{"id":263,"date":"2026-06-12T08:32:42","date_gmt":"2026-06-12T08:32:42","guid":{"rendered":"https:\/\/planetary-gearboxes.cn\/?p=263"},"modified":"2026-06-12T08:32:42","modified_gmt":"2026-06-12T08:32:42","slug":"inline-vs-right-angle-planetary-gearbox","status":"publish","type":"post","link":"https:\/\/planetary-gearboxes.cn\/ko\/inline-vs-right-angle-planetary-gearbox\/","title":{"rendered":"Inline vs Right-Angle Planetary Gearbox \u2014 Space, Precision, and Efficiency Trade-Offs Explained"},"content":{"rendered":"
\n\"Inline<\/p>\n
\n
CONFIGURATION COMPARISON<\/div>\n

Inline vs Right-Angle Planetary Gearbox<\/h1>\n

Same planetary gear train inside. Different motor orientation outside. That 90-degree bend costs you 2% efficiency and 5\u20138 arcmin of backlash \u2014 but it saves 40\u201350% of the installation depth behind the output face. Here is exactly when each trade-off is worth making.<\/p>\n

\n
\n
40\u201350%<\/div>\n
DEPTH REDUCTION<\/div>\n<\/div>\n
\n
~2%<\/div>\n
EFFICIENCY COST<\/div>\n<\/div>\n
\n
+5\u20138\u2032<\/div>\n
BACKLASH ADDED<\/div>\n<\/div>\n<\/div>\n

Help Me Choose the Right Configuration \u2192<\/a><\/p>\n<\/div>\n<\/div>\n

\n

<\/p>\n

What Differs Between Inline and Right-Angle Configurations?<\/h2>\n

Both configurations use the same fundamental planetary gear train \u2014 sun gear, planet gears, ring gear, and carrier. The difference is what happens at the input<\/strong> side of the assembly. This distinction seems minor on paper, but it cascades into meaningful differences in efficiency, backlash, noise, weight, cost, and installation envelope that determine whether each configuration is suitable for your specific application.<\/p>\n

\n
\n
\u25c6 Inline (Coaxial)<\/div>\n
The servo motor bolts directly to the input side of the planetary gear train. Motor shaft and output shaft share the same rotational axis<\/strong>. No additional gear stage is needed at the input \u2014 the motor drives the sun gear directly through a coupling sleeve.<\/p>\n

Result:<\/strong> Maximum efficiency, tightest backlash, lightest weight, lowest cost. The assembly extends in a straight line behind the output face.<\/div>\n<\/div>\n

\n
\u25c6 Right-Angle (90\u00b0)<\/div>\n
A hardened spiral-bevel gear pair<\/strong> is added at the input to redirect the motor axis by 90 degrees before the torque enters the planetary stages. The motor sits perpendicular to the output shaft, creating an L-shaped assembly.<\/p>\n

Result:<\/strong> Dramatically shorter depth behind the output face. The trade-off is the efficiency loss, additional backlash, noise, and weight contributed by the bevel input stage.<\/div>\n<\/div>\n<\/div>\n

\n
\n

The spiral-bevel gear pair in the right-angle configuration is the source of every performance trade-off discussed in this article. It adds approximately 3 arcmin of angular play (stacking with the planetary backlash), reduces efficiency by about 2% per stage, increases noise by 5\u201310 dB(A), and adds 15\u201330% to the unit weight compared to the equivalent inline model. These are fundamental physics consequences of adding an additional gear mesh \u2014 they apply to all right-angle planetary gearbox designs regardless of manufacturer.<\/p>\n

The critical question is not \u201cwhich configuration is better?\u201d but \u201cdoes the installation space constraint justify accepting these trade-offs?\u201d The answer depends entirely on the physical dimensions available in your machine frame.<\/p>\n<\/div>\n

\"Planetary<\/div>\n<\/div>\n

<\/p>\n

Installation Depth \u2014 The Primary Decision Driver<\/h2>\n

The reason engineers specify a right-angle planetary gearbox is almost always physical space. The chart below compares the axial depth (from output face to motor end-cap) of Korea Ever-Power inline versus right-angle models at each frame size, assuming a typical 400\u2013750 W servo motor.<\/p>\n

