{"id":1034,"date":"2026-06-23T05:45:54","date_gmt":"2026-06-23T05:45:54","guid":{"rendered":"https:\/\/planetary-gearboxes.com\/?p=1034"},"modified":"2026-06-23T05:45:54","modified_gmt":"2026-06-23T05:45:54","slug":"track-drive-planetary-gearbox-for-crawler-cranes","status":"publish","type":"post","link":"https:\/\/planetary-gearboxes.com\/fi\/track-drive-planetary-gearbox-for-crawler-cranes\/","title":{"rendered":"Track Drive Planetary Gearbox for Crawler Cranes"},"content":{"rendered":"
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\"Track<\/p>\n
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Application Engineering<\/span>
\nCrawler Cranes<\/span><\/div>\n

Track Drive Planetary Gearbox for Crawler Cranes \u2014 Moving 500 Tonnes at Walking Speed<\/h1>\n

A bulldozer pushes hard and fast. An excavator pivots and repositions. A crawler crane does neither. It carries \u2014 slowly, deliberately, with absolute control \u2014 the heaviest single load that any self-propelled tracked machine places on the ground. The track drive that enables this movement is engineered for a set of priorities that no other tracked machine shares.<\/p>\n

Browse Track Drive Planetary Gearboxes \u2192<\/a><\/p>\n<\/div>\n<\/div>\n<\/section>\n

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Why Crawler Crane Track Drives Are Engineered Differently from Every Other Final Drive<\/h2>\n

The track drive planetary gearbox<\/a> on a crawler crane faces a unique combination of constraints that no excavator, bulldozer, or loader encounters. Understanding these constraints explains why crane track drives are not simply oversized versions of excavator final drives \u2014 they are a fundamentally different engineering package.<\/p>\n

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Extreme Weight, Minimal Travel<\/div>\n

A 300-tonne crawler crane weighs 280 to 320 tonnes without a load. Add counterweight, boom, and a 100-tonne suspended load, and the track drives carry 400 to 500 tonnes across the ground. Yet the machine may travel only 50 to 200 metres per day \u2014 repositioning between lifts. The track drive duty cycle is 1 to 3%: the lowest of any tracked machine, but at the highest single-event load.<\/p>\n<\/div>\n

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Controlled Speed, Not Maximum Speed<\/div>\n

Crawler crane travel speed is typically 0.7 to 1.5 km\/h \u2014 walking pace. Higher speed would compromise stability, exceed ground bearing pressure limits during acceleration, and risk pendulum swing of suspended loads. The track drive is deliberately geared for extremely low output speed at high torque \u2014 ratios of 150:1 to 300:1 are common, far exceeding the 40:1 to 120:1 range used in excavators.<\/p>\n<\/div>\n

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Braking Is More Important Than Driving<\/div>\n

On a slope \u2014 even a 2 to 3% gradient that looks flat to the eye \u2014 a 500-tonne crane will accelerate under gravity if the track drives cannot hold. The parking brake inside the track drive planetary gearbox must hold the full machine weight on the steepest expected gradient indefinitely. This braking requirement often determines the track drive specification before the driving torque calculation is even considered.<\/p>\n<\/div>\n<\/div>\n<\/section>\n

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Ground Bearing Pressure \u2014 The Constraint That Governs Crawler Crane Track Drive Design<\/h2>\n

Before a crawler crane can travel, the ground must support it. Ground bearing pressure (GBP) \u2014 the force per unit area that the tracks exert on the ground surface \u2014 determines whether the crane sinks, tilts, or remains stable. The track drive gearbox contributes to GBP through its own weight and through the dynamic forces it generates during acceleration and braking.<\/p>\n

\n\n\n\n\n\n\n\n\n
Crane Class<\/th>\nTotal Weight (t)<\/th>\nTrack Length (m)<\/th>\nTrack Width (mm)<\/th>\nGBP (kPa)<\/th>\nTrack Drive Torque (Nm)<\/th>\n<\/tr>\n<\/thead>\n
50 \u2013 80 t lattice<\/td>\n60 \u2013 100<\/td>\n4.0 \u2013 5.5<\/td>\n600 \u2013 700<\/td>\n55 \u2013 80<\/td>\n40,000 \u2013 70,000<\/td>\n<\/tr>\n
100 \u2013 200 t lattice<\/td>\n130 \u2013 260<\/td>\n5.5 \u2013 7.5<\/td>\n700 \u2013 900<\/td>\n70 \u2013 110<\/td>\n80,000 \u2013 160,000<\/td>\n<\/tr>\n
300 \u2013 500 t lattice<\/td>\n350 \u2013 600<\/td>\n8.0 \u2013 12.0<\/td>\n900 \u2013 1,200<\/td>\n90 \u2013 140<\/td>\n180,000 \u2013 350,000<\/td>\n<\/tr>\n
600 \u2013 750 t lattice<\/td>\n700 \u2013 1,000<\/td>\n10.0 \u2013 14.0<\/td>\n1,000 \u2013 1,500<\/td>\n100 \u2013 160<\/td>\n400,000 \u2013 700,000<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

