Application of the outer gear ring

What is outer gear ring

The outer gear ring is a kind of ring gear with external teeth in the mechanical transmission system, which is usually used in conjunction with the internal ring gear, sun gear or planetary gear, etc., to transmit power and motion through inter-tooth meshing. Its structure is annular and the teeth are distributed on the outside of the circumference, which has high transmission efficiency and bearing capacity, and is the core component of planetary transmission, differential, reducer and other devices.

Characteristics of the outer gear ring

Large transmission ratio and compactness: Through the combination of planetary gear and sun gear, a large transmission ratio (such as planetary reducer) can be realized, and the structure is more compact than the traditional gearbox.

High load-bearing capacity: the tooth surface has a large contact area, can withstand high torque and impact loads, and is suitable for heavy-duty conditions (such as construction machinery, wind power equipment).

Two-way transmission adaptability: It can flexibly transmit forward and reverse power, which is commonly used in machinery that requires commutation (such as automobile transfer cases, robot joints).

Precision and low noise: High-precision machining (e.g., grinding and shaving) can reduce vibration and noise, and is suitable for precision transmission (e.g., medical equipment, aerospace gears).

Material diversity: alloy steel, stainless steel, cast iron or non-metallic materials can be selected according to working conditions, taking into account strength, corrosion resistance and economy.

Installation flexibility: It can be designed as a whole or a split type, which is easy to integrate with bearings, flanges and other components, and adapt to different space layouts.

Ease of maintenance: The modular design allows for the replacement of worn outer ring gears individually, reducing repair costs (e.g. mine conveyor drive chains).

Application of the outer gear ring

Industrial drive systems

Reducer and speed increaser

It is used in all kinds of reducers (such as planetary reducers, worm gears and worm reducers), and realizes large transmission ratios through the meshing of external gear rings and sun gears and planetary gears, which are commonly used in lifting equipment and metallurgical machinery.

Example: In a wind turbine gearbox, the outer gear ring is paired with a planetary wheel to convert low-speed and high-torque into high-speed output.

Transmission chains and conveyor belts

In mining conveyors and automated production lines, the external gear ring cooperates with the chain or rack to transmit power to realize material transportation or station movement.

Vehicles & Construction Machinery

Automobile transmission

Differential: The outer gear ring is combined with the half-shaft gear, allowing the left and right wheels to rotate at different speeds to adapt to cornering.

Transfer case: In off-road vehicles, the four-wheel drive mode is switched through the external gear ring to distribute power to the front and rear axles.

Construction machinery

The slewing mechanism of excavators and loaders uses the outer ring gear meshing with the inner ring gear to achieve 360° rotation of the platform, which needs to bear high torque and impact load.

Material selection: High-strength alloy steel (such as 20CrMnTi) is mostly selected and carburized and quenched to ensure wear resistance.

Precision Machinery & Instrumentation

Robot joints

The outer gear ring is used in harmonic reducer or RV reducer, and is used with flexible gears to achieve high-precision, low-backlash transmission, which is suitable for industrial robot arms.

Medical equipment

In the drive systems of dental drills and CT scans, the combination of outer gear rings and micro gears provides smooth, low-noise power transmission.

Energy & Environmental Equipment

wind generator

As a key component of the planetary gearbox, the outer gear ring converts the low-speed rotation of the impeller into the high-speed operation of the generator, which needs to bear long-term alternating loads.

Special design: Low-temperature toughness materials such as 34CrNiMo6 are used to cope with extreme environments.

Sewage treatment equipment

In the transmission system of the aerator and sludge scraper, the outer ring gear and the inner ring gear are coordinated to achieve underwater stirring, and stainless steel (such as 316L) needs to be used to prevent corrosion.

Special scenario applications

Aerospace

In the aircraft landing gear retraction mechanism and engine fuel pump, the external gear ring needs to meet the requirements of light weight and high reliability, and titanium alloy or high-strength aluminum alloy is used.

Marine Engineering

The transmission of the deep-sea exploration equipment uses an outer gear ring, which needs to be resistant to seawater corrosion and high-pressure sealing, and the material is often nickel-based alloys (e.g., Inconel 625).

How to choose the material of the outer gear ring?

The material selection of the outer gear ring should take into account the requirements of working conditions, performance requirements and economy, mainly based on the following principles:

1. Material type and characteristics

Carbon steel (such as 45# steel): low cost, good processability, suitable for light load, low speed and low precision requirements for scenarios (such as ordinary reducer).

Alloy structural steel (such as 20CrMnTi, 40Cr): strengthened by Cr, Ni, Mo and other alloying elements, the surface hardness can reach HRC58-62 after carburizing and quenching, and it is suitable for medium and high-speed and heavy-duty working conditions (such as automobile gearbox and construction machinery transmission).

Stainless steel (e.g. 316L, 1Cr18Ni9Ti): Excellent corrosion resistance, suitable for special applications such as humid, acid-alkali environments or food machinery, but with low strength and high cost.

Cast iron (such as ductile iron QT600): good shock absorption, low cost, but weak impact resistance, mostly used in low-speed, light-load fixed transmissions.

Non-metallic materials (such as polyoxymethylene, nylon): good self-lubrication, low noise, light weight, suitable for light load, low precision and insulating occasions (such as small instrument transmission).

2. Key Selection Factors

Load and speed: high-strength alloy carburizing steel (such as 17CrNiMo6) is required for heavy duty and high speed; Light loads are available in cast iron or non-metal.

Environmental conditions: stainless steel for wet/corrosive environments, high-temperature alloys (e.g. Inconel 718) for high-temperature environments, and high-wear-resistant materials for dusty environments.

Accuracy and life: Precision transmissions (such as aerospace gears) require high-purity alloy steel and high-precision heat treatment to reduce deformation.

Cost control: When mass production and performance requirements are not high, carbon steel or cast iron is preferred.

3. Heat treatment and surface treatment

Carburizing and quenching: improve the hardness and wear resistance of the tooth surface, suitable for alternating load conditions.

Nitriding treatment: Forming a high-hardness nitriding layer (HV900-1200), suitable for high-frequency impact or poor lubrication conditions.

Surface coatings: such as chrome plating, PVD coatings, enhance corrosion resistance and anti-friction properties.

4. Adaptation to special working conditions

Low-temperature environment: Choose materials with good low-temperature toughness (such as 30CrNi3A) to avoid cold brittleness.

High impact loads: Low-carbon martensitic steels (e.g. 20Cr2Ni4A) are used for both strength and toughness.

Summary: Material selection needs to be based on actual working conditions, balancing performance and cost. For example, the external gear ring of wind power gearbox is usually made of 20Cr2Ni4A carburized steel, which meets the requirements of high torque and fatigue resistance after carburizing and quenching; Food machinery may use 316L stainless steel outer gear ring, which is combined with nylon inner ring gear to achieve corrosion protection and silence.

Supplier of outer gear rings

LTZC BEARING's main products are slewing rings, non-standard precision bearings, rolling mill bearings, bearing-related unit assembly, and oversized precision guide rails. The product processing range is outer diameter: 200 mm - medium 10000 mm.

LTZC offers outer gear rings. If you are looking for a supplier of external gear rings, please contact us for the latest quotation.