{"id":711,"date":"2026-06-01T05:44:26","date_gmt":"2026-06-01T05:44:26","guid":{"rendered":"https:\/\/planetary-gearboxes.com\/?p=711"},"modified":"2026-06-01T05:44:26","modified_gmt":"2026-06-01T05:44:26","slug":"planetary-gearbox-maintenance-inspection-guide","status":"publish","type":"post","link":"https:\/\/planetary-gearboxes.com\/ko\/planetary-gearbox-maintenance-inspection-guide\/","title":{"rendered":"\uc720\uc131 \uae30\uc5b4\ubc15\uc2a4 \uc720\uc9c0\ubcf4\uc218 \ubc0f \uc810\uac80 \uc548\ub0b4\uc11c"},"content":{"rendered":"
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Maintenance Reference \u00b7 12-Point Checklist \u00b7 Measurement Procedure \u00b7 Grease Life Model<\/div>\n

Planetary Gearbox Maintenance Guide \u2014
\n12-Point Inspection and Service Schedule<\/h1>\n

Most Korean factories perform no planned maintenance on sealed planetary gearboxes because there is nothing to lubricate or adjust \u2014 and that is almost correct. The one irreplaceable maintenance activity<\/strong> is annual backlash measurement against the delivery certificate baseline: the only reliable early indicator of wear accumulation that, if tracked over three years, predicts the replacement window before the gearbox fails in production.<\/p>\n

EP-AB \uc815\ubc00 \uc2dc\ub9ac\uc988 \ubcf4\uae30 \u2192
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What “Sealed for Life” Actually Means \u2014 and What Maintenance Remains Required<\/h2>\n
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Korea Ever-Power EP series gearboxes use permanently sealed grease that eliminates the lubrication maintenance that dominates the service schedule for oil-bath and open-gear reducers. This is a genuine operational advantage \u2014 no oil level checks, no oil changes, no fill\/drain procedures. But “sealed for life” does not mean “maintenance-free for life.” Three maintenance activities remain essential for Korea Ever-Power EP series gearboxes throughout their service life.<\/p>\n

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\u2460 Annual backlash measurement<\/div>\n

The single most valuable maintenance activity \u2014 measures gear tooth wear over time. Compare to delivery certificate value annually. The growth curve over 3\u20135 measurements predicts replacement window with 6\u201312 months advance notice. Takes 10 minutes, requires only a dial gauge and a locked input shaft.<\/p>\n<\/div>\n

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\u2461 Annual shaft seal inspection<\/div>\n

A failed shaft seal allows grease to exit and contaminants to enter \u2014 the fastest path to premature gearbox failure. Visual inspection for grease residue on the output shaft or housing face takes 2 minutes. Any visible grease weeping indicates seal wear \u2014 schedule replacement before the next planned shutdown.<\/p>\n<\/div>\n

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\u2462 Annual steady-state temperature baseline<\/div>\n

Record housing temperature at normal operating load with an infrared thermometer. A year-on-year temperature rise of 5\u00b0C or more at the same load indicates grease degradation beginning. Consistent with Art13 thermal analysis \u2014 early warning before overheating symptoms become acute.<\/p>\n<\/div>\n<\/div>\n

Everything else \u2014 housing cleaning, fastener torque checks, noise baseline recording, mounting alignment verification \u2014 is secondary but contributes to the complete annual inspection picture. The 12-point checklist in Module 4 captures all relevant inspection items in one printable document.<\/p>\n<\/div>\n

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EP Series \u2014 What Maintenance Is and Is NOT Required<\/p>\n

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NOT required (sealed grease construction):<\/strong><\/p>\n

\u2717 Re-greasing or adding grease
\n\u2717 Oil level checks or oil changes
\n\u2717 Vent plug cleaning or replacement
\n\u2717 Fill\/drain port servicing
\n\u2717 Grease type specification<\/div>\n<\/div>\n
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Required (annual):<\/strong><\/p>\n

\u2713 Backlash measurement (10 min)
\n\u2713 Shaft seal visual inspection (2 min)
\n\u2713 Housing temperature baseline (5 min)
\n\u2713 Mounting bolt torque check (5 min)
\n\u2713 Noise\/vibration baseline (5 min)
\n\u2713 Coupling\/shaft alignment verify (10 min)<\/div>\n<\/div>\n<\/div>\n

Total annual inspection time: approximately 40 minutes per gearbox. In a 100-machine Korean factory: ~67 person-hours per year.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/section>\n

