{"id":1922,"date":"2026-04-17T03:47:00","date_gmt":"2026-04-17T03:47:00","guid":{"rendered":"https:\/\/worm-reducers.xyz\/?p=1922"},"modified":"2026-04-17T03:48:26","modified_gmt":"2026-04-17T03:48:26","slug":"worm-gear-reducer-overheating-causes-calculation-fixes","status":"publish","type":"post","link":"https:\/\/worm-reducers.xyz\/zh\/worm-gear-reducer-overheating-causes-calculation-fixes\/","title":{"rendered":"\u8717\u8f6e\u51cf\u901f\u5668\u8fc7\u70ed\uff1a\u539f\u56e0\u3001\u8ba1\u7b97\u53ca\u89e3\u51b3\u65b9\u6cd5"},"content":{"rendered":"
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Worm Gear Reducer Overheating: Causes, Calculation & Fixes<\/h1>\n

Overheating is the most common cause of premature failure in \u8717\u8f6e\u51cf\u901f\u5668<\/strong> running continuous duty \u2014 and in most cases it was predictable and preventable at the selection stage. This guide gives you the thermal power calculation method and the six solutions for when the numbers don’t work.<\/p>\n

\u83b7\u53d6\u6280\u672f\u652f\u6301<\/a><\/p>\n<\/div>\n<\/div>\n

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The Core Problem: Efficiency Losses Become Heat<\/h2>\n
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\u4e00\u4e2a \u8717\u8f6e\u51cf\u901f\u5668<\/strong> at 40:1 reduction runs at roughly 60\u201368% efficiency. That means 32\u201340% of the input power is converted to heat inside the housing. At 5.5 kW input, that is 1.76\u20132.2 kW of continuous heat generation \u2014 equivalent to a 2 kW electric heater running inside a metal box the size of a toaster.<\/p>\n

Whether the \u8717\u8f6e\u51cf\u901f\u5668<\/strong> housing temperature stabilizes at an acceptable level or keeps climbing depends on a single balance: heat generated \u2264 heat dissipated<\/strong>. When heat generation exceeds the housing’s ability to dissipate through convection and radiation, temperature rises until something gives \u2014 usually the oil seal, the lubricant viscosity, or eventually the bearing preload.<\/p>\n

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The thermal power rating (P_th) in the datasheet is the maximum continuous input power at which this heat balance holds under standardized conditions (typically 20\u00b0C ambient, still air, horizontal mounting). Operating outside these conditions \u2014 higher ambient, enclosed installation, vertical mounting, full duty \u2014 reduces the effective thermal power rating.<\/p>\n<\/div>\n<\/div>\n<\/div>\n

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Thermal Power Rating vs Mechanical Power Rating<\/h2>\n

Most engineers are familiar with the mechanical power rating \u2014 the torque and speed the gears can physically transmit without tooth fracture or surface fatigue. The thermal power rating is a different and often more restrictive limit. It is the maximum continuous input power at which the housing surface temperature stabilizes below the maximum allowable limit (~80\u00b0C surface temperature in standard conditions).<\/p>\n

\n\n\n\n\n\n\n\n\n
\u8303\u56f4<\/th>\nMechanical Power Rating P_mech<\/th>\nThermal Power Rating P_th<\/th>\n<\/tr>\n<\/thead>\n
Governs<\/td>\nGear tooth stress, bearing load<\/td>\nHousing surface temperature under steady-state operation<\/td>\n<\/tr>\n
Relevant when<\/td>\nPeak torque and short-duration overloads<\/td>\nContinuous-duty operation at any load<\/strong><\/td>\n<\/tr>\n
Which is typically lower?<\/td>\nUsually higher \u2014 designed with safety margin<\/td>\nOften the active constraint for continuous duty<\/strong><\/td>\n<\/tr>\n
Affected by ambient temp?<\/td>\n\u4e0d<\/td>\nYes \u2014 significantly<\/strong><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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The most common selection error:<\/strong> Choosing a \u8717\u8f6e\u51cf\u901f\u5668<\/strong> where the mechanical power rating comfortably exceeds the application requirement, but the thermal power rating at actual ambient temperature falls below the continuous input power. The unit runs fine under intermittent load but overheats under continuous operation \u2014 and the cause is never immediately obvious from the catalog page.<\/p>\n<\/div>\n<\/div>\n

