Slewing Drive Series Planetary Gearbox
Trusted Across Industries:
Tower Crane Slewing
Mobile & Crawler Crane
Utility Boom & Digger Derrick
Drilling Rig Rotary
Port & Harbor Crane
Wind Turbine Yaw & Pitch
Mining & Construction
Why Choose Our Slewing Drive Planetary Gearbox? — Our Slewing Drive Series is specifically engineered for pinion-output slewing applications — the most demanding duty cycle in construction and industrial machinery. Featuring case-hardened alloy steel planetary gear sets, heavy-capacity output shaft bearings sized for combined radial and moment loads, an integral precision-ground output pinion shaft, and a fully enclosed housing with static and dynamic braking options, our swing drive gearbox delivers reliable 360° slewing performance in the harshest excavator, crane, and industrial environments — with full custom planetary slewing drive solutions available for OEM machine builders.
Product Overview — Slewing Drive Series Planetary Gearbox
The Slewing Drive Series Planetary Gearbox — also known as a swing drive gearbox, slewing reduction gearbox, planetary slewing drive, or slew drive reducer — is a specialised planetary gearbox in which the output is not a shaft, flange, or rotating housing, but an integral precision-ground pinion gear shaft. This pinion meshes directly with the large-diameter slewing ring gear (turntable gear / swing bearing gear) fixed to the machine's undercarriage or base structure, causing the upper structure of the machine — excavator cab and boom, crane superstructure, drilling rig rotary table — to rotate through a full 360° under controlled hydraulic or electric motor power.
In excavators, the swing drive gearbox sits at the exact centre of the machine, physically dividing the rotating upper structure from the stationary undercarriage. The hydraulic swing motor drives the planetary gearbox input, the planetary reduction multiplies torque and reduces speed, and the output pinion rotates inside the stationary ring gear — swinging the entire excavator house. Without the swing drive, an excavator's cab, boom, and arm would be locked in a fixed direction relative to the tracks — requiring the machine to physically reposition itself for every change in working direction, eliminating the excavator's fundamental productivity advantage.
Our Slewing Drive Series covers output torque from 1,000 N·m to 180,000 N·m, gear ratios from 4.96:1 to over 200:1, single and double-reduction planetary stages, SAE A through SAE D hydraulic motor flanges, and a comprehensive custom engineering capability for non-standard applications. As a specialist slewing drive planetary gearbox manufacturer, we supply replacement swing drive gearboxes for all major excavator and crane brands, as well as bespoke slewing drive solutions for new machine designs.
Technical Specifications — Slewing Drive Series Planetary Gearbox
The table below covers the standard Slewing Drive Series specification range. All units are factory-assembled, lubricated, and tested under full load before shipment. Custom pinion modules, tooth counts, motor flange configurations, and mounting arrangements are available — contact our engineering team with your specific requirements.
| Parameter | Specification / Range | Notes |
|---|---|---|
| Transmission Type | Single / Double Reduction Planetary | Coaxial; pinion output shaft |
| Output Torque Range | 1,000 N·m – 180,000 N·m | Full series coverage; match model to required torque |
| Gear Ratio Range | Single: 3.92:1 – 52.35:1 / Double: up to 200+:1 | Custom ratios available on request |
| Max Input Speed | 3,500 RPM (single) / 5,000 RPM (double) | Typical hydraulic orbit and axial-piston motor speeds |
| Transmission Efficiency | 96% – 98% | Per stage; planetary advantage over worm drives |
| Output Interface | Integral Precision-Ground Output Pinion Shaft | Splines to DIN 5480 or custom; meshes with slewing ring gear |
| Pinion Configuration | External Straight, Helical, or Custom Pinion | Module, tooth count, and PCD to match OEM slewing ring |
| Eccentric Mounting Option | Eccentric Casing Available | For precise pinion-to-ring gear backlash adjustment in field |
| Motor Flange Standard | SAE A, SAE B, SAE C, SAE D | Per SAE J744; all common hydraulic swing motor sizes |