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Backlash Measurement Procedure \u2014 Step-by-Step Field Protocol<\/h2>\n
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Annual backlash measurement is the cornerstone of the planetary gearbox maintenance guide for any Korean precision servo application. The procedure requires no special tools beyond a dial gauge, a magnetic base, and a torque wrench \u2014 equipment available in virtually every Korean factory maintenance department.<\/p>\n

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1<\/div>\n

De-energise and lock the drive system<\/strong><\/p>\n<\/div>\n

Switch off power to the servo drive. Engage the motor holding brake (if fitted) or physically lock the motor shaft \u2014 a shaft clamp or wooden block prevents any input shaft rotation during measurement. Confirm zero energy state per your factory LOTO (lockout\/tagout) procedure before approaching the gearbox output.<\/p>\n<\/div>\n

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2<\/div>\n

Mount the dial gauge at the output shaft<\/strong><\/p>\n<\/div>\n

Attach the magnetic base to a fixed machine surface (not the gearbox housing). Position the dial gauge plunger tangentially against the output shaft flange or coupling at a known radius r from the shaft centreline. Record this radius \u2014 it is needed to convert the linear gauge reading to angular backlash in arcminutes: \u03b8 (arcmin) = (\u0394x \/ r) \u00d7 (180 \u00d7 60 \/ \u03c0) = (\u0394x \/ r) \u00d7 3,438.<\/p>\n<\/div>\n

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3<\/div>\n

Apply light torque and zero the gauge<\/strong><\/p>\n<\/div>\n

Apply a small torque (approximately 5% of rated torque) to the output shaft in one direction using a torque wrench on the output flange. This preloads the gear teeth against one set of flanks and eliminates any position uncertainty. Zero the dial gauge at this loaded position.<\/p>\n<\/div>\n

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4<\/div>\n

Reverse torque and read displacement<\/strong><\/p>\n<\/div>\n

Apply the same small torque in the opposite direction. The gauge will move from zero to a new position. The total displacement \u0394x (mm) is the linear backlash at radius r. Convert to arcminutes using the formula in Step 2. Record the value and the measurement date.<\/p>\n<\/div>\n

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5<\/div>\n

Compare to delivery certificate and trend<\/strong><\/p>\n<\/div>\n

Compare the measured value to the delivery certificate baseline (e.g. “0.82 arcmin, delivered 15 March 2023”). Record both in your maintenance log. If three consecutive annual measurements show a consistent upward trend, extrapolate to the 2\u00d7 delivery value threshold \u2014 this is the predicted replacement date. For example: Year 1: 0.82′, Year 2: 1.05′, Year 3: 1.28′ \u2192 trend of +0.23’\/yr \u2192 reach 1.64′ (2\u00d7) in Year 4.5 \u2192 plan replacement in Year 4 maintenance window.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n

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Gauge Reading \u2192 Arcminute Conversion Reference<\/p>\n

Formula: \u03b8 (arcmin) = (\u0394x \u00f7 r) \u00d7 3,438 \u00b7 r in mm \u00b7 \u0394x = total gauge travel from one side of backlash to the other<\/p>\n

\n\n\n\n\n\n\n\n\n
Measurement radius r<\/th>\n\u0394x = 0.03 mm<\/th>\n\u0394x = 0.05 mm<\/th>\n\u0394x = 0.10 mm<\/th>\n\u0394x = 0.15 mm<\/th>\n<\/tr>\n<\/thead>\n
r = 25 mm (small coupling)<\/td>\n4.1′<\/td>\n6.9′<\/td>\n13.8′<\/td>\n20.6′<\/td>\n<\/tr>\n
r = 50 mm (100mm OD coupling)<\/td>\n2.1′<\/td>\n3.4′<\/td>\n6.9′<\/td>\n10.3′<\/td>\n<\/tr>\n
r = 100 mm (flange \/ arm)<\/td>\n1.0′<\/td>\n1.7′<\/td>\n3.4′<\/td>\n5.2′<\/td>\n<\/tr>\n
r = 150 mm (large flange)<\/td>\n0.7′<\/td>\n1.1′<\/td>\n2.3′<\/td>\n3.4′<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
Practical tip \u2014 use the coupling OD as your measurement surface: <\/strong>
\nA 100 mm jaw-coupling OD gives r = 50 mm. At this radius, 1 arcmin = 0.029 mm of gauge travel \u2014 readable with a standard 0.01 mm dial gauge. Highlight the r = 50 mm row above for the most common Korean packaging and conveyor coupling size.<\/span><\/div>\n<\/div>\n<\/section>\n

