Engineering gears

Core Structural Features

1. Integrated Structure Design

• The assembly integrates the planetary gear, needle roller bearing, and bushing into a single unit. The planetary gear outer ring has an involute tooth profile, with a needle roller bearing press-fitted into the inner bore. The central hole aligns with the planetary carrier pin, with a rotational clearance ≤0.03 mm to ensure smooth planetary rotation and self-rotation.

• The gear end face is designed with a flange/sealing cap (as shown in the circular end cover in the image), preventing needle roller bearings from falling out and blocking dirt ingress. The protection level reaches IP65, suitable for harsh construction site conditions.

• Typically, small module and wide tooth designs are used, with a tooth width coefficient of 0.8–1.2, increasing tooth contact area and load capacity. A single planetary gear can withstand radial loads of several tons.

2. Materials and Manufacturing Processes

• The planetary gear is made of 20CrNiMo low-carbon alloy carburizing steel, carburized and quenched, achieving surface hardness of HRC58–62 and core hardness of HRC30–40, balancing impact resistance and wear resistance. Needle roller bearings use GCr15 bearing steel with HRC62–64 hardness, providing excellent wear resistance.

• Tooth profiles are manufactured using hobbing and grinding, achieving GB/T 10095 grade 6 or higher, with tooth surface roughness Ra ≤1.6 μm. The bearing-to-gear bore interference fit is precision-ground after assembly to ensure coaxiality ≤0.02 mm.

• Surface treatment includes blackening with anti-rust oil, and end face sealing caps are zinc-passivated to resist mud, water, and dust corrosion. Rust protection exceeds 6 months.

3. Assembly and Compatibility Features

• The planetary gear assembly is hinged to the planetary carrier via a pin, with pin ends fixed by retaining rings. This allows easy assembly and maintenance on-site. A single planetary gear stage typically includes 3–6 planetary gears, distributing load and reducing stress on individual gears.

• Designed for meshing with an internal ring gear and sun gear in a planetary transmission layout, with backlash controlled at 0.1–0.3 mm. The assembly operates reliably across -40°C to 80°C, meeting construction requirements in various climates.

Main Functions and Applications

1. Power Transmission and Torque Conversion

• As a core component of planetary transmission, the assembly transmits power from the sun gear to the internal ring gear. Multiple planetary gears achieve load distribution. A single-stage planetary gear ratio can reach 1:20–1:50, converting high-speed, low-torque input from the engine or motor into low-speed, high-torque output for actuators. For instance, in excavator travel mechanisms, this enables heavy-duty power output for climbing or digging operations.

• Needle roller bearings significantly reduce friction between the planetary gear and carrier pin, improving transmission efficiency to over 95%, reducing energy loss and lowering fuel/electricity consumption.

2. Adaptation to Harsh Working Conditions

• The multi-planet load-sharing design absorbs impact loads at construction sites, preventing single gear overload and tooth breakage. The sealed structure prevents dirt from entering the bearings, avoiding needle roller jamming and extending mean time between failures (MTBF > 5000 hours).

• Fatigue-resistant tooth profiles withstand long-term alternating loads. Fillet-strengthened gear roots increase bending fatigue strength by 30%, suitable for frequent direction changes and start-stop operations of construction machinery.

3. Optimizing Overall Machine Performance

• The compact structure reduces planetary gearbox size, fitting into tight spaces of construction machinery. The lightweight, integrated design lowers unsprung mass, improving machine maneuverability. For example, in wheel loaders, steering response can improve by 15%.

Product selling points & advantages

Good hardenability and machinability

High surface hardness

Tooth modifcation

Good gear mesh performance,low meshing impact,low meshing noise

High load capacity

Tooth width load equally distributed

High resistance to wear

High precision grade

Stability in drivingHigh accuracy of meshing movement

Long operating life

High transmission effciency

Constant transmission ratio

Small vibration

The company's main products are high-precision involute gears and gear shafts. We specialize in the manufacturing of spur gears, helical gears, herringbone gears, external splines, internal splines, cycloidal wheels, pin gear shells, new energy automobile gears and other gear products .

Products are widely used in the wind power industry: wind turbine planetary gears, sun gears, high-speed gears, ring gears, etc., rail locomotive industry, shipbuilding industry, petroleum industry, aviation gears, compressor gears, RV reducer cycloid wheels and pin gear shells, Coal mining machinery and reducer industry, lifting machinery and many other industries.

Our customers include CRRC, Yuanjing, Italian Cappi Gear, Double Ring Transmission, Guomao Reducer, NGC, Hitachi Compressor, etc.

The types of material are: forge piece, dieforge piece,castings,welded piece,steel rods and so on. The various heat treatment methods applied todifferent raw materials are : carburizing and quenching, sub-zero treatment ,gas nitriding,ionitriding,induction quenching, overallquenching,hardening and tempering and so on.

For heavy duty and high speed gears, materials containing Ni such as 17CrNiMo6.18CrNiM07-6.18Cr2Ni4WA are adopted. This type of materialhas high core toughness and surface hardenss with strong bending resistance and torque resistance after approperiate carburizing and quenching.High hardness surafce and high accuracy grinding makes the tooth surface become highly wear resistant.

We can process gear of precison grade as per diferent national standards: such as DlN 3-6 grade,AGMA10-13 grade,1s0 3-6 grade, jls 0-2 grade GB 3~6 grtade , etc.

We can also make modifcations to various tooth profles and helixes according to the diferent applications as wellas customer's requirements . Themain modifcation methods aplied to gear grinding machine with form wheel are: crowned shape ,crowned shape with slope,K shape, tooth widthasymmetric modifcation. Tooth surface roughness may reach Ra0,4. Appropriate modiication and relatively high tooth surface roughness mayeffectively control the meshing noise and prolong the service life.