Descrizione
Internal Gear Ring
42CrMo Alloy Steel · Gas Nitrided · HV550–600 · Case Depth 0.3–0.5 mm
Precision-manufactured ring gears for UK wind energy, mining, construction, offshore, and food processing industries. Custom sizes, tight tolerances, full material traceability.
The internal gear ring — also called a ring gear or annular gear — forms the outer fixed element of a planetary gearbox, transmitting torque through its internal tooth profile to a set of planet gears. Because the mesh occurs on the inside of the ring rather than the outside, planetary arrangements achieve a far higher torque-to-weight ratio in a given housing diameter than any equivalent parallel-shaft design, which is precisely why they dominate demanding sectors such as wind turbine drivetrains, excavator final drives, and industrial speed reducers across the United Kingdom.
Ever Power produces every internal gear ring from 42CrMo chromium-molybdenum alloy steel and subjects each component to a carefully controlled gas nitriding cycle. The outcome is a surface hardness of HV550–600 with a case depth between 0.3 mm and 0.5 mm — a combination that delivers exceptional flank wear resistance while the tough, ductile core handles shock loading without fracture. UK engineers specifying replacement or new-build planetary drives consistently report measurable improvements in overhaul intervals after switching to our nitrided ring gears.
Technical Specifications
| Parameter | Specification |
|---|---|
| Product Name | Internal Gear Ring |
| Material | 42CrMo |
| Heat Treatment | Nitriding |
| Hardness | HV550~600 |
| Case Depth | 0.3~0.5 mm |
Why UK Engineers Specify Our Internal Gear Ring
A post-nitriding hardness of HV550–600 ensures tooth flanks resist micro-pitting and abrasive wear under sustained radial and tangential loads. This matters enormously in UK quarrying, aggregate processing, and mining — sectors where gearbox components face relentless impact stress around the clock. Operators in Yorkshire and South Wales have documented a dramatic reduction in visible flank wear during routine inspections compared with standard steel ring gears.
42CrMo alloy steel is celebrated across British engineering circles for combining high tensile strength with genuine impact toughness. Gas nitriding hardens only the outer 0.3–0.5 mm, leaving the core ductile enough to absorb shock loads that would crack a through-hardened component. This hard-surface/tough-core architecture is difficult to replicate with lower-grade steels, and it is a principal reason experienced UK plant engineers specify 42CrMo as their material of choice for heavily loaded ring gears.
Unlike carburising and oil quenching, gas nitriding is a pure diffusion process — there is no phase transformation, no rapid temperature drop, and therefore no appreciable thermal warping. Internal gear rings exit the nitriding furnace with tooth profiles that still conform to DIN or ISO tolerances without the need for full profile regrinding. UK procurement teams appreciate this directly: shorter lead times, lower piece prices, and faster delivery to site.
The iron nitride compound layer formed during nitriding significantly improves resistance to oxidation and surface corrosion — a practical benefit for internal gear rings operating on UK offshore platforms, water treatment works, and food processing facilities where wash-down procedures or salt-laden atmospheres would otherwise accelerate surface degradation. Our rings arrive cleaned, coated with a rust-preventative oil, and double-packaged for transit and storage.
The synergy between a hard nitrided surface and a tough 42CrMo core delivers a ring gear that simply outlasts standard alternatives. UK customers working in wind energy, offshore, and heavy industry have reported maintenance intervals extending by 40–60% after switching to our specification. Over a five-year horizon on a gearbox with five-figure overhaul costs, that extension represents a compelling return on the modest price premium over commodity ring gears.
No two applications are identical. Every internal gear ring we produce can be customised to your module, pitch diameter, tooth count, bore size, keyway specification, flange geometry, and surface finish requirement. Send us a drawing, a 3D model, or even a physical sample — our engineers will review your requirement and provide a manufacturability assessment before you commit to an order.
Material, Nitriding Process & Industry Applications
42CrMo is a chromium-molybdenum low-alloy engineering steel standardised under EN 10083-3 and used throughout European and British manufacturing. Its chromium content promotes hardenability and mild corrosion resistance, while molybdenum suppresses temper embrittlement and improves creep strength at elevated operating temperatures. In the quenched and tempered condition, tensile strength falls between 900 and 1,100 MPa, providing an ideal base for highly loaded internal gear rings that must carry significant torque without fatigue failure across years of continuous service.
Our gas nitriding process runs at 500–530 °C in a controlled atmosphere of dissociated ammonia for a precisely timed cycle determined by the required case depth. Nitrogen atoms diffuse into the steel lattice and react with chromium, molybdenum, and iron to form hard nitride precipitates throughout the case layer. Because there is no quench — no sudden temperature shock — components exhibit minimal geometric distortion. Finished internal gear rings typically require only a light honing or no post-treatment grinding at all, preserving dimensional accuracy and accelerating delivery schedules.
