{"id":1092,"date":"2026-06-24T03:34:44","date_gmt":"2026-06-24T03:34:44","guid":{"rendered":"https:\/\/planetary-gearboxes.com\/?p=1092"},"modified":"2026-06-24T03:36:35","modified_gmt":"2026-06-24T03:36:35","slug":"slewing-drive-planetary-gearbox-for-offshore-drilling-platforms","status":"publish","type":"post","link":"https:\/\/planetary-gearboxes.com\/th\/slewing-drive-planetary-gearbox-for-offshore-drilling-platforms\/","title":{"rendered":"\u0e40\u0e01\u0e35\u0e22\u0e23\u0e4c\u0e17\u0e14\u0e23\u0e2d\u0e1a\u0e41\u0e1a\u0e1a\u0e14\u0e32\u0e27\u0e40\u0e04\u0e23\u0e32\u0e30\u0e2b\u0e4c\u0e2a\u0e33\u0e2b\u0e23\u0e31\u0e1a\u0e41\u0e17\u0e48\u0e19\u0e02\u0e38\u0e14\u0e40\u0e08\u0e32\u0e30\u0e19\u0e2d\u0e01\u0e0a\u0e32\u0e22\u0e1d\u0e31\u0e48\u0e07"},"content":{"rendered":"
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Korea Ever-Power \u00b7 Application Engineering \u00b7 Offshore Drilling<\/p>\n

Slewing Drive Planetary Gearbox for Offshore Drilling Platforms \u2014 Rotating on a Foundation That Never Stops Moving<\/h1>\n

Salt water. Explosive atmospheres. Wave-induced motion. 24-hour drilling cycles. And the nearest spare-parts warehouse is a helicopter flight away. The \u0e0a\u0e38\u0e14\u0e40\u0e01\u0e35\u0e22\u0e23\u0e4c\u0e14\u0e32\u0e27\u0e40\u0e04\u0e23\u0e32\u0e30\u0e2b\u0e4c\u0e02\u0e31\u0e1a\u0e40\u0e04\u0e25\u0e37\u0e48\u0e2d\u0e19\u0e01\u0e32\u0e23\u0e2b\u0e21\u0e38\u0e19<\/strong> on an offshore drilling platform must survive conditions that would destroy any land-based drive within months \u2014 and it must do so for 20 to 30 years with maintenance windows measured in hours, not days.<\/p>\n

\u0e40\u0e23\u0e35\u0e22\u0e01\u0e14\u0e39\u0e0a\u0e38\u0e14\u0e40\u0e01\u0e35\u0e22\u0e23\u0e4c\u0e14\u0e32\u0e27\u0e40\u0e04\u0e23\u0e32\u0e30\u0e2b\u0e4c\u0e41\u0e1a\u0e1a\u0e2b\u0e21\u0e38\u0e19 \u2192<\/a><\/p>\n<\/div>\n<\/section>\n

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Where Slewing Drives Work on an Offshore Drilling Platform<\/h2>\n

An offshore drilling platform \u2014 jack-up, semi-submersible, or drillship \u2014 uses \u0e40\u0e01\u0e35\u0e22\u0e23\u0e4c\u0e17\u0e14\u0e23\u0e2d\u0e1a\u0e41\u0e1a\u0e1a\u0e40\u0e1f\u0e37\u0e2d\u0e07\u0e14\u0e32\u0e27\u0e40\u0e04\u0e23\u0e32\u0e30\u0e2b\u0e4c\u0e2a\u0e33\u0e2b\u0e23\u0e31\u0e1a\u0e02\u0e31\u0e1a\u0e40\u0e04\u0e25\u0e37\u0e48\u0e2d\u0e19\u0e01\u0e32\u0e23\u0e2b\u0e21\u0e38\u0e19<\/a> in multiple locations across the drilling and material-handling systems. Each location imposes a different combination of torque, speed, environment, and safety classification \u2014 but all share the common challenges of marine corrosion, wave motion, and restricted maintenance access.<\/p>\n

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Pedestal Cranes (2 \u2013 4 per platform)<\/div>\n

Offshore pedestal cranes rotate on the platform deck to handle drill pipe, casing, equipment, and supply vessel cargo. The slewing drive must operate in continuous salt spray while handling loads of 20 to 150 tonnes at radii of 20 to 50 metres. Slewing torque: 30,000 to 120,000 Nm. The crane is the lifeline of the platform \u2014 if it cannot slew, the platform cannot receive supplies or handle pipe.<\/p>\n<\/div>\n