GBP is static (no dynamic amplification). Track drive torque is per-track for level travel at 1.0 km\/h. Typical ground allowable bearing pressure: compacted gravel 150 \u2013 200 kPa, timber mats on clay 80 \u2013 120 kPa, unimproved soil 50 \u2013 80 kPa. When GBP exceeds ground capacity, timber crane mats or steel plates are mandatory.<\/p>\n<\/section>\n

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Travel Torque Calculation \u2014 Sizing the Track Drive for a 200-Tonne Crawler Crane<\/h2>\n

The worked example below demonstrates the complete torque sizing process for a medium-class lattice boom crawler crane. Note the differences from the excavator and bulldozer calculations: the speeds are much lower, the ratios are much higher, and the braking torque calculation appears as a separate mandatory check.<\/p>\n

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Crawler Crane Travel Drive Sizing \u2014 200 t Lattice Boom<\/div>\n
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Annettu:<\/div>\n
\u00a0\u00a0Crane total weight (with CW + boom): 260,000 kg<\/div>\n
\u00a0\u00a0Number of track drives: 2 (one per crawler)<\/div>\n
\u00a0\u00a0Sprocket PCD: 900 mm (r = 0.45 m)<\/div>\n
\u00a0\u00a0Target travel speed: 1.0 km\/h = 0.278 m\/s<\/div>\n
\u00a0\u00a0Rolling resistance coefficient (gravel pad): 0.04<\/div>\n
\u00a0\u00a0Maximum gradient during travel: 3% (1.72 degrees)<\/div>\n
Step 1 \u2014 Rolling resistance per track:<\/div>\n
\u00a0\u00a0F_roll = (260,000 x 9.81 x 0.04) \/ 2<\/div>\n
\u00a0\u00a0F_roll = 51,012 N per track<\/strong><\/div>\n
Step 2 \u2014 Grade resistance per track (3% slope):<\/div>\n
\u00a0\u00a0F_grade = (260,000 x 9.81 x sin(1.72)) \/ 2<\/div>\n
\u00a0\u00a0F_grade = 38,276 N per track<\/strong><\/div>\n
Step 3 \u2014 Total driving torque per track:<\/div>\n
\u00a0\u00a0T = (F_roll + F_grade) x r = (51,012 + 38,276) x 0.45<\/div>\n
\u00a0\u00a0T = 40,180 Nm per track (steady-state)<\/strong><\/div>\n
Step 4 \u2014 Apply SF = 1.5 (crane travel \u2014 no counter-rotation, low shock):<\/div>\n
\u00a0\u00a0T_required = 40,180 x 1.5 = 60,270 Nm minimum rated torque<\/strong><\/div>\n
Step 5 \u2014 BRAKING CHECK (mandatory for cranes):<\/div>\n
\u00a0\u00a0Brake must hold crane on 5% slope (worst-case pad gradient):<\/div>\n
\u00a0\u00a0F_brake = (260,000 x 9.81 x sin(2.86)) \/ 2 = 63,716 N per track<\/strong><\/div>\n
\u00a0\u00a0T_brake = 63,716 x 0.45 = 28,672 Nm brake holding torque per track<\/strong><\/div>\n
\u2192 Specify: Driving torque \u2265 60,270 Nm + Brake \u2265 28,672 Nm<\/div>\n
\u2192 Korea Ever-Power 80,000 Nm track drive with 35,000 Nm spring-applied brake \u2714<\/div>\n<\/div>\n<\/div>\n
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Why the crane calculation includes a separate braking check<\/div>\n