<\/p>\n

\n
AXIAL DEPTH COMPARISON \u2014 MOTOR + GEARBOX ASSEMBLY<\/div>\n
\n
\n
Frame 60<\/div>\n
\n
INLINE<\/div>\n
\n
~260 mm<\/span><\/div>\n<\/div>\n<\/div>\n
\n
RIGHT-ANGLE<\/div>\n
\n
~147 mm<\/span><\/div>\n<\/div>\n<\/div>\n
43% shorter<\/div>\n<\/div>\n
\n
Frame 80<\/div>\n
\n
INLINE<\/div>\n
\n
~320 mm<\/span><\/div>\n<\/div>\n<\/div>\n
\n
RIGHT-ANGLE<\/div>\n
\n
~172 mm<\/span><\/div>\n<\/div>\n<\/div>\n
46% shorter<\/div>\n<\/div>\n
\n
Frame 120<\/div>\n
\n
INLINE<\/div>\n
\n
~430 mm<\/span><\/div>\n<\/div>\n<\/div>\n
\n
RIGHT-ANGLE<\/div>\n
\n
~210 mm<\/span><\/div>\n<\/div>\n<\/div>\n
51% shorter<\/div>\n<\/div>\n<\/div>\n

Depth measured from output flange face to motor end-cap. Typical 400\u2013750 W servo motor. Values are approximate and depend on specific motor model.<\/p>\n<\/div>\n

The depth reduction is not marginal \u2014 it is transformative for machine design. A Frame 120 inline assembly extending 430 mm behind the output face may be impossible to fit in a conveyor frame, an AGV chassis, or a panel-mounted actuator housing. The right-angle variant at 210 mm solves the installation constraint entirely.<\/p>\n

\u2139 Design rule of thumb:<\/strong> If the available depth behind your driven axis is less than 70% of the inline motor-gearbox assembly length, the right-angle configuration is likely required. Measure the available envelope first \u2014 do not assume inline will fit just because the catalogue lists it.<\/div>\n

<\/p>\n

Efficiency and Precision \u2014 What the Bevel Stage Costs You<\/h2>\n

The spiral-bevel input stage in a right-angle unit is a precision-ground gear mesh that redirects the motor torque by 90 degrees. It is well-engineered and durable, but it is still an additional gear contact that was not present in the inline variant. Here is exactly what it costs across the key performance parameters:<\/p>\n

\n\n\n\n\n\n\n\n\n\n\n\n
Parameter<\/th>\n\uc778\ub77c\uc778<\/th>\n\uc9c1\uac01<\/th>\nDifference<\/th>\n<\/tr>\n<\/thead>\n
Efficiency (1-stage)<\/td>\n\u226596%<\/td>\n\u226594%<\/td>\n~2%<\/td>\n<\/tr>\n
Efficiency (2-stage)<\/td>\n\u226594%<\/td>\n\u226592%<\/td>\n~2%<\/td>\n<\/tr>\n
Backlash (standard, 1-stg)<\/td>\n\u22648 arcmin<\/td>\n\u226413\u201316 arcmin<\/td>\n+5\u20138 arcmin<\/td>\n<\/tr>\n
Backlash (precision, 1-stg)<\/td>\n\u22645 arcmin<\/td>\n\u22648 arcmin<\/td>\n+3 arcmin<\/td>\n<\/tr>\n
Noise (Frame 80)<\/td>\n\u226460 dB(A)<\/td>\n\u226473 dB(A)<\/td>\n+10\u201313 dB(A)<\/td>\n<\/tr>\n
Weight (Frame 80, 2-stg)<\/td>\n2.2 kg<\/td>\n5.0 kg<\/td>\n+127%<\/td>\n<\/tr>\n
Cost (same frame & ratio)<\/td>\nBaseline<\/td>\n+20\u201340%<\/td>\n\u2014<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