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Iron Roughneck and Pipe Handling<\/div>\n

The iron roughneck (automated pipe wrench) and the pipe racking system use slewing drives to position drill pipe between the rack, the catwalk, and the well centre. These drives operate in the Zone 1 hazardous area \u2014 directly above the wellbore where hydrocarbon gas can be present. Slewing torque: 5,000 to 25,000 Nm. ATEX or IECEx certification is mandatory.<\/p>\n<\/div>\n

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Top Drive and Rotary Table Support<\/div>\n

Some drilling systems use slewing drives for the rotary table indexing or the top drive service loop management \u2014 positioning the drill string torque equipment around the well centre. These drives operate under the highest vibration loads on the platform, transmitted from the drill string through the derrick structure. Slewing torque: 10,000 to 40,000 Nm.<\/p>\n<\/div>\n

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BOP (Blowout Preventer) Handling<\/div>\n

The BOP transporter and test stump systems use slewing drives to rotate the 100 to 400 tonne blowout preventer stack during maintenance and testing. These are the heaviest loads any slewing drive on the platform handles \u2014 but they operate infrequently (every 2 to 4 weeks). Slewing torque: 80,000 to 200,000 Nm.<\/p>\n<\/div>\n<\/div>\n<\/div>\n

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\"Slewing<\/p>\n

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Slewing drive for offshore applications. Every unit must withstand continuous salt spray, wave-induced dynamic loading, and explosive atmosphere requirements \u2014 simultaneously, for 20 to 30 years.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/section>\n

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Wave Motion \u2014 The Dynamic Foundation That Adds Gyroscopic and Inertial Loads to Every Slewing Operation<\/h2>\n
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On land, a slewing drive rotates a load against gravity and friction. On an offshore platform, the slewing drive rotates a load against gravity, friction, AND the inertial forces generated by the platform motion. When the platform heaves (vertical motion) 3 metres in a 10-second wave period, every mass on the platform experiences an acceleration of approximately 0.3 g \u2014 increasing the effective weight of a 50-tonne crane load by 15 tonnes during the upward heave and reducing it by 15 tonnes during the downward heave.<\/p>\n

When the platform pitches (angular motion) 5 degrees at the same period, the crane boom \u2014 which is 30 metres from the slewing centre \u2014 experiences a lateral acceleration that generates a dynamic overturning moment in addition to the static moment. This wave-induced dynamic moment oscillates with the wave period, continuously adding and subtracting from the steady-state slewing torque requirement.<\/p>\n

\n\n\n\n\n\n\n\n
Sea State<\/th>\nHeave (m)<\/th>\nPitch (deg)<\/th>\nDynamic Load Factor<\/th>\nSlewing Torque Increase<\/th>\n<\/tr>\n<\/thead>\n
Calm (Hs < 1 m)<\/td>\n0.5 \u2013 1.0<\/td>\n1 \u2013 2<\/td>\n1.05 \u2013 1.10<\/td>\n+5 to +10%<\/td>\n<\/tr>\n
Moderate (Hs 2 \u2013 4 m)<\/td>\n2 \u2013 4<\/td>\n3 \u2013 6<\/td>\n1.15 \u2013 1.30<\/td>\n+15 to +30%<\/td>\n<\/tr>\n
Rough (Hs 4 \u2013 8 m)<\/td>\n4 \u2013 8<\/td>\n6 \u2013 10<\/td>\n1.30 \u2013 1.60<\/td>\n+30 to +60%<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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Why land-based sizing formulas undersize offshore drives:<\/strong> The wave-induced dynamic load factor adds 15 to 60% to the slewing torque requirement compared to the same load and radius on land. A slewing drive that is adequately rated for an 80-tonne lift at 30-metre radius on land (approximately 23,500 Nm) is undersized for the same lift at the same radius on a platform in moderate seas \u2014 the dynamic factor increases the requirement to 27,000 to 30,500 Nm. Offshore slewing drives must be rated using the DNV or API dynamic load factors for the site-specific sea state, not the static land-based calculation.<\/p>\n<\/div>\n<\/div>\n

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\"Slewing<\/p>\n

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The slewing drive on an offshore platform must handle both the steady-state load AND the wave-induced dynamic load \u2014 increasing the total torque requirement by 15 to 60% compared to the identical operation on land.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/section>\n