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Grease Life Model \u2014 Predicting Service Life from Temperature, Speed, and Load<\/h2>\n
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The standard 20,000-hour design life for Korea Ever-Power EP sealed grease assumes operation within rated parameters at the reference temperature. When actual operating conditions differ from the reference, grease life adjusts according to three variables: housing temperature, input speed, and applied torque as a fraction of rated torque.<\/p>\n

Temperature factor (dominant):<\/strong> As established in the Arrhenius model (Art13), grease oxidation rate doubles for every 10\u00b0C above rated temperature. The grease life correction factor for temperature:<\/p>\n

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GREASE LIFE \u2014 THREE-VARIABLE MODEL<\/p>\n

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L_actual = L_base \u00d7 f_T \u00d7 f_n \u00d7 f_L<\/p>\n

f_T (temperature):
\nf_T = 2^((T_ref \u2212 T_actual)\/10)
\nAt T=70\u00b0C (ref): f_T = 1.0
\nAt T=80\u00b0C: f_T = 0.5
\nAt T=90\u00b0C: f_T = 0.25<\/p>\n

f_n (speed, relative to rated):
\nAt n = n_rated: f_n = 1.0
\nAt n = 1.5\u00d7rated: f_n = 0.7
\nAt n = 0.5\u00d7rated: f_n = 1.3<\/p>\n

f_L (load, relative to rated):
\nAt L = 100% T_rated: f_L = 1.0
\nAt L = 70% T_rated: f_L = 1.25
\nAt L = 130% T_rated: f_L = 0.7<\/p>\n

Example \u2014 Korean summer packaging drive:
\nT=82\u00b0C, n=1.0\u00d7, L=90%
\nf_T=0.45, f_n=1.0, f_L=0.95
\nL = 20,000 \u00d7 0.45 \u00d7 1.0 \u00d7 0.95
\n= 8,550 hours (vs 20,000 rated)<\/span><\/p>\n<\/div>\n<\/div>\n

This example illustrates a critical planning point for Korean food packaging facilities: a gearbox running at 82\u00b0C in summer conditions (typical for an uncooled packaging hall in August) has an actual grease life of 8,550 hours \u2014 not the 20,000 hours stated in the datasheet. At 6,300 operating hours per year in three-shift operation, this gearbox should be replaced at 16 months, not the 38 months implied by the rated life.<\/p>\n

The practical application: measure housing temperature during peak summer operation (July\u2013August) and apply the temperature correction factor to calculate the actual grease life for your specific installation. Then plan replacement accordingly \u2014 a 12-month notice period allows spare gearbox inventory to be organised without emergency procurement costs.<\/p>\n<\/div>\n<\/div>\n<\/section>\n<\/div>\n

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Grease Life at Different Operating Conditions (based on L_base = 20,000 h)<\/p>\n

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Conditions<\/th>\n\uc0b6<\/th>\n3-shift replace<\/th>\n<\/tr>\n<\/thead>\n
T=65\u00b0C, 80% load<\/td>\n26,000 h<\/td>\n4.1 yr<\/td>\n<\/tr>\n
T=70\u00b0C, 100% load (ref)<\/td>\n20,000\uc2dc\uac04<\/td>\n3.2 yr<\/td>\n<\/tr>\n
T=80\u00b0C, 100% load<\/td>\n10,000 h<\/td>\n1.6 yr<\/td>\n<\/tr>\n
T=82\u00b0C, 90% load (summer)<\/td>\n8,550 h<\/td>\n1.4 yr<\/td>\n<\/tr>\n
T=90\u00b0C, 100% load<\/td>\n5,000 h<\/td>\n0.8 yr<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

3-shift = 6,300 h\/yr. Temperature is dominant variable \u2014 10\u00b0C rise halves service life.<\/p>\n<\/div>\n<\/div>\n

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12-Point Annual Inspection Checklist \u2014 Printable Field Reference<\/h2>\n

Complete this inspection at each annual planned maintenance shutdown. This planetary gearbox maintenance guide inspection form records all values in one place. The quantified trigger values define the action: “Schedule replacement” = plan at next shutdown; “STOP” = take offline immediately.<\/p>\n

