Bevel Gears European Standard – DIN Type A & B, 1:1 to 1:4

Power transmission in a bevel gear pair works on the principle of conjugate tooth action between two conical pitch surfaces. When the two gears rotate, their teeth mesh along a contact line that sweeps across the tooth face from the small end (toe) toward the large end (heel). The line of contact is not parallel to either shaft axis, which is why the geometry must be treated as a cone-section problem rather than a simple cylindrical one.

The pitch cone angle of each gear in a pair determines how much of the full 90° intersection angle each gear contributes. For a 1:1 ratio (miter gear), both gears have a pitch cone angle of 45°. For a 1:2 ratio, the pinion has a pitch cone angle of approximately 26.6° and the ring gear approximately 63.4°. These angles are fixed by the ratio and cannot be adjusted independently, which is why specifying the gear ratio precisely is the first step in any bevel gear selection.

The tooth profile of a straight bevel gear traces an involute on the back cone, which is a plane perpendicular to the pitch cone surface at the large end of the tooth. For European standard bevel gears, the reference profile is a standard 20° pressure angle involute on the back cone. The tooth depth decreases from heel to toe in proportion to the cone distance, which means the tooth is thicker at the large end and tapers toward the small end — a geometrically necessary consequence of the conical pitch surface.

Type A

Type A bevel gears are the standard configuration for most enclosed gearbox applications. The gear body includes a hub that protrudes to one side of the pitch cone back face. The bore runs through the hub centrally. Mounting face and hub length dimensions are defined by the DIN series and are interchangeable with other manufacturers' Type A gears of the same module and ratio, which is significant for users sourcing replacements for European-designed gearboxes.

Common in: industrial gearboxes, conveyor drives, agricultural machinery, general-purpose right-angle drives

Type B

Type B bevel gears have a different hub geometry and back-cone face arrangement suited to applications where space behind the gear is constrained, or where the gear must be mounted flush against a housing wall without a projecting hub. The bore and keyway arrangement follows the DIN series for the relevant module. Type B should be specified when the original gearbox drawing or the housing configuration calls for it explicitly — substituting Type A where Type B is specified will result in an incorrect fit.

Common in: compact drives, power tools, instrumentation gearboxes, space-constrained mechanical assemblies

Bevel gears offer a distinct set of mechanical characteristics that make them the preferred solution for angular power transmission in a wide range of industries. The following summarises why designers specify bevel gears over alternative solutions such as worm gears, crossed-axis helicals, or universal joint arrangements:

1. Angular power transmission — the only gear type that efficiently changes drive direction between intersecting shafts. Alternative solutions (worm, belt-and-pulley, bevel-planetary combos) all carry trade-offs in efficiency, size, or cost that bevel gears avoid in the 90° right-angle case.
2. Compact design — bevel gears deliver the direction change and torque multiplication within the cone geometry, requiring less housing volume than a worm gear pair of equivalent power rating.
3. High efficiency — straight and spiral bevel gears operate at 97 to 99 percent mechanical efficiency per stage under full load. Worm gears at equivalent reduction ratios rarely exceed 90 percent, and the lost energy appears as heat that must be managed by the housing and lubricant system.
4. High load capacity — the tooth-face-width of a bevel gear is sized to carry the full design torque, and the conical geometry distributes stress across the face in a predictable way that is well-captured by AGMA and DIN stress calculations. Bevel gears handle shock loads and reverse loading better than worm stages of equivalent power rating.
5. Smooth operation — spiral bevel gears especially provide smooth, low-vibration operation through progressive tooth engagement. Even straight bevel gears at moderate pitch-line speeds operate with less noise than equivalent worm stages.
6. Easy maintenance — lubrication and periodic tooth-wear inspection are the primary maintenance tasks. Neither requires disassembly of the complete gearbox in most designs, and the tooth wear pattern is visible on inspection without special instruments.

Gear ratio, module, pitch cone angle, tooth depth, back-cone distance, and face width are calculated from the application requirements. For standard DIN ratios, these values follow the published DIN series tables; for custom ratios, our engineering team performs the full geometric calculation and issues a dimension sheet for customer approval before cutting begins.

The appropriate steel grade or other material is selected and the gear blank is prepared by forging or bar-stock machining to pre-gear dimensions. Material certificates are checked at incoming inspection. For case-hardening grades, the blank is normalised to relieve internal stress before gear cutting. Cast iron blanks for low-speed applications are prepared by rough machining to remove casting skin before the tooth-cutting stage.