Neither bulldozers nor excavators require a separate brake sizing calculation \u2014 their track drives use spring-applied hydraulic-release brakes sized to the motor stall torque, which always exceeds the grade-holding requirement for these lighter machines. Crawler cranes, at 260 to 1,000 tonnes, generate grade-holding forces that can approach or exceed the motor stall torque \u2014 especially on uneven ground where one track bears a disproportionate share of the load. The brake must be independently verified against the worst-case gradient and asymmetric loading condition, not simply assumed adequate because it matches the motor torque.<\/p>\n<\/div>\n<\/section>\n

\"Track<\/p>\n

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Travel with Suspended Load \u2014 The Safety Constraint That Drives Track Drive Speed Control<\/h2>\n

Some crawler crane operations require the crane to travel while carrying a suspended load \u2014 moving a structural steel member from the laydown area to the erection point, or repositioning during a tandem lift. This “pick and carry” operation imposes the most severe stability constraint on the track drive system.<\/p>\n

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Pendulum Effect<\/div>\n

A suspended load acts as a pendulum. Any acceleration, deceleration, or change in direction of the crane causes the load to swing. The swinging load shifts the centre of gravity dynamically \u2014 and on a 300-tonne crane carrying a 50-tonne load at a 30-metre radius, the dynamic CG shift can approach the tipping boundary. The track drive must accelerate and decelerate so gradually that the pendulum amplitude never exceeds the stability margin. This translates to acceleration limits of 0.01 to 0.03 m\/s2 \u2014 approximately 1\/300th of the acceleration a car applies when pulling away from a traffic light.<\/p>\n<\/div>\n

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Speed Limit During Carry<\/div>\n

Most crane manufacturers limit travel speed to 0.5 to 0.8 km\/h during pick-and-carry \u2014 half the already-slow normal travel speed. The track drive must provide smooth, stepless speed control from zero to maximum at this reduced speed. Any jerky motion, torque pulsation, or speed hunting in the track drive hydraulic circuit translates directly into load swing. The planetary gearbox backlash specification is tighter for crane track drives than for excavator track drives because backlash produces a momentary speed discontinuity during direction change that initiates pendulum oscillation.<\/p>\n<\/div>\n<\/div>\n

The slewing drive planetary gearbox<\/a> that rotates the crane superstructure faces a similar pendulum constraint during slewing with a suspended load \u2014 but the track drive faces the additional complication of ground surface irregularities (bumps, ruts, soft spots) that introduce vertical perturbations into the pendulum system. The track drive and the slewing drive must be engineered as a coordinated pair, not as independent systems.<\/p>\n<\/section>\n

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The Parking Brake \u2014 Why Crawler Crane Track Drives Require Spring-Applied Failsafe Braking<\/h2>\n

Every crawler crane track drive contains an integrated parking brake \u2014 typically a spring-applied, hydraulically released multi-disc brake positioned at the high-speed (motor) end of the planetary gear train. This brake is not optional. It is a safety-critical component governed by crane standards (EN 13000, ASME B30.5) that must hold the crane stationary on the maximum expected gradient with no hydraulic power applied.<\/p>\n

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Spring-Applied Principle<\/div>\n

The brake springs engage the brake discs when hydraulic pressure is released \u2014 including during engine failure, hydraulic line rupture, or power loss. The brake engages automatically upon loss of pressure. This is a failsafe design: the default state is “brakes on.” The operator must actively apply hydraulic pressure to release the brake before the crane can travel.<\/p>\n<\/div>\n

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High-Speed Location Advantage<\/div>\n

Positioning the brake at the motor (high-speed) end of the planetary reduction multiplies the brake holding torque by the gear ratio. A brake producing 400 Nm of holding torque at the motor shaft, through a 200:1 planetary reduction, provides 80,000 Nm of holding torque at the sprocket \u2014 sufficient for a 200-tonne crane on a 5% slope. This arrangement minimises the brake physical size.<\/p>\n<\/div>\n

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Wear and Inspection<\/div>\n

Because the crane travels so infrequently (1 to 3% duty cycle), the brake discs experience minimal rotational wear. The primary wear mechanism is static holding \u2014 the brake discs can develop adhesion patterns from prolonged clamping in one position. Annual inspection should verify free release (no sticking), disc thickness measurement, and spring force verification.<\/p>\n<\/div>\n<\/div>\n<\/section>\n

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Three Failure Modes Specific to Crawler Crane Track Drives<\/h2>\n
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1<\/div>\n
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Parking brake disc adhesion from prolonged static clamping<\/div>\n

