{"id":6470,"date":"2026-08-06T10:59:59","date_gmt":"2026-08-06T02:59:59","guid":{"rendered":"https:\/\/www.slewbearingtec.com\/?p=6470"},"modified":"2026-08-06T11:00:16","modified_gmt":"2026-08-06T03:00:16","slug":"slewing-gear-bearing-specs-gear-slew-torque-unlocked","status":"publish","type":"post","link":"https:\/\/www.slewbearingtec.com\/es\/slewing-gear-bearing-specs-gear-slew-torque-unlocked.html","title":{"rendered":"Slewing Gear Bearing Specs: Gear Slew Torque Unlocked"},"content":{"rendered":"
\n
\n

At many construction sites and on heavy\u2011duty machinery, what is commonly referred to as a \u201cslewing ring gear\u201d or a \u201cgeared slewing bearing\u201d is, in essence, a heavy\u2011duty rotary joint incorporating either an internal or external gear ring. It is specifically designed to transmit the substantial torque generated by the drive motor directly and efficiently to the equipment\u2019s rotating assembly.
If the old gear ring breaks and you need to replace it, there\u2019s a critical prerequisite: you must precisely match your hydraulic motor\u2019s output torque with the new bearing\u2011gear assembly\u2019s \u201cmaximum allowable tangential force.\u201d What happens if the selected parameters don\u2019t match? The consequences are clear: either, as soon as power is applied under heavy load, the gear teeth will shatter right in front of you; or the motor will be throttled to a standstill and burn out. Today, I\u2019ll lay out the underlying logic for nailing down torque parameters, hand you a selection matrix that guarantees no failures, and also expose those installation pitfalls on site that can instantly scrap a brand-new slewing bearing.<\/p>\n\n\n\n

\"Insert<\/figure>\n\n\n\n

<\/span>T.M.P. Torque matching matrix: choosing the right gear without asking for help<\/span><\/h2>\n\n\n\n

If you want to set the specifications for the replacement slewing bearing, you have to calculate the mechanical relationship between the main ring gear and the drive unit clearly. In order to help the maintenance masters on the scene to buy the right accessories without taking a mechanical engineering degree, I summarized a set of \u201cT.M.P. matrix\u201d (I .e. Teeth gear ring, Motor motor, Pinion pinion).<\/p>\n\n\n\n

<\/span>T-Teeth (ring gear): with internal teeth or external teeth?<\/span><\/h3>\n\n\n\n

The structure of your machine itself determines whether you need internal or external teeth. The tooth length of the external tooth slewing bearing is on the outer ring, and the diameter of the pitch circle is larger, so it can withstand a higher limit torque, and the maintenance inspection can be seen at a glance. The internal gear slewing bearing hides the teeth in the inner ring. Although it sacrifices a little limit torque limit, it can perfectly protect the meshing parts and completely isolate the damage of the harsh environment such as sediment and gravel on the construction site.<\/p>\n\n\n\n

<\/span>M-Motor (motor): calculate quasi-tangential force<\/span><\/h3>\n\n\n\n

Please memorize an iron law: the output torque of your drive motor must not exceed the maximum allowable tangential force (Tangential Force) of the slewing bearing. How? Just divide the maximum torque of the motor by the radius of the pinion. If the calculated force exceeds the rated limit calibrated by the manufacturer, once heavy load is encountered, the huge force of the motor will directly tear off the gear teeth on the big gear ring like a hand-torn chicken.<\/p>\n\n\n\n

<\/span>P-Pinion (pinion): the hardness must be suitable<\/span><\/h3>\n\n\n\n

The metal hardness of the small gear must match that of the large ring gear. If you take a steel pinion that has been deeply hardened and \u201chead-to-head\u201d with an ordinary large gear ring that has not been hardened, it is purely destructive. This \u201ccutting effect\u201d is terrible. In a few weeks, the tough pinion can grind the huge ring gear into a pile of metal powder.<\/p>\n\n\n\n

<\/span>The measured data speak: why does the ring gear break teeth?<\/span><\/h2>\n\n\n\n

The root cause of the broken tooth is one: the torque applied to it exceeds the strength limit of the core of the gear metal. In order to find out the gap, our team specially did a destructive torque test, taking the standard unhardened gear ring and the bearing treated with \u201ctooth surface local quenching (LTQ)\u201d to fight.<\/p>\n\n\n\n

Gear Treatment Process<\/th>Surface Hardness<\/th>Maximum Tangential Force Before Fracture<\/th>Field Results<\/th><\/tr><\/thead>
Unhardened Plain Carbon Steel<\/td>180 HB<\/td>45 kN<\/td>Under impact loading, the gear teeth bend directly and fail by shear fracture.<\/td><\/tr>
Localized Tooth Quenching (LTQ)<\/td>55 HRC<\/td>135 kN<\/td>The tooth surface remains hard and rigid, while the core retains high toughness, preventing brittle tooth fracture.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

It is clear from the data that the LTQ treatment can directly triple the torque resistance of the slewing bearing. Only the surface of the teeth is hardened, and the core body inside the gear is kept soft and tough. This \u201couter rigid and inner soft\u201d structure can be like a spring, strongly absorbing the severe impact force from the motor without breaking.<\/p>\n\n\n\n