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Korea Ever-Power EP Series \u2014 Annual Inspection Record<\/span>
\nMachine: ________ \u00b7 Date: ________ \u00b7 Inspector: ________<\/span><\/div>\n
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#<\/th>\nInspection Item<\/th>\nMethod<\/th>\nSchedule Replacement<\/th>\nSTOP<\/th>\nRecorded Value<\/th>\n<\/tr>\n<\/thead>\n
1<\/td>\nOutput shaft backlash<\/td>\nDial gauge, locked input \u2014 Module 2 procedure<\/td>\n\u22651.5\u00d7 delivery cert.<\/td>\n\u22652\u00d7 delivery cert.<\/td>\n______ arcmin<\/td>\n<\/tr>\n
2<\/td>\nShaft seal \u2014 grease weeping<\/td>\nVisual \u2014 output shaft and housing face<\/td>\nAny grease on shaft<\/td>\nActive grease flow<\/td>\nPass \/ Fail<\/td>\n<\/tr>\n
3<\/td>\nHousing temperature (steady state)<\/td>\nIR thermometer, 20 min after normal start<\/td>\n+5\u00b0C vs prev. year<\/td>\n>90\u00b0C absolute<\/td>\n______ \u00b0C<\/td>\n<\/tr>\n
4<\/td>\n\uc791\ub3d9 \uc18c\uc74c \uc218\uc900<\/td>\nSmartphone dB meter at 300 mm, rated speed<\/td>\n+5 dB vs baseline<\/td>\n+10 dB or new tone<\/td>\n______ dB(A)<\/td>\n<\/tr>\n
5<\/td>\nVibration \u2014 housing RMS<\/td>\nAccelerometer at marked position on housing<\/td>\n2\u00d7 baseline RMS<\/td>\n5\u00d7 baseline or impulses<\/td>\n______ mm\/s<\/td>\n<\/tr>\n
6<\/td>\nMounting bolt torque<\/td>\nTorque wrench at specified value<\/td>\nAny bolt <80% spec<\/td>\nAny bolt loose\/missing<\/td>\nPass \/ Fail<\/td>\n<\/tr>\n
7<\/td>\nShaft coupling condition<\/td>\nVisual \u2014 jaw, spider element, clamping ring<\/td>\nCracking, deformation<\/td>\nFractured or loose<\/td>\nPass \/ Fail<\/td>\n<\/tr>\n
8<\/td>\nShaft alignment (motor\u2013gearbox)<\/td>\nDial gauge on coupling flange<\/td>\n>0.05 mm radial TIR<\/td>\n>0.15 mm radial TIR<\/td>\n______ mm<\/td>\n<\/tr>\n
9<\/td>\nInput shaft end-play<\/td>\nDial gauge axial on input shaft end<\/td>\n>0.05 mm axial<\/td>\n>0.15 mm axial<\/td>\n______ mm<\/td>\n<\/tr>\n
10<\/td>\nHousing surface condition<\/td>\nVisual \u2014 corrosion, impact damage<\/td>\nCorrosion >5% area<\/td>\nThrough-wall cracks<\/td>\nPass \/ Note<\/td>\n<\/tr>\n
11<\/td>\nOperating hours since installation<\/td>\nMachine controller log or estimate<\/td>\n\u226515,000 h<\/td>\n\u226520,000 h (overdue)<\/td>\n______ h<\/td>\n<\/tr>\n
12<\/td>\nGrease life \u2014 temperature-corrected<\/td>\nL_actual from Module 3 formula \u00d7 Item 3 temp<\/td>\nItem 11 \u2265 75% L_actual<\/td>\nItem 11 \u2265 L_actual<\/td>\n______ h remaining<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
Overall result:<\/strong> \u2610 No action \u00a0 \u2610 Schedule replacement \u00a0 \u2610 STOP \u2014 remove from service
\nNext inspection due:<\/strong> ________ (one year from today)<\/div>\n<\/div>\n<\/section>\n

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Temperature, Noise, and Vibration \u2014 Establishing Baselines and Reading Warning Signs<\/h2>\n

The value of temperature, noise, and vibration measurements comes not from absolute values alone but from trending<\/em> \u2014 how they change year-on-year at the same operating conditions. A gearbox at 73 dB(A) in Year 3 that was 68 dB(A) in Year 1 (same speed and load) has produced 5 dB(A) of noise growth signalling internal wear accumulation, regardless of whether 73 dB(A) exceeds any absolute limit.<\/p>\n

To establish meaningful baselines, all measurements must be taken at consistent conditions<\/strong>. For Korean factories the recommended baseline protocol is:<\/p>\n

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