The crane sits stationary for 95 to 99% of its operating life with the parking brake engaged. Over months of continuous clamping at the same position, the brake disc friction material can bond to the reaction plate through a combination of moisture, heat cycling, and surface chemistry. When the operator commands travel, the brake does not release cleanly \u2014 the crane lurches or fails to move until the adhesion bond breaks. This sudden release produces a jolt that can initiate pendulum swing in any suspended rigging.<\/p>\n

Prevention: Cycle the parking brake (release and re-engage) weekly during prolonged stationary periods. Verify free release before every travel movement.<\/div>\n<\/div>\n<\/div>\n
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2<\/div>\n
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Ground subsidence overloading one track drive asymmetrically<\/div>\n

On unprepared or poorly compacted ground, one crawler can sink more than the other \u2014 shifting 55 to 70% of the total machine weight onto a single track drive. The overloaded drive carries up to 1.4 times its nominal share of the weight, while the other drive is underloaded. If the overloaded drive was sized for symmetric 50\/50 weight distribution, it operates at 140% of its rated torque during travel. Over multiple travel events on poor ground, the overloaded drive accumulates fatigue damage while the opposite drive remains within limits.<\/p>\n

Prevention: Verify ground compaction before travel. Use timber crane mats on soft ground. Size track drives for 1.4x asymmetric loading factor on unprepared ground.<\/div>\n<\/div>\n<\/div>\n
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3<\/div>\n
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Oil stagnation and moisture accumulation during prolonged stationary periods<\/div>\n

A track drive that sits stationary for weeks or months \u2014 common on project sites between crane mobilisations \u2014 does not circulate its gear oil. Moisture condensation accumulates in the housing during day-night thermal cycling. The oil at the bottom of the housing absorbs water while the upper gears and bearings are dry. When the crane finally travels, the initial rotation distributes the water-contaminated oil to the bearings, accelerating corrosion. On cranes stored outdoors in humid climates, this condensation-corrosion cycle is the leading cause of track drive bearing failure that occurs within the first 100 hours of operation after a storage period.<\/p>\n

Prevention: Change the track drive oil before re-mobilisation if the crane has been stationary for more than 3 months. Rotate the sprocket by hand monthly during storage to redistribute oil.<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/section>\n
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Korea Ever-Power Track Drives for Crawler Crane Applications<\/h2>\n
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\"Track<\/p>\n
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Crawler Crane Track Drives \u2192<\/a><\/div>\n

40,000 to 700,000 Nm output torque with integrated spring-applied parking brakes. Ratios 150:1 to 300:1 for controlled ultra-low-speed travel. Duo-cone sealed, oil-bath lubricated, with extended storage oil specifications.<\/p>\n<\/div>\n<\/div>\n

\"Winch<\/p>\n
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Winch Drive for Crane Hoisting \u2192<\/a><\/div>\n

The main hoist, auxiliary hoist, and boom hoist winch drives. Paired with the track drive and slewing drive to form the complete crawler crane drivetrain from a single supplier.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/section>\n

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Track Drive Planetary Gearbox for Crawler Cranes \u2014 Frequently Asked Questions<\/h2>\n
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Why do crawler crane track drives use much higher gear ratios than excavator track drives?<\/h3>\n

Crawler cranes travel at 0.7 to 1.5 km\/h \u2014 roughly one-quarter the speed of an excavator. The lower speed requires a higher gear ratio to match the hydraulic motor speed (2,000 to 3,000 rpm) to the required sprocket speed (2 to 5 rpm). A typical crane track drive ratio of 200:1 converts 2,500 rpm motor speed to 12.5 rpm at the sprocket, producing a travel speed of approximately 1.1 km\/h on a 900 mm PCD sprocket. The higher ratio also multiplies the motor torque by a larger factor \u2014 delivering the 80,000 to 700,000 Nm that these heavy machines require from a standard-sized hydraulic motor.<\/p>\n<\/div>\n

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How often should crawler crane track drive oil be changed?<\/h3>\n

Based on operating hours: every 1,000 to 2,000 hours. But for crawler cranes, calendar-based intervals are more relevant because the machine may accumulate only 200 to 500 travel hours per year. Recommended calendar interval: every 12 months regardless of operating hours, or before re-mobilisation if the crane has been stationary for more than 3 months. The low operating hours mean the oil is not worn out mechanically \u2014 but it degrades from moisture condensation and oxidation during prolonged stationary periods. Always drain a sample before re-mobilisation and inspect for water contamination (milky appearance).<\/p>\n<\/div>\n