Data from Korea Ever-Power EP-PL\/PF (inline) vs EP-WPL\/WPF (right-angle) standard series. Precision series: EP-PBL\/PBF (inline) vs EP-WPBL\/WPBF (right-angle).<\/p>\n

\u26a0 Key insight:<\/strong> The backlash penalty is the most consequential trade-off. An inline unit at \u22648 arcmin becomes \u226413\u201316 arcmin in the right-angle configuration \u2014 potentially pushing the total backlash beyond the tolerance of precision positioning applications. If your application requires \u22648 arcmin and<\/strong> 90\u00b0 output, you must step up to the EP-WPBL\/WPBF precision right-angle series, which uses ground bevel gears to compress the bevel-stage backlash contribution.<\/div>\n

\"Korea<\/p>\n

<\/p>\n

When to Specify Inline<\/h2>\n

Choose the inline planetary gearbox as the default starting point<\/strong> for every new specification. Switch to right-angle only when a specific installation constraint forces it. Inline wins on every performance metric \u2014 efficiency, precision, cost, weight, and noise. The only parameter where the right-angle configuration has an advantage is installation depth. This means inline should be your default assumption during early machine design; only change to right-angle if the detailed layout drawing reveals an installation space conflict that cannot be resolved by repositioning the motor or adjusting the machine frame.<\/p>\n

\n
1<\/span><\/p>\n
CNC machine feed axes and rotary tables<\/strong>
\nBall-screw driven X\/Y\/Z axes have ample depth behind the drive end for an inline motor-gearbox assembly. The EP-PL\/PF inline planetary gearbox<\/a> at \u22648 arcmin or the EP-HAB at \u22643 arcmin delivers the tightest precision at the lowest cost for these applications.<\/span><\/div>\n<\/div>\n
2<\/span><\/p>\n
Packaging and pick-and-place machines<\/strong>
\nHigh-speed theta-axis drives and linear gantry axes benefit from the inline unit\u2019s lower weight and inertia. Reduced reflected inertia enables faster settle times and higher throughput. The efficiency advantage reduces heat generation, which is critical in enclosed machine frames.<\/span><\/div>\n<\/div>\n
3<\/span><\/p>\n
Semiconductor and laser processing equipment<\/strong>
\nWafer handling, beam steering, and precision dispensing demand the tightest backlash available. The inline EP-PBL\/PBF at \u22645 arcmin or EP-HAB at \u22643 arcmin is the natural choice. Switching to right-angle would add 3\u20138 arcmin of bevel-stage backlash that may push the total beyond the allowable positioning error budget.<\/span><\/div>\n<\/div>\n
4<\/span><\/p>\n
Energy-sensitive continuous-duty drives<\/strong>
\nEvery 2% of efficiency lost to the bevel stage translates into additional heat and wasted energy. In a 2 kW drive running 16 hours daily, the 2% difference amounts to approximately $47\/year per drive. For facilities with dozens of drives, inline selection across the board yields meaningful energy savings.<\/span><\/div>\n<\/div>\n<\/div>\n

<\/p>\n

When to Specify Right-Angle<\/h2>\n

The right-angle planetary gearbox is the correct choice only when the installation physically cannot accommodate the inline assembly length, or when the motor must be oriented perpendicular to the output for a specific engineering reason. In our experience working with machine builders across CNC, robotics, packaging, and AGV applications, approximately 30% of planetary gearbox installations genuinely require right-angle output \u2014 the remaining 70% are best served by inline. The four scenarios below represent the most common legitimate reasons for specifying a right-angle configuration.<\/p>\n

\"Right-angle<\/p>\n

\n
AGV \/ AMR wheel hub drives<\/strong><\/p>\n

The servo motor must sit at wheel-hub height within the vehicle chassis, not extending vertically above the wheel. The EP-WPL\/WPF right-angle planetary gearbox<\/a> routes the motor horizontally inside the chassis frame, keeping the centre of gravity low and the payload deck clear.<\/p>\n<\/div>\n