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The Four Variables That Determine Your Actual Thermal Power Limit<\/h2>\n
\n\n\n\n\n\n\n\n\n\n\n
Ambient \u00b0C<\/th>\nP_th Factor<\/th>\n<\/tr>\n<\/thead>\n
20\u00b0C<\/td>\n1.00 (catalog value)<\/td>\n<\/tr>\n
25\u00b0C<\/td>\n0.93<\/td>\n<\/tr>\n
30\u00b0C<\/td>\n0.87<\/td>\n<\/tr>\n
35\u00b0C<\/td>\n0.80<\/td>\n<\/tr>\n
40\u00b0C<\/td>\n0.73<\/td>\n<\/tr>\n
45\u00b0C<\/td>\n0.67<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Variable 1: Ambient Temperature<\/h3>\n

The catalog P_th is specified at 20\u00b0C ambient. Each 10\u00b0C rise in ambient temperature reduces the available thermal power by approximately 8\u201312%. Korean industrial environments commonly reach 35\u201340\u00b0C in summer, and enclosed machine cabinets can add another 5\u201310\u00b0C.<\/p>\n<\/div>\n

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Variable 2: Mounting Position<\/h3>\n

Horizontal mounting (worm shaft horizontal, output shaft horizontal) maximizes natural convection airflow over the housing fins. Vertical mounting reduces the effective dissipation area. Installation inside an enclosure with little airflow can reduce P_th by 20\u201330% compared to free-air horizontal mounting.<\/p>\n

\u5f53 \u8717\u8f6e\u51cf\u901f\u5668<\/strong> must be installed in an enclosed cabinet or vertical position, reduce the catalog P_th by 15\u201325% before comparing to your actual input power requirement.<\/p>\n<\/div>\n

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Variable 3: Duty Cycle<\/h3>\n

The catalog thermal power rating for any \u8717\u8f6e\u51cf\u901f\u5668<\/strong> assumes continuous S1 duty (100% on-time). If the application runs intermittently \u2014 for example, 30 seconds on, 30 seconds off \u2014 the thermal power limit can be exceeded because the housing partially cools during the off period.<\/p>\n

Approximate correction:<\/strong> For intermittent S3 duty with duty cycle DC% and cycle time T_c, effective input power P_eff = P_peak \u00d7 \u221a(DC\/100). A unit running 40% duty at 4 kW peak has P_eff = 4 \u00d7 \u221a0.4 = 2.53 kW for thermal assessment.<\/p>\n<\/div>\n

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Variable 4: Housing Size<\/h3>\n

Larger \u8717\u8f6e\u51cf\u901f\u5668<\/strong> frame size \u2192 more housing surface area \u2192 better natural convection. An NMRV-090 dissipates significantly more heat per unit of internal friction than an NMRV-050 because its surface area is roughly 3\u00d7 larger.<\/p>\n

Aluminum housing on a \u8717\u8f6e\u51cf\u901f\u5668<\/strong> additionally has ~3\u00d7 higher thermal conductivity than cast iron, so NMRV aluminum units typically have higher P_th than WP cast iron units of equivalent frame size \u2014 despite the cast iron units having higher mechanical torque ratings.<\/p>\n<\/div>\n<\/div>\n<\/div>\n

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Thermal Power Verification \u2014 Complete Worked Example<\/h2>\n

\u5e94\u7528\uff1a<\/strong> Continuous-duty conveyor drive, 8 hours\/day. Required \u8717\u8f6e\u51cf\u901f\u5668<\/strong> output torque: 220 N\u00b7m at 36 rpm output. Motor runs at 1,440 rpm. Ambient temperature: 35\u00b0C. Horizontal installation, partially enclosed (reduce P_th by 15%).<\/p>\n