| Braking System | Static Brake (standard) / Static + Dynamic Brake | All swing drives require at minimum static parking brake |
| Brake Release | Spring-Applied / Hydraulic or Electric Release | SAHR fail-safe design standard |
| Output Shaft Bearings | Heavy-Capacity Self-Aligning Roller Bearings | Sized for radial and moment loads from pinion-ring gear mesh |
| Housing Material | High-Strength Ductile Iron GGG-50 / Cast Steel | Withstands shock loads and vibration in construction duty |
| Gear Material | 18CrNiMo7-6 / 20CrMnTi Alloy Steel | Carburized, 58-62 HRC, profile-ground DIN/ISO Class 6 |
| Sealing / IP Protection | IP65 standard / IP67 heavy-duty option | Fully enclosed; dust and water-jet resistant |
| Lubrication | Mineral or Synthetic Gear Oil per SAE J306 | Initial change at 50–100 hours; intervals per duty cycle |
| Operating Temperature | -30°C to +100°C | Extended low-temp and high-temp options available |
| Surface Treatment | Epoxy primer + two-component PU topcoat | Salt spray above 500 hours per ISO 9227 |
| Design Life (B10) | 3,000+ hours at rated load | Per FEM/ISO crane and construction machinery standards |
| Certification | ISO 9001:2015, CE; DNV/BV/ABS available for marine | Factory acceptance test report with every unit |
| Custom Engineering | Full OEM Custom Design Capability | Pinion module, ratio, mounting, braking — all configurable |
| Lead Time | 15 – 45 days (standard) / 45 – 90 days (custom) | Common excavator replacement models in stock |
Need a custom pinion module, non-standard gear ratio, or a custom planetary slewing drive solution for a new machine design? Submit your application parameters to our engineering team — we confirm feasibility and provide a preliminary specification within 48 hours.
Slewing Drive Series — Torque Range & Application Guide
Select the correct model class based on your required continuous output torque at the pinion shaft. All models are available with static brake (standard) or static plus dynamic brake (for applications requiring deceleration control). Contact our engineers with your machine make, model, and operating weight for a direct recommendation.
| Model Class | Continuous Torque | Ratio Range | Typical Application |
|---|---|---|---|
| SD-10 | 1,000 – 3,000 N·m | 3.75 – 33.79:1 | Light utility crane, aerial lift, digger derrick boom rotation |
| SD-20 | 3,000 – 6,000 N·m | 3.92 – 52.35:1 | Mini excavator (1–3 T), compact crane, truck-mounted crane |
| SD-40 | 6,000 – 12,000 N·m | 4.96 – 52.35:1 | Midi excavator (3–8 T), mobile crane, logger/grapple carrier |
| SD-60 | 12,000 – 25,000 N·m | 5.50 – 52.35:1 | Medium excavator (8–20 T), tower crane, pile driver |
| SD-100 | 25,000 – 50,000 N·m | 20.52 – 52.35:1 | Large excavator (20–50 T), crawler crane, port crane |
| SD-150 | 50,000 – 100,000 N·m | 20.52 – 46.00:1 | Heavy excavator (50–100 T), heavy crawler crane, offshore crane |
| SD-200+ | 100,000 – 180,000 N·m | Custom | Mining excavator (100+ T), shipyard crane, offshore platform |
How the Slewing Drive Planetary Gearbox Works
The slewing drive planetary gearbox converts high-speed, low-torque hydraulic motor output into slow, powerful rotation of the machine's upper structure through the engagement of an integral output pinion with the large-diameter slewing ring gear. Unlike wheel drives or shaft-output drives, every component is optimised for the unique dynamic demands of slewing: shock loading on swing reversals, eccentric radial and moment loads from the pinion mesh force, and the need for precision position control through the hydraulic circuit.
Hydraulic Motor Input
An SAE-flanged hydraulic axial-piston or orbit motor drives the planetary sun gear at high speed. The operator controls motor flow direction (forward/reverse) and speed through the joystick-operated hydraulic directional control valve, giving precise slewing speed and direction control from the cab.
Planetary Gear Reduction
The sun gear drives three or more planet gears orbiting in the fixed ring gear. The planet carrier rotates at reduced speed with multiplied torque — typically one or two planetary stages providing 5:1 to 52:1 reduction within the gearbox before the output pinion stage further reduces speed in the slewing ring mesh.