Wall-mounted or panel-flush conveyors<\/strong><\/p>\n

Packaging conveyors that run against walls or through machine frames leave no depth behind the drive roller. The right-angle unit mounts the motor parallel to the belt, within the available frame width. This is the most common application for the EP-WPF square-flange variant.<\/p>\n<\/div>\n

Vertical-axis drives with horizontal motors<\/strong><\/p>\n

Winding shafts, vertical indexing tables, and Z-axis lifters benefit from a horizontally mounted motor for easier cable routing and heat dissipation. The right-angle unit redirects the horizontal motor torque to a vertical output shaft without needing additional couplings or brackets.<\/p>\n<\/div>\n

Service access requires a side-mounted motor<\/strong><\/p>\n

In food processing and pharmaceutical lines where the operator side must remain clear, a right-angle configuration routes the motor away from the access zone. This also facilitates motor replacement during scheduled maintenance without disconnecting the gearbox from the driven load. Pair with a drive shaft<\/a> for articulating connections where needed.<\/p>\n<\/div>\n<\/div>\n

<\/p>\n

Noise and Vibration \u2014 How the Bevel Stage Affects Acoustics<\/h2>\n

The spiral-bevel input stage in a right-angle planetary gearbox introduces an additional gear mesh frequency that the inline variant does not produce. This manifests as a measurable increase in acoustic noise, particularly at higher input speeds. The comparison below uses Korea Ever-Power test data at 3,000 rpm input speed, measured at 1 metre distance.<\/p>\n

\n
\n
Inline Planetary Gearbox<\/div>\n
Frame 60: \u226458 dB(A)
\nFrame 80: \u226460 dB(A)
\nFrame 120: \u226465 dB(A)
\nSource:<\/strong> Planet gear mesh frequency only<\/div>\n<\/div>\n
\n
Right-Angle Planetary Gearbox<\/div>\n
Frame 60: \u226470 dB(A)
\nFrame 80: \u226473 dB(A)
\nFrame 120: \u226475 dB(A)
\nSource:<\/strong> Planet mesh + bevel mesh frequencies<\/div>\n<\/div>\n<\/div>\n

The 10\u201313 dB(A) increase may seem modest as a number, but in acoustics, a 10 dB increase represents a perceived doubling of loudness. In noise-sensitive environments such as cleanrooms, medical facilities, or operator workstations where the planetary gearbox runs within 2 metres of personnel, this difference can determine whether the installation meets workplace noise regulations. For these environments, the inline configuration should be the first choice whenever physically possible.<\/p>\n

\u2139 Noise reduction tip:<\/strong> If you must use a right-angle planetary gearbox in a noise-sensitive environment, specify a unit with helical-cut planet gears rather than spur-cut. Helical teeth maintain multiple teeth in simultaneous contact, spreading the acoustic energy across a wider frequency band and reducing the peak loudness of the dominant mesh frequency.<\/div>\n

<\/p>\n

Cost Comparison \u2014 Purchase Price and Lifetime Energy<\/h2>\n

The right-angle planetary gearbox costs more to purchase and more to operate than its inline equivalent. The dual cost penalty comes from two independent sources:<\/p>\n

\n
\n
<\/div>\n
Initial Purchase Premium<\/div>\n

A right-angle unit at the same frame and ratio costs 20\u201340%<\/strong> more than the inline equivalent. The premium covers the additional spiral-bevel gear pair (Gleason-type cutting + post-hardening grinding), its associated bearings, and the more complex housing machining. At the precision tier (EP-WPBL vs EP-PBL), the premium is at the higher end because the bevel gears require individual grinding and tooth-contact-pattern verification.<\/p>\n<\/div>\n

\n
<\/div>\n
Ongoing Energy Penalty<\/div>\n

The ~2% efficiency loss translates to ongoing energy waste. For a 1.5 kW drive running 8 hours daily at 250 days per year, the bevel stage wastes an additional 0.03 kW \u00d7 2,000 h = 60 kWh\/year<\/strong> (\u2248 $7\/year). For a single drive this is negligible, but across a facility with 50\u2013100 drives, the cumulative cost becomes meaningful. More importantly, the wasted energy becomes heat inside the gearbox, accelerating lubricant degradation and shortening bearing life.<\/p>\n<\/div>\n<\/div>\n

