Boxin · Hengzhen · Botrust
Precision Manufacturing・Powering the World
Countershaft Assembly
This is a countershaft assembly (transmission countershaft sub‑assembly) supplied as an original equipment component for Dongfeng Liuzhou Motor’s new‑energy vehicles. Made from 20CrMnTi alloy carburized steel, it serves as a core integrated part of the transmission’s powertrain, combining high strength, excellent wear resistance, and superior fatigue life. It is designed to meet the heavy‑load, cyclic operating conditions typical of new‑energy vehicles, ensuring stable and reliable power transmission.
- Product Description
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1. Basic Information and Positioning
- Target Audience : Dongfeng Liuzhou Automobile’s new-energy vehicles (pure electric and hybrid models) are equipped with a transmission secondary shaft drive system.
- Component Role : The core integrated component of the transmission’s countershaft, it combines the driving gear, the driven gear, and the shaft body into a single unit, enabling power splitting, speed reduction with torque multiplication, and torque transmission. As a critical assembly for achieving gear shifting and power distribution, it directly impacts the vehicle’s transmission efficiency and dynamic response.
- Supply Attribute : A specialized component designed to support Dongfeng Liuzhou Automobile, it matches the installation dimensions, fit tolerances, and performance requirements of the transmission in its new‑energy vehicle models. It can directly replace the original equipment, ensuring compatibility and consistency across the drivetrain.
2. Material and Process Characteristics
- Materials ：20CrMnTi Low-carbon alloy carburizing steel is a classic material for heavy-duty shaft and gear components.
- Heat treatment process: Employed Carburizing and quenching + low-temperature tempering Treatment: The hardness of critical components such as gear tooth surfaces and journal necks can reach HRC58-63 The core maintains high toughness while exhibiting excellent wear resistance, contact fatigue strength, and impact resistance, making it well-suited to the demanding operating conditions of new‑energy vehicles—high rotational speeds, high torque, and cyclic loading.
- Manufacturing Process: Employing precision hobbing and gear grinding, turning, grinding, and dynamic balancing correction, the gears achieve a precision grade of 7 or higher. The journal’s coaxiality and runout tolerances are tightly controlled, ensuring high‑precision meshing and fit with bearings and transmission gears, thereby reducing transmission noise and vibration while enhancing operational efficiency and service life.
3. Structural Features
- Overall structure : The integrated shaft‑gear assembly design integrates the central shaft, a helical drive gear, and an external-ring helical driven gear, representing a typical transmission countershaft subassembly configuration.
- Functional Segmentation ：
- Center shaft assembly: Serving as the core component for support and power transmission, the journal is precision-ground to accommodate bearings, providing shaft support and ensuring coaxial alignment. It meets the fit requirements of high-speed bearings, thereby reducing friction and wear.
- Center drive gear section: A helical gear segment located in the middle of the shaft, which meshes with the transmission’s driven gear to transmit power and convert rotational speed. The helical design ensures smooth engagement and low noise, enabling efficient power transmission.
- Outer-ring driven gear section: The outer-ring helical gear at the base of the assembly meshes with other driving gears, enabling power splitting and speed reduction with torque multiplication. Its tooth profile parameters are directly matched to the transmission’s gear ratio and load-carrying capacity, ensuring reliable high-torque transmission.
- Flange mounting structure: The gear end face is equipped with evenly spaced bolt holes for secure attachment to the gearbox housing or other components. The flange surface is precision‑machined to ensure coaxial alignment, thereby preventing vibration and axial movement during high‑speed operation.
4. Performance and Application Value
- Core Advantages : The 20CrMnTi material and carburizing‑quenching process enable this component to withstand the high torque, cyclic loads, and impact forces encountered in new‑energy vehicle transmissions, while resisting wear, pitting, and fracture. Precision‑machined gears and shafts ensure low noise and high‑efficiency operation, enhancing the vehicle’s ride smoothness and power performance.
- Compatible Scenarios The secondary shaft assembly for Dongfeng Liuzhou Automobile’s new‑energy vehicle transmissions can also be adapted to the transmission components of certain hybrid models, serving as a critical core component that ensures the stable operation of the vehicle’s power‑train system.
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