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Can a crawler crane travel on a 5% slope safely?<\/h3>\n

Most manufacturers limit travel gradient to 3 to 5% depending on machine configuration and ground conditions. The track drive planetary gearbox must provide sufficient torque to drive the crane uphill AND the parking brake must hold the crane on the slope if the engine stalls. At 5% gradient on a 260-tonne crane, the grade resistance per track is approximately 63,700 N (28,700 Nm at a 900 mm PCD sprocket). The brake must hold this force indefinitely. Before travelling on any slope, verify: (1) the ground bearing capacity exceeds the static GBP plus dynamic amplification, (2) the track drive torque accommodates the gradient force plus rolling resistance, and (3) the parking brake is verified functional.<\/p>\n<\/div>\n

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What is the typical service life of a crawler crane track drive?<\/h3>\n

Crawler crane track drives last 15,000 to 25,000 operating hours \u2014 significantly longer than excavator or bulldozer track drives \u2014 because the duty cycle is so low. At 200 to 500 travel hours per year, this translates to 30 to 50+ years of calendar life. The practical life limiter is not gear wear but seal degradation, moisture-induced bearing corrosion during storage, and parking brake disc condition. Proactive oil management during stationary periods is the single most impactful maintenance activity for extending crawler crane track drive service life.<\/p>\n<\/div>\n

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Does Korea Ever-Power supply track drives with integrated spring-applied parking brakes?<\/h3>\n

Yes. Korea Ever-Power crawler crane track drive planetary gearboxes include spring-applied, hydraulically released multi-disc parking brakes as standard for crane applications. The brake is positioned at the motor (high-speed) end of the planetary train and is sized for the specific crane weight class and maximum gradient specified by the crane manufacturer. Brake holding torque, spring force, and disc material are matched to each track drive model. Provide the crane manufacturer, model, and maximum gradient for a verified brake specification.<\/p>\n<\/div>\n<\/div>\n<\/section>\n

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Crawler Crane Track Drives \u2014 Engineered for Weight, Not Speed<\/div>\n

Korea Ever-Power provides crawler crane track drive planetary gearboxes with integrated parking brakes from 40,000 to 700,000 Nm \u2014 covering 50-tonne lattice boom cranes through the largest 750-tonne heavy-lift machines. Provide your crane model and maximum travel gradient for a verified specification at no charge.<\/p>\n<\/div>\n

View Track Drive Range \u2192<\/a><\/p>\n
sales@planetary-gearboxes.com<\/div>\n<\/div>\n<\/div>\n<\/section>\n

Toimittaja: Cxm<\/p>\n<\/div>","protected":false},"excerpt":{"rendered":"

Application Engineering Crawler Cranes Track Drive Planetary Gearbox for Crawler Cranes \u2014 Moving 500 Tonnes at Walking Speed A bulldozer pushes hard and fast. An excavator pivots and repositions. A crawler crane does neither. It carries \u2014 slowly, deliberately, with absolute control \u2014 the heaviest single load that any self-propelled tracked machine places on the […]<\/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-1034","post","type-post","status-publish","format-standard","hentry","category-application-and-technical-guid"],"_links":{"self":[{"href":"https:\/\/planetary-gearboxes.com\/fi\/wp-json\/wp\/v2\/posts\/1034","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/planetary-gearboxes.com\/fi\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/planetary-gearboxes.com\/fi\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/planetary-gearboxes.com\/fi\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/planetary-gearboxes.com\/fi\/wp-json\/wp\/v2\/comments?post=1034"}],"version-history":[{"count":2,"href":"https:\/\/planetary-gearboxes.com\/fi\/wp-json\/wp\/v2\/posts\/1034\/revisions"}],"predecessor-version":[{"id":1037,"href":"https:\/\/planetary-gearboxes.com\/fi\/wp-json\/wp\/v2\/posts\/1034\/revisions\/1037"}],"wp:attachment":[{"href":"https:\/\/planetary-gearboxes.com\/fi\/wp-json\/wp\/v2\/media?parent=1034"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/planetary-gearboxes.com\/fi\/wp-json\/wp\/v2\/categories?post=1034"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/planetary-gearboxes.com\/fi\/wp-json\/wp\/v2\/tags?post=1034"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}