Across the United Kingdom, our internal gear rings are installed in applications ranging from 2 MW wind turbine planetary gearboxes operating in Scottish wind farms, to slewing ring drives on HS2 corridor civil engineering plant, to food-grade conveyor reducers in Yorkshire and Lincolnshire processing facilities. The table below maps key application types to their sector and primary gear ring requirement:
| Application | UK Sector / Region | Primary Requirement |
|---|---|---|
| Planetary Gearbox Ring Gear | Wind Energy, Scotland / North Sea | High fatigue life, low noise output |
| Slewing Drive Ring Gear | Construction, HS2 Corridor | High torque density, impact durability |
| Underground Loader Wheel Drive | Mining, Yorkshire / Wales | Shock resistance, compact envelope |
| Rotary Kiln Drive Ring | Cement & Lime, Pennines | Thermal stability, long overhaul life |
| Servo Actuator Ring Gear | Aerospace, Bristol / Derby | Tight tolerance, minimal distortion |
| Conveyor Reducer Ring Gear | Food Processing, Yorkshire / Lincolnshire | Corrosion resistance, wash-down safe |
Customer Success Stories
Wind Turbine Gearbox OEM Eliminates Premature Flank Wear Across 84-Unit UK Fleet
A well-established wind turbine gearbox original equipment manufacturer based in Aberdeen approached Ever Power in 2022 after repeated instances of premature tooth flank wear on internal gear rings sourced from their then-current domestic supplier. Their 2 MW onshore turbines were accumulating over 6,000 load hours annually, and affected ring gears were showing visible pitting after just 18 months in service — well short of the five-year inspection target stipulated in their maintenance contracts with UK energy operators.
Ever Power’s engineering team reviewed the client’s housing drawings and existing gear geometry, confirming that the ring gear geometry was sound but the surface treatment was inadequate for the load cycle. A batch of 42CrMo nitrided internal gear rings was manufactured to the original tooth profile dimensions with a tightened runout tolerance and a 0.4 mm nitriding case depth. The first batch was installed across 12 turbines and entered service at full rated load.
Following a 26-month in-service evaluation, borescope inspection of all 12 test gearboxes showed no measurable flank wear, no micro-pitting, and consistent tooth root condition at or beyond the OEM’s original five-year standard. The client subsequently placed a blanket purchase agreement for internal gear rings covering all 84 turbines in their UK fleet, projecting a 35% reduction in unplanned gearbox overhaul expenditure across the next contract period.
“We specified custom internal gear rings for the planetary final drives on our tunnel boring machines running on the HS2 project. Ever Power delivered to DIN Grade 5 tolerance within six weeks of receiving our drawings — even with the custom bore and keyway arrangement we needed. The nitrided surface is holding up perfectly under the vibration loading from rock cutting. Genuinely one of the strongest supplier relationships we have built.”
“Sourcing reliable ring gears for our offshore hydraulic slewing drives has always been challenging until we started working with Ever Power. The 42CrMo nitrided internal gear rings have now completed two full North Sea operating seasons without a single failure or detectable wear step. Lead time was realistic, pricing was competitive, and the material traceability documentation was exactly what our asset integrity team required.”
“Our food processing conveyors run 20 hours a day. We needed a gear ring supplier who could match exact bore tolerances and supply full material certificates and heat treatment records for our BRC audit programme. Ever Power delivered on every point — the documentation was complete, accurate, and ready before the parts landed. We now use them exclusively for all planetary gear components across our three Yorkshire sites.”
Manufacturing Capabilities & Custom Gear Ring Services
Ever Power’s vertically integrated manufacturing facility houses CNC internal gear grinding centres, CNC hobbing machines, gear shapers, and multi-axis turning lathes capable of producing internal gear rings from module 1 up to module 30 and pitch diameters spanning 50 mm to 3,000 mm. Our in-house metrology laboratory is equipped with Zeiss CMM and dedicated gear measuring instruments that verify every finished component against customer tolerances or DIN/ISO 1328 quality grades prior to despatch.
Our custom gear ring service is one of the most comprehensive offered by any single manufacturer supplying the UK market. We handle non-standard tooth profiles — involute, cycloidal, and helical cuts with bespoke pressure angles — as well as special bore diameters, keyways, splines, flanges, and through-holes for lubrication. Beyond nitriding, we offer additional surface treatments including phosphating, black oxidising, and electroless nickel plating. For applications where 42CrMo is not the optimum choice, we stock and machine 20CrMnTi, 18CrNiMo7-6, 40Cr, and selected stainless grades. Where drawings do not exist, our engineers carry out full reverse-engineering from physical samples or dimensional surveys.
We hold ISO 9001:2015 certification and can supply EN 10204 3.1 material certificates, full heat treatment furnace records, calibrated hardness test data, and CMM inspection reports as standard or on request — satisfying the documentation requirements of UK aerospace primes, energy operators, and food safety auditors alike. Whether your need is a single prototype to validate a new gearbox design or a standing quarterly order for series production, our team will structure lead times, packaging, and documentation to your exact requirements. Contact us today to discuss your specification and receive a formal quotation within 48 hours.
Frequently Asked Questions
edit by gzl
