plate, bottom retaining curtain, sealing pressplate, rubber plates, and multiple sponge strips (e.g., 15x15x360, used for grain leakage prevention and vibration damping).
Concave Assembly
The arc-shaped separation sieve wrapped under the drum directly determines the threshing and separation effect.
- Core Parts: harvester concave plate assembly, including front concave plate seaming and rear concave plate seaming, secured inside the machine body via connecting plates and fasteners.
Tensioning & Drive Adjustment Mechanism
The belt drive of the threshing drum relies heavily on precise tensioning force. Multiple complex tensioning mechanisms are arranged on the outside of the housing.
- Belt Tensioning Bracket & Tensioning Wheel Assembly: Internally includes deep groove ball bearings 6204 (2 pcs), bearing 6005 (1 pc), bearing 6202-2RS (1 pc), and bearing 6302 (1 pc). Equipped with straight grease nipples and dust caps, requiring regular greasing.
- Reversing Pulley & Belt Pulley: The belt pulley assembly includes reversing pulleys (2 pcs), used for reversing and anti-blocking under special working conditions.
- Adjustment Components: Adjustment bolts, tension springs (e.g., RGV3301060187), support arm weldments, etc.
Guards & Safety System
The exterior of the housing is equipped with upper/lower shield support bases and various shield weldments to protect the high-speed rotating harvester pulleys and tensioning wheels, preventing personnel entanglement and straw wrapping.
- Inspection ports such as the left-side hole cover plate are provided on the housing for daily observation and quick clearing of blockages.
Common Faults and Replacement Signals
| Fault Symptom | Possible Cause | Components to Check |
| Housing weld cracks, abnormal noise | Long-term vibration, unrelieved welding stress, overload | Joints between side panels and crossbeams, around bearing housings |
| Incomplete threshing or sudden spike in broken grain rate | Worn or deformed concave mounting positions causing clearance changes | Concave adjustment slots, limit blocks, machine body deformation |
| Severe grain leakage | Damaged bottom sealing curtain, aging rubber plates, detached sponge strips | Machine body bottom, feeder house connection port, retaining curtains |
| Unstable drum rotation, high vibration | Worn bearing housing mounting holes, damaged tension wheel bearings (e.g., 6204) | Left/right side panel bearing seats, tensioning wheel assemblies |
| Belt slipping, burning | Tension spring fatigue, worn belt pulleys (reversing pulleys) | Tensioning mechanism, belt pulley assembly |
How to Choose the Right Threshing Machine Body Assembly Replacement Parts?
Match by OEM Assembly Number: The body dimensions, bearing hole positions, and concave slot positions are completely different across machine models. Please be sure to provide the exact model (e.g., Lovol RG50) and assembly number (e.g., RGV3201320000K).
Focus on Welding and Machining Processes: Choose products that use robotic/CO2 shielded welding and undergo stress relief treatment after welding to prevent future deformation.
Distinguish Between Assembly and Individual Parts: You can purchase individual parts like side panels, curtains, and tensioning wheels separately; however, if the body is severely deformed or has large areas of weld cracking, it is recommended to directly replace the complete welded assembly.
Maikeyier is a supplier with the dual identity of “in-house forging factory + complete machine parts supply chain.” For large welded components such as the threshing machine body housing, concave, and drum, we work with high-quality manufacturing partner factories to produce them strictly according to OEM drawings and Maikeyier quality control standards. We currently provide agricultural parts for the four major brands: Kubota, Yanmar, Lovol, and FMWorld. Please provide the exact machine model and part number, and we will quote you within 24 hours.