Straight bevel teeth are generated using the Gleason or Coniflex methods on bevel gear generating machines. The Gleason method uses a rotating cutter and a generating process that creates the tooth profile by rolling the blank against the cutting tool — the tooth form emerges from the relative motion rather than being simply copied from a template. The Coniflex method uses a curved cutter that can generate both the tooth profile and the tooth depth in a single setup, which reduces setup time for small batches.

After gear cutting, parts undergo the specified heat treatment. Carburising and quenching produces a hard case over a tough core, which is the standard for gears in industrial and automotive gearboxes. Through-hardening provides uniform hardness for shock-loaded applications. Time-temperature curves for each batch are retained and available on request. Case depth is verified by cross-section metallographic inspection on sample pieces from each batch.

Depending on the required accuracy class, tooth finishing is performed by lapping (running the pair together with abrasive compound to optimise contact pattern and reduce surface roughness), gear grinding (for high-accuracy grades requiring tight transmission error and surface finish targets), or honing. Bore and mounting face final machining is performed after heat treatment to correct any distortion introduced during hardening.

Finished gears are inspected for tooth spacing error, pitch cone angle, runout, bore diameter, and surface hardness. Gear roll testing under load with contact pattern photography is performed on matched pairs. All dimensional and hardness data is recorded per order number and included with the shipment. Surface treatment — phosphating, black oxide, or zinc plating — is applied after final inspection where specified.

Selecting the correct bevel gear for a European standard application involves working through the following criteria in order. Skip any step that is already defined by the existing housing or system design:

1. Gear ratio — determine the required speed ratio between the two shafts. For DIN standard series this will be 1:1, 1:2, 1:3, or 1:4; other ratios require a custom gear pair.
2. Type A or Type B — identify the housing type from the original equipment drawing or by measuring the existing gear's hub geometry and back-cone face arrangement.
3. Module — calculated from the torque and speed requirements using standard DIN bending and contact stress formulas, or taken from the original equipment data sheet. Do not estimate module from a worn gear by measurement alone — worn teeth give systematically low module readings.
4. Tooth form — straight bevel for low-speed or reversing drives; spiral bevel for continuous high-speed operation or where noise is constrained.
5. Material and heat treatment — case-hardening alloy steel for maximum load capacity; through-hardening for shock loads; grey cast iron for large, slow drives where cost dominates; stainless steel for corrosive or food-contact environments.
6. Accuracy class — DIN quality class 8 or 9 for general-purpose drives; class 6 or 7 for higher speed or low-noise requirements; class 5 for precision instrument drives.
7. Surface treatment — phosphating or black oxide for corrosion protection in enclosed housings; zinc plating for outdoor or damp environments; as-machined for stainless steel or applications where dimensional change from plating is a concern.

What does "European standard" mean for bevel gears and why does it matter?

European standard bevel gears follow the DIN (Deutsches Institut für Normung) dimensional and accuracy system, which uses the metric module to define tooth size and the DIN 3971 / DIN 3975 standards to define tooth geometry and accuracy grades. This matters because European-designed gearboxes and machinery are dimensioned and specified in DIN terms — module, DIN quality class, and Type A or Type B hub configuration. A replacement gear sourced in AGMA diametral pitch will have different tooth dimensions for the same physical gear size, and cannot mesh correctly with the original mating gear. If you are replacing a gear in a European-origin machine, specifying European standard (DIN) is the only way to ensure geometric compatibility.

How do I identify the module of an existing DIN bevel gear?

The most reliable method is to find the original drawing or gearbox data plate, which will state the module directly. If neither is available, the module can be calculated from the outer diameter and tooth count: for a straight bevel gear, the outer (large-end) pitch diameter equals the module multiplied by the tooth count, so module = pitch diameter / tooth count. The tooth count is easy to count; the pitch diameter requires more care because it is not the same as the outer diameter — the tooth addendum must be subtracted. For a worn gear, this calculation tends to underestimate the module slightly because the addendum has been reduced by wear. When in doubt, send us a sample gear or a detailed sketch with outer diameter, hub diameter, hub length, tooth count, and face width measured, and we will identify the module and confirm the DIN series.

Can I use a straight bevel gear where a spiral bevel gear is currently installed?

Only if the original machine design allows it. Straight and spiral bevel gears of the same module, ratio, and outer diameter are not directly interchangeable — the tooth profile, contact pattern, and face-width geometry differ between them. More importantly, if the housing was designed for a spiral bevel gear at elevated speed, the noise and vibration levels from a straight bevel replacement will exceed the original design intent and may indicate the machine is running outside its design parameters. The reverse substitution — fitting a spiral bevel where a straight bevel was used — is mechanically possible if the housing geometry and shaft arrangement match, but the thrust loads on the bearings will change in magnitude and direction. Always consult the original gearbox specification before substituting tooth form.