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\"Slewing<\/p>\n

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Offshore platform operations. Pedestal cranes, iron roughnecks, and pipe racking systems all rely on marine-grade slewing drives that must resist 20 to 30 years of continuous salt-spray corrosion while maintaining safe, precise rotation.<\/p>\n<\/div>\n<\/div>\n

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\"Precision<\/p>\n

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Precision gear manufacturing with marine-grade surface treatment. Offshore slewing drive gears receive additional corrosion-resistant coatings and surface hardening to withstand the salt-spray and humidity environment.<\/p>\n<\/div>\n<\/div>\n<\/div>\n

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ATEX and Explosive Atmosphere \u2014 The Requirement That Changes Everything About Material and Design Choices<\/h2>\n

On an offshore drilling platform, the drill floor and surrounding areas are classified as Zone 1 or Zone 2 hazardous atmospheres under ATEX (European Directive 2014\/34\/EU) or IECEx (international equivalent). In these zones, explosive gas-air mixtures can be present during normal operations (Zone 1) or during abnormal conditions (Zone 2). Any equipment operating in these zones \u2014 including slewing drives \u2014 must be designed to prevent ignition of the explosive atmosphere.<\/p>\n

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Surface Temperature Limit<\/div>\n

The external surface temperature of the slewing drive housing must not exceed the auto-ignition temperature of the gases present \u2014 typically 200 to 300 degrees C for hydrocarbon gases (T3 or T4 temperature class). This limit must be maintained under the worst-case operating condition: maximum torque, maximum ambient temperature, maximum solar radiation. The thermal design of the housing, the gear efficiency, and the lubricant type all affect the maximum surface temperature.<\/p>\n<\/div>\n

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No Sparking Materials<\/div>\n

If any part of the slewing drive is exposed to the hazardous atmosphere (such as the pinion-ring gear mesh), the materials must not produce sparks from friction, impact, or mechanical failure. Standard carbon steel on carbon steel can produce sparks. ATEX-rated gear meshes may require non-sparking pinion materials (copper-nickel alloys, certain bronzes) or full enclosure of the gear mesh in a flameproof housing. The enclosure approach (Exd \u2014 flameproof) is the most common solution for slewing drives on drill floors.<\/p>\n<\/div>\n

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Flameproof Enclosure (Exd)<\/div>\n

An Exd-rated slewing drive encloses the entire gear mechanism and motor in a housing designed to contain any internal explosion without transmitting flame to the external atmosphere. The housing wall thickness, flange gap dimensions, and fastener torque must all comply with IEC 60079-1 \u2014 adding 20 to 40% to the housing weight and cost compared to a standard non-ATEX drive. The housing must be pressure-tested to 1.5 times the maximum explosion pressure before delivery.<\/p>\n<\/div>\n<\/div>\n<\/section>\n

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Three Failure Modes Specific to Offshore Drilling Slewing Drives<\/h2>\n
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1<\/div>\n
Marine corrosion of the slewing bearing raceway from continuous salt-spray exposure<\/div>\n<\/div>\n

The slewing bearing raceway \u2014 the hardened steel surface on which the bearing balls or rollers run \u2014 is the most corrosion-sensitive component in the offshore slewing drive. Salt spray penetrates through the bearing seal and mixes with the grease. Chloride ions in the salt water initiate pitting corrosion on the raceway surface. Each pit becomes a stress concentration that propagates into fatigue spalling under the rolling contact load. Unlike land-based slewing drives (where corrosion is negligible over 10 to 20 years), offshore bearing raceways can develop visible pitting within 3 to 5 years without adequate corrosion-inhibiting grease and seal maintenance.<\/p>\n

Prevention: Use corrosion-inhibiting bearing grease (sodium complex or lithium complex with rust inhibitor). Automatic bearing re-lubrication at 500 to 1,000 hour intervals. Inspect bearing play at every annual survey. Freshwater rinse of the exposed bearing seal area during washdown cycles.<\/div>\n<\/div>\n
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2<\/div>\n
Gear tooth fatigue from continuous wave-induced dynamic loading<\/div>\n<\/div>\n

Every wave cycle adds a dynamic torque component to the slewing drive load \u2014 5 to 10 seconds per cycle, 6 to 12 cycles per minute, 24 hours per day. Over one year of continuous operation, the gear teeth experience 3 to 6 million additional stress cycles from wave motion alone \u2014 far exceeding the number of cycles from the actual slewing operations. The wave-induced fatigue is low-amplitude but high-cycle \u2014 the most damaging combination for case-hardened gear tooth surfaces. Standard land-based gear fatigue calculations understate the tooth life by 30 to 50% if wave-induced cycling is not included.<\/p>\n