Output Pinion Shaft
The final planet carrier drives the integral output pinion shaft, which extends from the bottom of the gearbox housing. This precision-ground pinion gear meshes directly with the large-diameter slewing ring gear (turntable bearing gear ring) fixed to the machine's undercarriage or base structure.
Slewing Ring Engagement
The pinion walks around the inside of the stationary slewing ring gear, carrying the gearbox, motor, and the entire upper structure of the machine with it. This final gear reduction — the ratio of the slewing ring pitch diameter to the pinion pitch diameter — provides the overall system slew speed and the total system output torque at the slewing ring.
Braking System
A spring-applied, hydraulically released parking brake on the input stage locks the entire drive train — and therefore the upper structure — when hydraulic pressure is released. This prevents uncontrolled drift on slopes and serves as the transport lock. A dynamic brake (counter-pressure or friction disc) controls deceleration on swing reversals in demanding crane duty cycles.
Core Advantages — Slewing Drive Planetary Gearbox
Eight engineering and commercial advantages that make our slewing drive planetary gearbox the preferred choice for excavator and crane OEMs, aftermarket replacement procurement teams, and custom machine builders worldwide.
Full Torque Range Coverage: 1,000 – 180,000 N·m
A single product series covers the complete slewing drive application range — from light utility cranes and aerial lifts at 1,000 N·m through to 100+ tonne mining excavators and offshore cranes at 180,000 N·m. One supplier, one contact, one quality system across all machine sizes.
Replacement Swing Drive for Excavator — All Major Brands
We stock or manufacture direct-fit replacement swing drive gearboxes for excavators from Komatsu, Hitachi, Caterpillar, Volvo, Doosan, Hyundai, Liebherr, and other major OEMs. Provide your excavator make, model, and serial number — we confirm the correct unit within 24 hours.
Custom Planetary Slewing Drive Solutions
As a full-capability slewing drive planetary gearbox manufacturer, we design and manufacture custom planetary slewing drive solutions for new machine programs — custom pinion modules, non-standard gear ratios, eccentric mounting configurations, dual-motor inputs, and custom braking specifications. Engineering review within 48 hours.
96–98% Efficiency vs Worm Drive Alternatives
Planetary gear architecture achieves 96–98% transmission efficiency — compared to 40–70% for worm gear slewing drives. This means significantly less power wasted as heat, lower hydraulic system temperature, reduced fuel consumption, and longer hydraulic component life across the entire machine duty cycle.
Heavy-Duty Braking — Static and Dynamic
All swing drives require at minimum a static parking brake for transport safety. We supply both static-only and combined static plus dynamic braking configurations. Dynamic braking controls deceleration forces on swing reversals — critical for crane duty cycles where load inertia creates significant impact forces if unchecked.
Eccentric Mounting for Precise Backlash Adjustment
Available with eccentric casing mounting — the pinion axis is offset from the housing axis by an adjustable eccentric amount — allowing precise field adjustment of the pinion-to-ring gear backlash. This is critical for tower cranes and precision slewing applications where backlash directly affects positioning accuracy and reverse-motion jerk.
Heavy-Capacity Pinion Shaft Bearing System
The output pinion shaft experiences the full radial mesh force from the slewing ring engagement plus the structural bending moment from pinion offset — the highest-stress bearing location in the machine. Our heavy-capacity self-aligning roller bearings are generously sized per FEM calculation standards to provide long bearing life under worst-case combined loading.
Marine & Offshore Class Certification Available
For marine crane, offshore platform, and ship-mounted slewing drive applications, we can supply units with classification society approval from DNV GL, Bureau Veritas (BV), American Bureau of Shipping (ABS), and Lloyd's Register — with dedicated marine corrosion-resistant sealing, coatings, and documentation packages.
Structure Design and Material Engineering
The Slewing Drive Series is engineered to survive the harshest duty cycles in construction and industrial machinery — high-cycle swing reversals, sustained heavy loads, outdoor exposure, particulate contamination, and extreme temperature variation. Every component is selected and sized for the unique mechanical demands of the pinion-output slewing drive configuration.