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Step 1 \u2014 Required reduction ratio:<\/strong>
\ni = 1,440 \/ 36 = 40:1<\/strong><\/p>\n

Step 2 \u2014 Efficiency at 40:1:<\/strong>
\n\u03b7 \u2248 0.64 (from efficiency-ratio table)<\/p>\n

Step 3 \u2014 Required input power:<\/strong>
\nP_input = (T \u00d7 n) \/ (9,550 \u00d7 \u03b7)
\nP_input = (220 \u00d7 36) \/ (9,550 \u00d7 0.64)
\nP_input = 7,920 \/ 6,112 = 1.30 kW<\/strong><\/p>\n

Step 4 \u2014 Apply service factor (moderate shock, 8h\/day, SF = 1.5):<\/strong>
\nP_design = 1.30 \u00d7 1.5 = 1.95 kW input<\/strong><\/p>\n<\/div>\n

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Step 5 \u2014 Candidate \u8717\u8f6e\u51cf\u901f\u5668<\/strong> unit:<\/strong> NMRV-063 at 40:1
\nCatalog P_th at 20\u00b0C = 2.8 kW<\/strong><\/p>\n

Step 6 \u2014 Apply ambient correction (35\u00b0C, factor 0.80):<\/strong>
\nP_th (35\u00b0C) = 2.8 \u00d7 0.80 = 2.24 kW<\/strong><\/p>\n

Step 7 \u2014 Apply installation correction (enclosed, \u221215%):<\/strong>
\nP_th (corrected) = 2.24 \u00d7 0.85 = 1.90 kW<\/strong><\/p>\n

Step 8 \u2014 Check:<\/strong>
\nP_design (1.95 kW) > P_th corrected (1.90 kW)
\n\u2192 FAILS thermal check by a 3% margin.<\/span><\/p>\n

Resolution:<\/strong> Upgrade to NMRV-075 at 40:1 (P_th catalog = 3.9 kW) \u2014 clears thermal limit with margin.<\/p>\n<\/div>\n<\/div>\n

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Key takeaway from this example:<\/strong> The NMRV-063 mechanical rating comfortably exceeds 1.95 kW input at 40:1. The thermal rating \u2014 adjusted for a Korean summer ambient of 35\u00b0C and partially enclosed installation \u2014 does not. Without the thermal check, this installation would produce a unit that overheats and fails within months despite being “within mechanical specification.”<\/p>\n<\/div>\n<\/div>\n

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Diagnosing Thermal Problems in the Field<\/h2>\n
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Measurement method:<\/strong> Use an infrared thermometer on the \u8717\u8f6e\u51cf\u901f\u5668<\/strong> housing surface. Measure at the geometric center of the housing (not near the output shaft or input flange), after the unit has been running at operating load for at least 30 minutes.<\/p>\n

\n\n\n\n\n\n\n\n\n
Housing Temp Rise
\n(above ambient)<\/th>\n		Assessment<\/th>\n\u884c\u52a8<\/th>\n<\/tr>\n<\/thead>\n
\u2264 40\u00b0C<\/td>\nNormal<\/td>\nNo action needed<\/td>\n<\/tr>\n
40\u201355\u00b0C<\/td>\nElevated<\/td>\nMonitor; check airflow and oil level<\/td>\n<\/tr>\n
55\u201365\u00b0C<\/td>\nCritical<\/td>\nImplement cooling improvement within 1 week<\/td>\n<\/tr>\n
> 65\u00b0C<\/td>\nOver-temperature<\/td>\nStop, diagnose, upgrade immediately<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

Note: Maximum allowable housing surface temperature is approximately 80\u201390\u00b0C for most worm gear reducers. These thresholds are based on temperature rise above ambient to catch problems before they approach the absolute limit.<\/p>\n<\/div>\n<\/div>\n<\/div>\n