What lubricant is recommended for enclosed DIN bevel gearboxes?

For most enclosed European standard bevel gearboxes running at moderate speed and ambient temperatures between 10°C and 40°C, ISO VG 220 gear oil with a GL-4 EP additive is the standard starting point. Gearboxes running hotter than 80°C, or at pitch-line speeds where churning loss is a concern with a heavier grade, benefit from a synthetic PAO gear oil of equivalent or lighter viscosity that maintains viscosity index over the operating temperature range. The gearbox original equipment documentation will usually specify the lubricant grade; for DIN-standard gearboxes this is often expressed as CLP 220 or CLP 320 per DIN 51517 Part 3, which maps to the ISO VG grade and EP additive requirement.

Do you stock standard DIN bevel gears or produce to order?

Korea Ever-Power produces to order rather than holding finished stock. This approach allows us to confirm the exact module, bore size, keyway, and tooth form for each customer's specific housing before production, which eliminates the fit and dimensional problems that arise from adapting a stocked gear to a housing it was not dimensioned for. Lead times for standard DIN series gears in common modules are typically shorter than for completely custom designs. Contact our team with your module, ratio, Type A or B, bore, and material requirement for a lead time estimate.

What documentation comes with each order of European standard bevel gears?

Every order ships with a material certificate confirming the steel grade and chemical composition, a heat treatment record, a dimensional inspection report covering pitch cone angle, tooth spacing error, runout, and bore, and a surface hardness test report at tooth flank and root. For matched pairs, a gear roll test contact pattern photograph is included. Additional non-destructive testing documentation — magnetic particle inspection or dye-penetrant — can be added at the quotation stage for safety-critical applications.

Can Korea Ever-Power supply both gears in a matched pair, or just one?

We supply both single gears and matched pairs depending on the application. For straight bevel gears at low to moderate speed, individual gears can be supplied since the contact pattern is largely determined by the mounting distance rather than by lapping. For spiral bevel gears, the ring gear and pinion should always be replaced as a matched pair because the contact pattern is optimised during the lapping stage for that specific pairing — mixing a new pinion with an old ring gear, or vice versa, will produce an inferior contact pattern and shorter service life. When in doubt, replace the pair. Send us your enquiry with the worn gear's measurements and we will advise on the best approach for your situation.

"We maintain a fleet of European-origin conveyors fitted with DIN bevel gearboxes. Sourcing replacement gears locally used to mean long waits for European imports. Ever-Power identified the correct module and Type A configuration from our sample gear, matched the DIN dimensions, and delivered with full material documentation. The gears fit and run correctly — no adjustment needed."

Oh Sang-woo  |  Maintenance Manager, Gyeongnam Logistics Centre  ·  Q3 2025

"We design packaging machines for the food industry and specify DIN bevel gear pairs throughout. Ever-Power supplies 316L stainless sets to our drawings at a reliable lead time. The dimensional reports they send match our incoming inspection measurements every time. Three years into the supply relationship, not one gear has been returned for quality reasons."

Jung Eun-ji  |  Lead Mechanical Engineer, Seoul Food Machinery Co.  ·  Q1 2026

"We needed a Type B bevel gear set in a non-standard 1:3 ratio for a conveyor head drive rebuild. The original European supplier's lead time was 14 weeks. Ever-Power produced the set to our DIN drawing, with heat treatment and hardness certification, in under five weeks. The gearbox has been back in production without issue."

Bae Jun-seo  |  Plant Reliability Engineer, Ulsan Chemical Plant  ·  Q2 2025

"We import German-designed mixing equipment and sometimes need to source replacement gears when the original manufacturer's delivery is too long. Ever-Power cross-referenced our module and DIN configuration accurately on the first quotation. The replacement gears were installed into the original housings without modification and passed our standard operational test."

Yoo Tae-yang  |  Equipment Manager, Incheon Chemical Processing  ·  Q4 2025

"We specified 20MnCr5 case-hardened straight bevel gears to DIN in a 1:2 ratio for a power tool gear train. Ever-Power supplied with carburising and quenching to the specified case depth, and the hardness test report showed consistent results across all pieces in the batch. Service life in our test rigs has met the design target."

Choi Dong-hyun  |  Design Engineer, Busan Power Tools R&D  ·  Q1 2026