Output Pinion Shaft
Alloy steel, vacuum carburized, case-hardened to 58-62 HRC, profile-ground to DIN/ISO Class 6. The pinion is precision-ground to the specified module and tooth profile for accurate mesh with the OEM slewing ring gear. Splined to DIN 5480 or custom specification. Bearing seating diameters ground to h6 tolerance.
Pinion Shaft Bearing System
Generously dimensioned self-aligning roller bearing pairs support the output pinion shaft in a rigid housing section designed to minimise deflection under maximum mesh load. Bearing sizing is performed per FEM Section I methodology with B10 life calculation at the application duty cycle. Bearing nut provides precise preload and positive retention.
Planetary Gear Set
18CrNiMo7-6 or 20CrMnTi alloy steel sun, planet, and ring gears, vacuum carburized, 58-62 HRC, precision-ground to DIN/ISO Class 6. Planet carrier from alloy steel forging — not cast iron. Ring gear positively locked to housing to prevent rotation under shock loading and swing reversal impact.
Housing and Casing
High-strength ductile iron GGG-50 or cast steel housing provides the rigidity needed to maintain pinion bearing alignment under maximum slewing mesh loads. Optional eccentric casing allows ± backlash adjustment in field without shim changes. Mounting flange holes per machine OEM specification.
Braking System
Spring-applied, hydraulically released multi-disc brake on the input stage, enclosed within the housing. Springs engage at zero hydraulic pressure — fail-safe. Dynamic braking option uses a friction disc or counter-pressure valve arrangement for deceleration control. Brake torque calculation provided per application duty cycle on request.
Sealing and Environmental Protection
Fully enclosed housing with HNBR lip seals at all shaft exits. IP65 standard — dust-tight and water-jet resistant. IP67 option for submerged or high-pressure wash applications. Marine stainless steel fasteners and epoxy coating available for offshore and coastal environments.
Motor Mounting Interface
SAE A, B, C, or D motor flange per SAE J744, CNC-machined to tolerance. Compatible with all major hydraulic swing motor brands. Splined input per SAE J744 or DIN 5480. For electric motor applications, IEC B5 adaptor plates are available for AC, servo, or permanent-magnet motors.
Surface Treatment
Epoxy zinc phosphate primer (80 µm) plus two-component PU topcoat (80 µm), salt spray above 500 hours per ISO 9227. RAL colour matching available for OEM machine colour coding. Marine-grade epoxy coating option for 1,000+ hour salt spray resistance for offshore and port crane applications.
Typical Application Scenarios
The Slewing Drive Series Planetary Gearbox is deployed across six core heavy machinery and industrial application categories where controlled 360° rotation under maximum torque is required in demanding outdoor environments.
Excavator Swing Drive
The swing drive sits at the centre of the excavator, physically connecting rotating upper structure to stationary undercarriage. The hydraulic swing motor drives the planetary gearbox, and the output pinion walks inside the stationary slewing ring gear — rotating the cab, boom, stick, and bucket through a full 360°. This rotation capability is what fundamentally separates an excavator from any other digging machine. Our replacement swing drive for excavator applications covers all machine weight classes from 1-tonne mini excavators to 100+ tonne mining excavators.
Tower Crane Slewing Drive
Tower cranes use the slewing drive gearbox to rotate the jib (horizontal boom) and hook block around the mast, enabling materials to be picked up and placed at any point within the crane's radius. Tower crane applications demand precise backlash control (eccentric casing option), accurate positioning for load placement, and reliable dynamic braking to prevent uncontrolled jib oscillation under load momentum. We supply slewing drives for Liebherr, Potain, Terex, and other major tower crane platforms.
Mobile and Crawler Crane
Mobile and crawler cranes use one or more slewing drive gearboxes to rotate the superstructure (boom, counterweight, cab) relative to the carrier. The high torque capacity of the planetary slewing drive allows rapid, smooth slewing with suspended loads, while the static brake prevents superstructure drift on sloped ground and during transport. We supply custom slewing drive solutions for mobile crane manufacturers including Liebherr, Manitowoc/Grove, Terex, Tadano, and Sany.