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Six Cooling Solutions \u2014 With Implementation Cost and Expected Effect<\/h2>\n
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Solution 1: Reduce Duty Cycle<\/h3>\n

How:<\/strong> Add idle time between operating cycles to allow the housing to partially cool.<\/p>\n

Effect:<\/strong> Reduces effective thermal load proportional to duty cycle reduction. 20% duty cycle reduction \u2192 approximately 10\u201315% lower steady-state temperature.<\/p>\n

\u6210\u672c\uff1a<\/strong> Zero (process change only)<\/p>\n

When it works:<\/strong> Applications where cycle time is flexible \u2014 packaging, material handling, periodic positioning. Not applicable where continuous operation is required.<\/p>\n<\/div>\n

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Solution 2: Add an External Fan<\/h3>\n

How:<\/strong> Mount a 25\u201350W electric fan to blow directly over the housing surface. Orient to maximize airflow across the fin pattern.<\/p>\n

Effect:<\/strong> Forced convection increases heat transfer coefficient by 3\u20135\u00d7. Typical P_th improvement: 30\u201360% at 20\u00b0C ambient.<\/p>\n

\u6210\u672c\uff1a<\/strong> Low (fan + bracket)<\/p>\n

When it works:<\/strong> Most applications. One of the most cost-effective thermal improvements available for an existing installation. Fan should run whenever the reducer is running.<\/p>\n<\/div>\n

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Solution 3: Upgrade to a Larger Frame Size<\/h3>\n

How:<\/strong> Replace the current \u8717\u8f6e\u51cf\u901f\u5668<\/strong> with the next larger frame size at the same ratio. The larger housing has greater surface area and better natural heat dissipation.<\/p>\n

Effect:<\/strong> P_th typically increases by 40\u201370% per frame size step. Most reliable long-term fix.<\/p>\n

\u6210\u672c\uff1a<\/strong> Moderate (replacement unit + possible installation modification)<\/p>\n

When it works:<\/strong> Best solution when there is installation space available for the larger unit. Also provides additional torque margin.<\/p>\n<\/div>\n

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Solution 4: Improve Ambient Ventilation<\/h3>\n

How:<\/strong> Open or enlarge ventilation slots in the enclosure, relocate the reducer to a cooler zone, or add a heat exchanger for the enclosure air.<\/p>\n

Effect:<\/strong> Reduces effective ambient temperature. Every 5\u00b0C ambient reduction improves P_th by ~5\u20137%.<\/p>\n

\u6210\u672c\uff1a<\/strong> Low to moderate<\/p>\n

When it works:<\/strong> Best for installations in enclosed cabinets or hot rooms. Less effective if ambient is already close to outdoor temperature.<\/p>\n<\/div>\n

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Solution 5: Switch to Synthetic Lubricant<\/h3>\n

How:<\/strong> Replace mineral ISO VG 220 with synthetic PAO ISO VG 220. Synthetic oil has a lower friction coefficient at the worm-wheel interface \u2014 typically improving efficiency by 2\u20135 percentage points.<\/p>\n

Effect:<\/strong> At 40:1 (\u03b7 \u2248 64% mineral), synthetic oil may improve \u03b7 to 67\u201369%, reducing heat generation by ~8\u201312%.<\/p>\n

\u6210\u672c\uff1a<\/strong> Minimal (one oil change)<\/p>\n

When it works:<\/strong> Useful as a supplementary measure. Rarely sufficient alone to solve a significant thermal deficit, but always worth doing in borderline cases.<\/p>\n<\/div>\n

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Solution 6: Install an External Cooling Radiator<\/h3>\n

How:<\/strong> Attach an external oil radiator (either air-cooled or water-cooled) with a small pump circulating the oil between the reducer and the radiator. Available as retrofit kit for WP series units.<\/p>\n

Effect:<\/strong> Can handle 3\u20135\u00d7 the catalog P_th with an adequately sized radiator. Complete solution for severely thermally limited installations.<\/p>\n

