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The AZ2210040405 main shaft 1st gear is a genuine SINOTRUK HOWO component engineered to transmit maximum torque from the engine to the driveline during start‑up and low‑speed operation. As a critical element of the trusted Sinotruk howo parts family, this gear ensures smooth, reliable engagement of first gear in heavy‑duty transmissions. Manufactured from case‑hardened alloy steel (20MnCr5) with precision‑ground teeth, the AZ2210040405 gear is designed to withstand the extreme shock loads encountered in mining, construction, and long‑haul applications. Its robust construction guarantees long service life, reduced noise, and efficient power transfer, making it an essential component for maintaining driveline integrity in Howo trucks.
Main Shaft 1st Gear
Шестерня 1‑й передачи
Engranaje de 1ª velocidad
The AZ2210040405 gear is forged from 20MnCr5 alloy steel, then carburized and hardened to a case depth of 1.2‑1.8 mm with a surface hardness of 58‑62 HRC. This heat treatment provides exceptional resistance to wear, pitting, and fatigue under heavy loads. The core remains tough (30‑38 HRC) to absorb shock loads without fracturing. Teeth are profile‑ground to DIN 6 quality, ensuring smooth meshing and minimal noise. The gear features an optimized tooth profile that maximizes contact ratio and load‑sharing.
Each AZ2210040405 gear is 100% inspected for dimensional accuracy, including tooth lead and profile errors using CNC gear measuring centers. The bore is honed to a tight tolerance (H6) to ensure precise fit on the main shaft. The gear also features an integral synchronizer cone (where applicable) that is ground to a specific angle and surface finish for consistent shifting performance. This meticulous attention to detail guarantees reliable operation under the most demanding conditions.
The table below provides detailed technical data for the genuine SINOTRUK HOWO AZ2210040405 main shaft 1st gear. These specifications are essential for verifying compatibility and understanding its performance capabilities.
| Parameter | Specification | Details |
|---|---|---|
| OEM Part Number | AZ2210040405 | SINOTRUK HOWO Original Code |
| Product Name | Main Shaft 1st Gear | For HW19710 / HW19712 transmissions |
| Material | 20MnCr5 alloy steel (case‑hardened) | DIN 17210 |
| Number of Teeth | 41 | Helical, constant mesh |
| Module | 3.5 mm | Normal module |
| Helix Angle | 22° (right‑hand) | Optimized for quiet operation |
| Bore Diameter | 65 mm H6 | Precision ground |
| Face Width | 42 mm | Active tooth width |
| Overall Diameter | Approx. 175 mm | At tooth tip |
| Hardness (case) | 58‑62 HRC | Effective case depth 1.2‑1.8 mm |
| Tooth Quality | DIN 6 | Profile and lead tolerances |
| Synchronizer Cone | Integrated, angle 7° | Ground finish |
| Applicable Transmissions | HW19710, HW19712, HW25716 | Check main shaft spline |
| Included Components | Gear only | Synchronizer ring sold separately |
The AZ2210040405 main shaft 1st gear is used in Howo 9‑speed and 16‑speed manual transmissions, including the HW19710, HW19712, and HW25716 series. It is mounted on the main shaft and constantly meshes with the corresponding gear on the countershaft. When first gear is selected, the synchronizer sleeve locks this gear to the main shaft, transmitting engine torque to the driveline. This gear experiences the highest torque multiplication, making its strength and durability critical for vehicle launch and low‑speed maneuvering.
In heavy‑duty applications such as mining, logging, and on‑highway hauling, the 1st gear endures repeated shock loads during start‑stop operations. A worn or damaged AZ2210040405 gear can cause excessive noise, gear slippage, and even transmission failure. By using the genuine SINOTRUK HOWO gear, you ensure that the transmission maintains its original load capacity and shift quality, reducing downtime and operating costs. It is also compatible with various PTO configurations that draw power from the main shaft.
When replacing the 1st gear, always inspect the mating countershaft gear, bearings, and synchronizer components. Replace them if worn to ensure proper meshing and long service life. Use the correct assembly lubricant.
Correct installation of the AZ2210040405 gear is critical to ensure proper transmission function and long service life. Follow these steps:
Clean the main shaft thoroughly, removing any burrs or old Loctite. Inspect the shaft splines and bearing surfaces for wear. Replace if damaged. Have the new gear at room temperature.
Apply a thin film of assembly oil to the bore. Slide the gear onto the main shaft, ensuring it engages the splines fully. If an interference fit is specified, use a press and support the shaft to avoid bending.
Install the retaining rings and ensure the gear has the correct endfloat as per the service manual. Rotate the gear to verify smooth operation and no binding with adjacent components.
A worn 1st gear can cause shifting difficulties and transmission noise. Common signs that replacement is needed include:
If any of these symptoms are observed, immediate replacement with a genuine AZ2210040405 gear is recommended. Continuing to operate with a worn gear can lead to tooth breakage and catastrophic transmission damage.
The case‑hardened teeth and optimized geometry ensure reliable transmission of peak engine torque without fatigue or failure.
Precision manufacturing reduces wear on mating components, delaying the need for major overhauls and reducing total cost of ownership.
High‑precision tooth profiles and grinding minimize gear noise, improving driver comfort and reducing fatigue.
To maximize the service life of your AZ2210040405 main shaft 1st gear, follow these best practices:
By adhering to these guidelines, you ensure that the AZ2210040405 gear performs optimally throughout its intended service interval.
Aftermarket gears are often made from inferior steel with improper heat treatment, leading to rapid wear, pitting, and tooth breakage. They may have incorrect tooth geometry, causing noise, vibration, and premature failure of mating gears. The genuine AZ2210040405 is manufactured to the exact specifications of the original equipment, using certified 20MnCr5 steel and precise heat treatment. Each gear is tested for hardness, case depth, and dimensional accuracy, guaranteeing that it will perform exactly as the original part.
By choosing authentic SINOTRUK HOWO parts, you protect your investment and ensure your truck maintains its reliability and resale value. The Sinotruk howo parts catalog includes a full range of transmission and chassis components engineered for maximum durability. For fleet managers and owner‑operators who demand the best, the genuine AZ2210040405 is the only responsible choice.
The AZ2210040405 main shaft 1st gear is used across a wide range of Howo models: T7H, A7, and classic Howo‑7 series equipped with HW19710, HW19712, and HW25716 transmissions. It is specific to the first gear position; other gears have different part numbers. Always verify the tooth count and spline configuration with the service manual.
Each AZ2210040405 is individually wrapped in VCI paper to prevent rust. The packaging is clearly labelled with the OEM number and batch code. For bulk orders, gears are shipped in sealed cartons with foam inserts to avoid transit damage.
Production of the AZ2210040405 takes place in IATF 16949 certified facilities, using CNC hobbing, shaping, and grinding with in‑process gauging. Statistical process control ensures that dimensional variations are kept to a minimum, far exceeding the requirements of the original design. Every batch is accompanied by a material certificate and hardness test report, guaranteeing that the gears delivered are identical to those fitted on new Howo trucks at the factory.
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