The cost conclusion is clear: if your installation accommodates inline mounting, you save on both the purchase price and the lifetime operating cost. Reserve the right-angle planetary gearbox premium for installations where the depth constraint genuinely demands it.<\/p>\n

Korea Ever-Power Series \u2014 Inline and Right-Angle Pairs<\/h2>\n

Each inline planetary gearbox series in the Korea Ever-Power portfolio has a direct right-angle counterpart that shares the same internal planetary gear train with an added spiral-bevel input stage. This consistent pairing simplifies specification: if you know which inline series meets your precision and protection grade requirement, the right-angle partner is the corresponding 90-degree variant with predictable performance trade-offs.<\/p>\n

\n\n\n\n\n\n\n\n
Tier<\/th>\nInline Series<\/th>\nRight-Angle Series<\/th>\nBacklash (1-stg)<\/th>\nIP<\/th>\n<\/tr>\n<\/thead>\n
Standard<\/td>\nEP-PL\/PF<\/td>\nEP-WPL\/WPF<\/td>\n\u22648\u2032 \u2192 \u226413\u201316\u2032<\/td>\n54<\/td>\n<\/tr>\n
Precision<\/td>\nEP-PBL\/PBF<\/td>\nEP-WPBL\/WPBF<\/td>\n\u22645\u2032 \u2192 \u22648\u2032<\/td>\n65<\/td>\n<\/tr>\n
Flagship<\/td>\nEP-HAB<\/td>\n(no RA variant)<\/td>\n\u22643\u2032<\/td>\n65<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

<\/p>\n

5-Point Decision Checklist<\/h2>\n
\n
\n
1<\/span> Is there sufficient axial depth for the inline assembly? \u2192 Yes = Inline<\/strong><\/div>\n
2<\/span> Is the motor blocked by a wall, structure, or clearance zone? \u2192 Yes = Right-Angle<\/strong><\/div>\n
3<\/span> Does the application need \u22648 arcmin backlash? \u2192 Prefer Inline (or precision RA)<\/strong><\/div>\n
4<\/span> Must the motor sit perpendicular for COG or service reasons? \u2192 Yes = Right-Angle<\/strong><\/div>\n
5<\/span> Is lowest cost and highest efficiency the priority? \u2192 Yes = Inline<\/strong><\/div>\n<\/div>\n<\/div>\n