\u6210\u672c\uff1a<\/strong> Higher<\/p>\n

When it works:<\/strong> When neither frame upgrade nor fan is feasible due to space constraints. High-torque continuous-duty applications like extruders and agitators.<\/p>\n<\/div>\n<\/div>\n<\/div>\n

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Special Cases: Glass Kilns, Metallurgy, and Drying Equipment<\/h2>\n
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\u5f53 \u8717\u8f6e\u51cf\u901f\u5668<\/strong> is \u8717\u8f6e\u51cf\u901f\u5668<\/strong> is installed adjacent to a heat source \u2014 glass annealing leher, metallurgical casting conveyor, kiln roller drive, food drying oven \u2014 ambient temperatures around the unit can reach 50\u201380\u00b0C continuously.<\/p>\n

At these ambient temperatures, standard mineral oil will oxidize rapidly and the viscosity-temperature relationship means lubrication becomes marginal. The correct approach is:<\/p>\n

1. Use synthetic PAO ISO VG 320 (higher viscosity than standard).<\/strong> At elevated temperature, the oil thins significantly \u2014 starting at VG 320 ensures adequate viscosity at operating temperature.<\/p>\n

2. Install a thermal insulation barrier<\/strong> between the heat source and the \u8717\u8f6e\u51cf\u901f\u5668<\/strong> housing. Even a simple sheet metal heat shield with air gap significantly reduces the effective ambient seen by the unit.<\/p>\n

3. Reduce oil change interval to 500\u2013800 hours<\/strong> in high-temperature environments, regardless of the oil’s appearance. High-temperature oxidation degrades base oil without visible color change \u2014 an oil analysis program is the most accurate indicator of change timing.<\/p>\n

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Frequently Asked Questions \u2014 Worm Gear Reducer Thermal Management<\/h2>\n
\nWhere should I point the infrared thermometer on the housing?<\/summary>\n
Measure at the geometric center of the housing body \u2014 not at the output shaft end (which runs hotter due to proximity to the gear mesh) and not at the input end (which runs cooler as it is further from the heat source). On a standard NMRV unit, this is approximately the mid-point of the housing face opposite the output shaft. Take at least three readings at 5-minute intervals after the unit has been running under load for 30+ minutes and confirm the temperature has stabilized before drawing conclusions.<\/div>\n<\/details>\n
\nThe unit runs fine in winter but overheats in summer \u2014 is this a thermal power problem?<\/summary>\n
Yes, this is a classic thermal power margin problem. The \u8717\u8f6e\u51cf\u901f\u5668<\/strong> is operating near its corrected thermal limit at summer ambient (~35\u00b0C in Korea) but comfortably within it at winter ambient (~10\u00b0C). The correct fix is to add an external fan (quickest solution) or upgrade to the next frame size if this is a permanent installation. A fan running during the warm season and disabled during winter is a practical intermediate solution if the motor control system allows it.<\/div>\n<\/details>\n
\nCan switching to synthetic oil really solve an overheating problem?<\/summary>\n
Synthetic oil alone rarely solves a significant overheating problem, but it meaningfully reduces heat generation. At 40:1 ratio with mineral oil at \u03b7 \u2248 64%, switching to PAO synthetic may improve \u03b7 to 67\u201368%. This reduces heat generation from 36% of input power to 32\u201333% \u2014 a reduction of about 3 kW for every 10 kW input. In a borderline case where the unit is 5\u201310% over its thermal limit, this is often enough to bring it back within range. For a unit running significantly over its thermal power limit, synthetic oil alone is not sufficient \u2014 a fan or frame upgrade is needed in addition.<\/div>\n<\/details>\n
\nWhich direction should an external fan blow \u2014 toward the worm shaft end or the output shaft end?<\/summary>\n
Direct the fan to blow across the widest housing face \u2014 typically the side face of the gearbox body. The goal is maximum airflow across the largest available surface area. The direction relative to worm or output shaft matters less than achieving high air velocity over the finned housing surfaces. If the housing has cooling fins, orient airflow parallel to the fins to minimize resistance. A 200 mm diameter industrial fan at 2 m\/s airflow over the housing surface is sufficient for most standard NMRV units up to frame 090.<\/div>\n<\/details>\n
\nThe housing is still hot after shutdown \u2014 is this normal?<\/summary>\n
Yes, entirely normal. The housing metal has significant thermal mass and takes 20\u201340 minutes to cool to ambient temperature after shutdown. What is not normal is a housing that is still hotter after shutdown than it was 5 minutes into operation \u2014 that would suggest the lubrication system is not circulating heat away from the gear mesh effectively. For standard continuous-duty \u8717\u8f6e\u51cf\u901f\u5668<\/strong>, peak housing temperature is typically reached within 45\u201390 minutes of startup under load, after which temperature stabilizes until shutdown.<\/div>\n<\/details>\n
\nCan a thermal protection sensor be mounted on the worm gear reducer housing?<\/summary>\n
Yes, and this is a practical approach for high-duty-cycle installations. A surface-mount thermocouple or PT100 sensor bonded to the housing mid-face provides a continuous temperature reading that can trigger an alarm or motor shutdown when the housing surface exceeds a set threshold (typically 75\u201380\u00b0C). This provides protection against seasonal variation, unexpected load increases, and cooling system failures. The sensor is not a substitute for correct thermal sizing \u2014 it is a safety backstop for a properly selected unit. Contact \u97e9\u56fd\u6c38\u529b<\/a> for thermal monitoring guidance for specific applications.<\/div>\n<\/details>\n<\/div>\n