Prevention: Size gears using the DNV-ST-0376 or API 2C dynamic load spectrum, not static land-based calculations. Specify DIN Class 5 gears with superfinished flanks. Use Korea Ever-Power planetary gearboxes<\/a> with 18CrNiMo7-6 gear steel rated for the offshore high-cycle fatigue spectrum.<\/div>\n<\/div>\n
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3<\/div>\n
Flameproof housing seal degradation allowing loss of Exd integrity<\/div>\n<\/div>\n

The flameproof (Exd) housing relies on precision-machined flange gaps to contain any internal ignition. These gaps must remain within the IEC 60079-1 dimensional tolerance for the entire service life. Salt corrosion, thermal cycling, and mechanical impact from routine platform operations can widen the flange gaps beyond the certified dimensions. Once the gap exceeds the maximum permitted value, the housing is no longer certified to contain an internal explosion \u2014 and the drive becomes a potential ignition source in the Zone 1 atmosphere. This degradation is invisible from outside the housing and can only be detected by dimensional inspection of the flange gap during a scheduled inspection.<\/p>\n

Prevention: Flange gap measurement at every 5-year major survey. Corrosion protection of flange surfaces with marine-grade primer. Torque-verify all housing bolts at annual inspections. Replace the housing if flange gap exceeds 75% of the IEC 60079-1 maximum.<\/div>\n<\/div>\n<\/div>\n<\/div>\n
\"Korea
\n\"Korea<\/p>\n
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Top: Korea Ever-Power manufacturing facility. Bottom: Testing centre \u2014 offshore drives undergo marine-grade corrosion testing, ATEX housing pressure verification, and dynamic torque simulation before delivery.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/section>\n

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Slewing Drive Planetary Gearbox for Offshore Drilling Platforms \u2014 Frequently Asked Questions<\/h2>\n
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How does wave motion affect slewing drive specification compared to land-based cranes?<\/h3>\n

Wave-induced platform motion adds dynamic load factors of 1.15 to 1.60 to the static slewing torque \u2014 meaning the offshore drive must be rated 15 to 60% higher than the identical load and radius on land. Additionally, the continuous wave cycling (3 to 6 million cycles per year) produces gear tooth fatigue that does not exist on land. Land-based crane slewing drive sizing formulas use static safety factors of 1.5 to 2.0; offshore specifications use DNV or API dynamic factors that account for the site-specific sea state, wave period, and platform response characteristics. A drive that is correctly sized for an onshore crane at the same capacity will be undersized for offshore service by 15 to 40%.<\/p>\n<\/div>\n

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What is the typical service life of an offshore slewing drive?<\/h3>\n

15,000 to 25,000 operating hours for the planetary gearbox. The slewing bearing may require replacement at 10,000 to 15,000 hours due to corrosion-accelerated raceway pitting. The pinion typically lasts 8,000 to 15,000 hours depending on the exposure level and greasing discipline. For ATEX-rated drives, the flameproof housing must be dimensionally verified at every 5-year survey \u2014 if the flange gaps exceed the IEC 60079-1 maximum, the housing must be refurbished or replaced regardless of the gearbox condition.<\/p>\n<\/div>\n

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Is ATEX certification required for all slewing drives on an offshore platform?<\/h3>\n

No \u2014 only for drives operating in classified hazardous areas (Zone 1 or Zone 2). The drill floor, the wellbore area, and the shale shaker room are typically Zone 1. The main deck, accommodation areas, and utility rooms are typically non-hazardous. Pedestal cranes mounted on the main deck outside the hazardous zone do not require ATEX certification for the slewing drive \u2014 but do require marine-grade corrosion protection. Pipe handling equipment, iron roughnecks, and any drive positioned on or near the drill floor typically require ATEX or IECEx certification. The hazardous area classification plan for the specific platform determines which drives need ATEX certification.<\/p>\n<\/div>\n

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What coating system is required for offshore slewing drive housings?<\/h3>\n