Utility Boom & Digger Derrick
Truck-mounted aerial work platforms, digger derricks, and utility line service vehicles use slewing drive gearboxes to rotate the boom about a vertical axis on the truck chassis. These applications require compact, lightweight units — our SD-10 and SD-20 classes — with reliable static brake for safe personnel positioning at height. Both hydraulic and electric motor configurations are available for hybrid and electric utility truck platforms.
Port, Harbor & Shipyard Crane
Ship-to-shore cranes, harbour mobile cranes, and shipyard portal cranes use large-capacity slewing drive gearboxes for superstructure rotation during cargo handling operations. Marine duty cycles demand high-cycle endurance, marine-grade sealing and coating, and classification society approval. We supply slewing drives with DNV GL, BV, ABS, and Lloyd's Register certification for marine and offshore crane applications.
Industrial Slewing & Wind Turbine
Wind turbine yaw drives, turbine blade pitch drives, radar antenna positioning systems, drilling rig rotary tables, and industrial positioners all use planetary slewing drives for their combination of high torque, compact size, and precise positioning. Our custom planetary slewing drive solutions capability covers non-standard ratios, dual-redundant motor inputs, feedback encoder integration, and environmental specifications for wind, offshore, and defence applications.
OEM Replacement Cross-Reference — Swing Drive Gearbox
Our Slewing Drive Series Planetary Gearbox is cross-referenced to the following OEM swing drive and slewing drive products. We verify pinion module, tooth count, motor flange standard, and housing mounting interface before confirming replacement compatibility. OEM names referenced for cross-compatibility purposes only.
| OEM Brand | Compatible Series / Platform | Torque Range | Typical Machine |
|---|---|---|---|
| Komatsu | PC88 / PC130 / PC200 / PC300 / PC400 Swing Drive | 3,000–50,000 N·m | Mini to large hydraulic excavator |
| Hitachi | ZX50 / ZX120 / ZX200 / ZX330 / ZX450 Swing | 3,000–60,000 N·m | Mini to heavy excavator |
| Caterpillar | 303 / 308 / 320 / 336 / 390 Swing Drive | 2,000–60,000 N·m | Mini to large excavator |
| Volvo | EC55 / EC140 / EC210 / EC360 / EC460 Swing | 3,000–55,000 N·m | Compact to heavy excavator |
| Doosan / HD Hyundai | DX85 / DX140 / DX225 / DX380 Swing Drive | 3,000–50,000 N·m | Compact to large excavator |
| Auburn Gear (SW Series) | Model 6 SW / Larger SW Swing Drive Series | 2,800–19,800 N·m | Construction, utility, aerial lift |
| Liebherr | R900 / R918 / R936 / R945 Slewing Drive | 5,000–80,000 N·m | Medium to heavy excavator, crane |
| Zollern | Slewing Gear Series (tower crane, ship crane) | 5,000–180,000 N·m | Tower crane, harbor crane, offshore |
Don't see your excavator or crane model listed? Provide your machine make, model, serial number, and if possible the existing swing drive part number — our team confirms the correct replacement unit within 24 hours. Submit Your Cross-Reference Request
Related Products — Compatible Drive Components
Compatible Motors for the Slewing Drive Series
The Slewing Drive Series is engineered for direct hydraulic and electric motor attachment — all SAE A through D flanges and IEC B5 motor interfaces are available as standard factory options. Our matched motor range covers the complete input power and speed envelope of the slewing drive series, from hydraulic axial-piston swing motors for excavators, cranes, and utility booms, to electric servo and AC motors for wind turbine yaw drives, industrial positioners, and electric-drive crane applications — all factory-paired and fully loaded-tested as a complete drive assembly before shipment.
Hydraulic Axial-Piston Swing Motors
SAE B / C / D flange — displacement 55 to 500 cc/rev, continuous pressure 350–450 bar. The standard motor type for the Slewing Drive Series in excavator, crawler crane, mobile crane, and port crane applications. Direct SAE flange mount — no adaptor required for the most common swing motor configurations from major hydraulic brands.