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Thermal Sizing Support for Your Application<\/h2>\n

\u4f5c\u4e3a\u4e00\u540d\u4e13\u5bb6 \u8717\u8f6e\u51cf\u901f\u5668\u4f9b\u5e94\u5546<\/a>, Korea Ever-Power’s engineering team can perform a thermal power verification for your specific worm gear reducer application \u2014 including ambient correction, installation factor, and duty cycle assessment. Send us your duty parameters and we will confirm whether your current or planned selection has adequate thermal margin.<\/p>\n

\u6d4f\u89c8\u8717\u8f6e\u51cf\u901f\u5668<\/a>
\nRequest Thermal Assessment<\/a><\/div>\n<\/div>\n

\u7f16\u8f91\uff1aCxm<\/p>\n<\/div>","protected":false},"excerpt":{"rendered":"

Worm Gear Reducer Overheating: Causes, Calculation & Fixes Overheating is the most common cause of premature failure in worm gear reducers running continuous duty \u2014 and in most cases it was predictable and preventable at the selection stage. This guide gives you the thermal power calculation method and the six solutions for when the numbers […]<\/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":[1517],"tags":[],"class_list":["post-1922","post","type-post","status-publish","format-standard","hentry","category-worm-gear-reducer"],"_links":{"self":[{"href":"https:\/\/worm-reducers.xyz\/zh\/wp-json\/wp\/v2\/posts\/1922","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/worm-reducers.xyz\/zh\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/worm-reducers.xyz\/zh\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/worm-reducers.xyz\/zh\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/worm-reducers.xyz\/zh\/wp-json\/wp\/v2\/comments?post=1922"}],"version-history":[{"count":4,"href":"https:\/\/worm-reducers.xyz\/zh\/wp-json\/wp\/v2\/posts\/1922\/revisions"}],"predecessor-version":[{"id":1926,"href":"https:\/\/worm-reducers.xyz\/zh\/wp-json\/wp\/v2\/posts\/1922\/revisions\/1926"}],"wp:attachment":[{"href":"https:\/\/worm-reducers.xyz\/zh\/wp-json\/wp\/v2\/media?parent=1922"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/worm-reducers.xyz\/zh\/wp-json\/wp\/v2\/categories?post=1922"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/worm-reducers.xyz\/zh\/wp-json\/wp\/v2\/tags?post=1922"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}