C5-M (marine, very high corrosivity) per ISO 12944 \u2014 the highest corrosion class for atmospheric exposure. This typically requires a multi-coat system: inorganic zinc primer (75 micron) + epoxy intermediate coat (150 micron) + polyurethane topcoat (60 micron) = minimum 285 micron total dry film thickness. Alternatively, hot-dip galvanisation (85+ micron) with a sealed topcoat provides equivalent or superior protection. All exposed fasteners must be A4-80 stainless steel or hot-dip galvanised. For splash zone installations (within 3 metres of the waterline), additional abrasion-resistant coatings or rubber sheeting is required to resist wave-impact damage to the coating system.<\/p>\n<\/div>\n

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Does Korea Ever-Power supply offshore-rated and ATEX-certified slewing drives?<\/h3>\n

Yes. Korea Ever-Power manufactures slewing drive planetary gearboxes for offshore drilling platform applications with C5-M marine coating systems, DNV-rated dynamic load capacity, and ATEX\/IECEx flameproof housing options for Zone 1 and Zone 2 installations. Available from 5,000 to 200,000 Nm for pipe handling, pedestal cranes, top drive support, and BOP handling. 18CrNiMo7-6 gear steel with DIN Class 5 surface finish is standard for the offshore high-cycle fatigue environment. Provide the platform type (jack-up\/semi-sub\/drillship), equipment application, hazardous area classification, and site-specific sea state for a specification matched to the DNV or API dynamic load requirements.<\/p>\n<\/div>\n<\/div>\n<\/section>\n

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Offshore Drilling Slewing Drives \u2014 Marine-Grade, Wave-Rated, ATEX-Certified<\/div>\n

Korea Ever-Power provides offshore drilling platform slewing drive planetary gearboxes with DNV dynamic load ratings, C5-M marine coatings, and ATEX flameproof options from 5,000 to 200,000 Nm. Provide your platform type and equipment application for a marine-rated specification.<\/p>\n<\/div>\n

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\u0e14\u0e39\u0e2a\u0e34\u0e19\u0e04\u0e49\u0e32\u0e43\u0e19\u0e01\u0e25\u0e38\u0e48\u0e21\u0e0a\u0e38\u0e14\u0e02\u0e31\u0e1a\u0e2b\u0e21\u0e38\u0e19 \u2192<\/a><\/p>\n

sales@planetary-gearboxes.com<\/div>\n<\/div>\n<\/div>\n<\/section>\n

\u0e1a\u0e23\u0e23\u0e13\u0e32\u0e18\u0e34\u0e01\u0e32\u0e23: Cxm<\/p>\n<\/div>","protected":false},"excerpt":{"rendered":"

Korea Ever-Power \u00b7 Application Engineering \u00b7 Offshore Drilling Slewing Drive Planetary Gearbox for Offshore Drilling Platforms \u2014 Rotating on a Foundation That Never Stops Moving Salt water. Explosive atmospheres. Wave-induced motion. 24-hour drilling cycles. And the nearest spare-parts warehouse is a helicopter flight away. The slewing drive planetary gearbox on an offshore drilling platform must […]<\/p>","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_et_pb_use_builder":"","_et_pb_old_content":"","_et_gb_content_width":"","footnotes":""},"categories":[965],"tags":[],"class_list":["post-1092","post","type-post","status-publish","format-standard","hentry","category-application-and-technical-guid"],"_links":{"self":[{"href":"https:\/\/planetary-gearboxes.com\/th\/wp-json\/wp\/v2\/posts\/1092","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/planetary-gearboxes.com\/th\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/planetary-gearboxes.com\/th\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/planetary-gearboxes.com\/th\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/planetary-gearboxes.com\/th\/wp-json\/wp\/v2\/comments?post=1092"}],"version-history":[{"count":3,"href":"https:\/\/planetary-gearboxes.com\/th\/wp-json\/wp\/v2\/posts\/1092\/revisions"}],"predecessor-version":[{"id":1096,"href":"https:\/\/planetary-gearboxes.com\/th\/wp-json\/wp\/v2\/posts\/1092\/revisions\/1096"}],"wp:attachment":[{"href":"https:\/\/planetary-gearboxes.com\/th\/wp-json\/wp\/v2\/media?parent=1092"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/planetary-gearboxes.com\/th\/wp-json\/wp\/v2\/categories?post=1092"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/planetary-gearboxes.com\/th\/wp-json\/wp\/v2\/tags?post=1092"}],"curies":[{"name":"\u0e14\u0e31\u0e1a\u0e40\u0e1a\u0e34\u0e25\u0e22\u0e39\u0e1e\u0e35","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}