Hydraulic Orbit Motors
SAE A / B / C flange — compact and cost-effective for utility boom, digger derrick, aerial work platform, and light crane slewing applications in the SD-10 and SD-20 torque classes. Direct SAE flange mount to standard slewing drive input interfaces with no adaptor plate required.
IEC Electric Motors (B5)
IEC B5 adaptor flanges are available for AC induction, permanent-magnet servo, and variable-frequency drive motors — for wind turbine yaw drives, industrial positioners, electric crane applications, and hybrid electric utility machines requiring precise slewing speed and position control without a hydraulic circuit.
Frequently Asked Questions
Common questions from excavator fleet managers, crane OEM engineers, and aftermarket procurement teams about our slewing drive planetary gearbox and replacement swing drive services.
Quality Assurance and Standards Compliance
Manufactured under ISO 9001:2015 with full material and process traceability. Key quality milestones specific to the slewing drive application include:
- Incoming Material: Spectroscopic alloy analysis on all gear steel, housing castings, and pinion forging. Hardness verification per batch. Dimensional check of all blanks before machining.
- Pinion Gear Accuracy: Output pinion profile and lead measured on gear measurement machine to DIN/ISO Class 6 or better. Tooth surface roughness Ra measured. Hardness case depth verified by destructive sampling per batch.
- Planetary Gear Set: 100% CMM profile and lead on planet and sun gears. Ring gear statistical sampling. Planet carrier from alloy steel forging verified by material certificate.
- Pinion Shaft Bearing Housing: Bore diameter and roundness measured to confirm correct bearing interference fit. Bearing installation torque recorded per unit.
- Brake Testing: Every brake pack tested at 125% rated holding torque before assembly. Release pressure and minimum release pressure verified and recorded.
- Factory Acceptance Test: Full-load run-in at rated torque and speed, efficiency measurement, oil seal air-pressure leak test, and oil temperature monitoring. Full test report issued per unit. Archives retained 10 years.
How to Select or Order the Correct Slewing Drive
Whether you need a stock replacement for a known excavator model or a custom slewing drive specification, follow these steps — or simply provide your machine details and we handle the rest.
Step 1: Define Torque Requirement
For replacement: note the existing gearbox nameplate torque or provide machine make/model/serial. For new design: calculate required output torque at the pinion shaft = (machine inertia × angular acceleration) + (load moment × friction factor). Apply service factor 1.5–2.5 for construction duty.
Step 2: Confirm Pinion Specification
For replacement: record the pinion module, number of teeth, and pressure angle from the existing gearbox or machine drawing. For new design: the pinion module and tooth count must match the slewing ring gear already specified or being designed.
Step 3: Specify Motor Interface
Confirm hydraulic motor type and SAE flange designation (A, B, C, or D). For electric drive, confirm IEC motor frame and power. Provide motor model number or displacement for confirmation of input speed and torque at rated hydraulic circuit conditions.
Step 4: Confirm Braking
Specify static brake only (for excavator and utility boom applications) or static plus dynamic brake (for crane applications). For dynamic braking, provide maximum swing speed and load inertia for brake torque calculation. Specify hydraulic or electric brake release.
Step 5: Confirm Mounting & Options
Confirm housing mounting flange pattern, eccentric casing requirement, environmental protection level, and any certification requirements (marine class, ATEX, etc.). State quantity for stock check and volume pricing. Custom and OEM volume programs: contact our engineering team directly.
Free Application Engineering Review: Send your machine make and model (for replacement) or your torque, speed, pinion, and braking requirements (for new designs). Our engineers will specify the correct slewing drive model, perform a preliminary bearing life calculation, and provide a dimensional outline within 48 hours — completely free.
Source Your Slewing Drive Planetary Gearbox Today
Whether you need an urgent replacement swing drive for excavator to minimise costly machine downtime, require custom planetary slewing drive solutions for a new OEM machine program, or are sourcing production volumes as a leading slewing drive planetary gearbox manufacturer partner — our team delivers the right unit, the right specification, and the right support backed by 20 or more years of planetary gearbox manufacturing expertise for the construction and crane industries.
Explore our complete planetary gearbox range at planetary-gearboxes.net, or speak directly with a slewing drive specialist via our Contact Us page.