\"Korea<\/p>\n

<\/p>\n

Frequently Asked Questions<\/h2>\n
\n
\n\u25b6 How much efficiency does the right-angle bevel stage lose?<\/summary>\n
Approximately 2% per reduction stage. A single-stage inline unit at \u226596% efficiency becomes \u226594% in the right-angle variant. At two stages, the inline achieves \u226594% while the right-angle achieves \u226592%. This 2% loss occurs in the spiral-bevel input mesh and is a fundamental characteristic of all right-angle designs, regardless of brand or price tier.<\/div>\n<\/details>\n
\n\u25b6 Why does the right-angle unit have wider backlash than inline?<\/summary>\n
The spiral-bevel gear pair adds approximately 3\u20138 arcmin of angular play that stacks with the planetary stage backlash. Even with precision-ground bevel gears and preloaded bearings, this bevel-stage contribution represents the physics floor for a 90-degree gear mesh. The EP-WPL\/WPF standard right-angle achieves \u226413\u201316 arcmin versus \u22648 arcmin for the inline EP-PL\/PF. The EP-WPBL\/WPBF precision right-angle compresses this to \u22648 arcmin by using ground bevel gears, but it still cannot match the inline EP-PBL\/PBF at \u22645 arcmin.<\/div>\n<\/details>\n
\n\u25b6 Can a right-angle unit be mounted in any orientation?<\/summary>\n
Yes. Korea Ever-Power right-angle units use grease lubrication that does not depend on an oil sump, so they can be mounted in any orientation \u2014 horizontal, vertical output-up, vertical output-down, or any angle in between. Ensure the motor cable exit direction does not create a strain loop in the installed position, and verify the servo drive can supply the motor at the chosen mounting angle without exceeding thermal limits.<\/div>\n<\/details>\n
\n\u25b6 Is the bevel gear in the right-angle unit a spiral-bevel or hypoid gear?<\/summary>\n
Korea Ever-Power uses spiral-bevel gears (intersecting axes), not hypoid gears (offset axes). Spiral-bevel gears maintain multiple teeth in contact for smooth load distribution and low noise, while avoiding the axial thrust loads that hypoid gears generate. This design choice provides the best balance of efficiency, noise, and manufacturing precision for servo planetary applications.<\/div>\n<\/details>\n
\n\u25b6 Is there a right-angle version of the EP-HAB flagship?<\/summary>\n
No. The EP-HAB is available only in inline configuration because its \u22643 arcmin backlash specification cannot be maintained with an additional bevel input stage. Adding a bevel gear pair would increase total backlash to approximately 6\u20138 arcmin, which would overlap with the EP-WPBL\/WPBF precision right-angle series and eliminate the flagship\u2019s performance differentiation. If you need both 90\u00b0 output and the tightest available backlash, the EP-WPBL\/WPBF at \u22648 arcmin is the closest option.<\/div>\n<\/details>\n
\n\u25b6 How much does a right-angle unit cost compared to the inline equivalent?<\/summary>\n
A right-angle unit typically costs 20\u201340% more than the inline equivalent at the same frame size and ratio, due to the additional spiral-bevel gear pair and its associated manufacturing costs (bevel cutting, grinding, tooth contact pattern verification). This cost premium is consistent across both standard and precision tiers. When installation space permits inline mounting, the cost saving is a direct benefit on top of the performance advantages.<\/div>\n<\/details>\n<\/div>\n

<\/p>\n

\n
Not Sure Whether Inline or Right-Angle Fits Your Machine?<\/div>\n

Send us your motor model, available installation depth, and required backlash tolerance. Our engineers will confirm the optimal configuration and series within one business day \u2014 no obligation.<\/p>\n

Get a Free Configuration Recommendation \u2192<\/a><\/p>\n<\/div>\n<\/div>\n

\ud3b8\uc9d1\uc790: Cxm<\/p>","protected":false},"excerpt":{"rendered":"

CONFIGURATION COMPARISON Inline vs Right-Angle Planetary Gearbox Same planetary gear train inside. Different motor orientation outside. That 90-degree bend costs you 2% efficiency and 5\u20138 arcmin of backlash \u2014 but it saves 40\u201350% of the installation depth behind the output face. Here is exactly when each trade-off is worth making. 40\u201350% DEPTH REDUCTION ~2% EFFICIENCY […]<\/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":[19],"tags":[],"class_list":["post-263","post","type-post","status-publish","format-standard","hentry","category-application-and-technical-guid"],"_links":{"self":[{"href":"https:\/\/planetary-gearboxes.cn\/ko\/wp-json\/wp\/v2\/posts\/263","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/planetary-gearboxes.cn\/ko\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/planetary-gearboxes.cn\/ko\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/planetary-gearboxes.cn\/ko\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/planetary-gearboxes.cn\/ko\/wp-json\/wp\/v2\/comments?post=263"}],"version-history":[{"count":2,"href":"https:\/\/planetary-gearboxes.cn\/ko\/wp-json\/wp\/v2\/posts\/263\/revisions"}],"predecessor-version":[{"id":265,"href":"https:\/\/planetary-gearboxes.cn\/ko\/wp-json\/wp\/v2\/posts\/263\/revisions\/265"}],"wp:attachment":[{"href":"https:\/\/planetary-gearboxes.cn\/ko\/wp-json\/wp\/v2\/media?parent=263"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/planetary-gearboxes.cn\/ko\/wp-json\/wp\/v2\/categories?post=263"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/planetary-gearboxes.cn\/ko\/wp-json\/wp\/v2\/tags?post=263"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}