Drives for port equipment: gearboxes, motors, brakes and couplings
A seaport is an environment where drive equipment operates at the intersection of three aggressive factors: salt fog and 100% humidity accelerate corrosion of bearings and windings; gusts up to 35 m/s create the risk of cranes being driven uncontrolled along the rails; and 24/7 cargo handling leaves no window for extended maintenance. An STS quay crane lifts a 65-ton container every 90 seconds, an RTG repositions a stack block without halting the shift, and a ship loader feeds coal at 6,000 t/h — general-purpose series simply do not survive here. The application calls for marine-grade drives with corrosion-resistant coatings, storm-protection rail clamps with anemometer-driven automation, and crane VFDs with regenerative braking energy recovery.
Industry-typical tasks
- Main hoist of STS quay cranes — payload up to 65 t with spreader, lift height 30–50 m, speed 60–90 m/min when running empty
- Trolley travel of the STS crane and gantry travel of RTG/RMG cranes — precise positioning, long start-and-brake cycles
- Boom and slewing drives of ship loaders and ship unloaders — compensation of vessel motion, boom conveyor lines rated 1,500–6,000 t/h
- Luffing and hoisting drives of level-luffing portal cranes — constant hook height across an outreach range of 10–35 m
- Quay conveyor systems for bulk cargo handling (grain, coal, iron ore concentrate, fertilizers) — long belts, heavy starts under full load
- Reach stackers and port stackers — hydraulic boom-extension drives and diesel-electric travel drives
- Mooring and tug winches at the berth — sustained torque holding under cable tension
- Storm protection of cranes during downtime — rail clamps and storm brakes with automatic actuation triggered by the anemometer
Gearboxes
Port drivetrains rely on three gearbox families: heavy crane-duty series for the main hoist and gantry travel of quay cranes; industrial gear-motors for trolleys and auxiliary mechanisms; and dedicated conveyor units for bulk-handling systems. The decisive criterion is marine-grade execution: a C5-M anti-corrosion housing coating per ISO 12944, stainless fasteners and breathers, and synthetic oil with anti-emulsification protection in case of seawater ingress. The service factor for port cranes is no less than 1.6, and 2.0 for the STS main hoist to account for shock loads during container handover.
Main hoist of STS quay cranes
Heavy two- and three-stage parallel-shaft gearboxes with a double-helical (herringbone) output stage. Output torque 250–600 kN·m at drive ratings of 800–1,500 kW. CGC ZSY/JST series with split-power transmission are a good fit — they reduce overall envelope at the same rated power and ensure even load sharing between gear meshes. Marine-coated housing, forced circulation lubrication, separate-foundation air-to-oil cooler.
- — Gear ratio 20–63
- — Output torque 250–600 kN·m
- — Service factor ≥ 2.0
- — Anti-corrosion coating C5-M (ISO 12944)
- — Forced lubrication with 10 µm filtration
- — Bearing temperature monitoring via Pt100
Gantry and trolley travel drives
Boneng helical-bevel K-series or parallel-shaft F-series gear-motors — compact mounting on the bogie without a remote motor. Each STS crane wheel has a dedicated gear-motor to prevent rail slip under wind loading. Precise trolley positioning requires VFD operation with an encoder and a gearbox with low output-shaft backlash.
- — K-series (90° helical-bevel) or F-series (parallel-shaft)
- — Gear ratio 25–125
- — Output-shaft backlash ≤ 6 arc-minutes
- — Provision for a shaft-end encoder
- — Marine-grade IP66 execution
- — Reinforced bearings for radial loads
Boom and slewing drives of ship loaders
The slewing platforms of ship loaders and grab unloaders are equipped with planetary gearboxes of high reduction ratio. The luffing drive combines a parallel-shaft gearbox with a brake drum and a compensating hydraulic cylinder. Continuous S1 duty at bulk-handling rates of 1,500–6,000 t/h requires thermal verification of the housing and forced oil cooling.
- — Gear ratio 100–315
- — Output torque up to 1 MN·m (platform slewing)
- — Service factor ≥ 1.8
- — Oil cooler with a closed seawater loop
- — Redundant lubrication system
Conveyor drives for quay systems
General-purpose gear-motors for conveyors handling grain, coal and ore. Long conveyors (300–1,200 m) carry several drive stations per belt with even torque distribution. A heavy start under full load requires SF ≥ 1.5 and a thermal check. On inclined sections a backstop is mandatory to prevent the belt from running backwards on power loss.
- — K-series or R-series (in-line)
- — Service factor ≥ 1.5
- — Backstop mounting option
- — Dust and water ingress protection IP66
- — Twin-drive operation with torque balancing
RTG and RMG terminal crane drives
Rubber-tyred RTGs and rail-mounted RMGs at container terminals are equipped with gear-motors on every gantry wheel and on the trolley. Gantry travel requires precise synchronous control of all wheel drives through closed-loop VFDs — otherwise the gantry skews on uneven pavement. The Boneng HB series is designed for continuous duty in container-terminal conditions.
- — Individual drive on each wheel
- — Synchronization via CAN or PROFIBUS
- — Marine-grade C5-M execution
- — Inverter-duty compatibility
- — PTC thermal protection in the winding
Electric motors and variable frequency drives
Main drives of STS quay cranes and ship loaders are induction motors rated 200–1,500 kW at low and medium voltage (380, 660, 1,000 V) with forced cooling and mandatory marine-grade winding insulation. All main port drives run through crane-duty VFDs with regenerative braking energy recovery, returning the container-lowering energy back to the grid — this cuts terminal power consumption by 20–30% and eliminates heat dissipation in braking resistors. The motors face specific demands: reinforced class H insulation for frequent starts, thermal reserve for S4–S6 duty, and bearing protection against induced shaft currents on inverter supply.
STS main hoist motors
Induction motors rated 600–1,500 kW with forced water or air cooling IC81W. The container-handling duty cycle calls for up to 35 working cycles per hour with a starting torque of 1.8 times rated. Wolong WD3000 motors are a good fit, with a 4,096 ppr encoder and thermal reserve for S4 duty. The winding is impregnated with moisture-resistant varnish, with mandatory Pt100 RTDs in every phase and in both bearing shields.
- — Rating 600–1,500 kW, voltage 660/1,000 V
- — Insulation class H, NEMA MG1 Part 31 (inverter-duty)
- — Encoder resolution ≥ 4,096 ppr
- — Insulated bearing on the coupling end
- — Forced cooling, IP55
- — Thermal reserve for S4 — 40 cycles per hour
Travel and trolley motors
Induction motors rated 30–110 kW with a brake integrated into the rear shield. Used on every gantry wheel and on the trolley winch. Marine-grade execution is mandatory — the motors are exposed outdoors to direct salt fog. Wolong YE3/YBX3 series are offered in IP66 with stainless fasteners.
- — Ingress protection IP66, marine-grade
- — Integrated DC brake
- — Anti-corrosion housing coating
- — PTC thermal protection in the winding
- — Inverter-duty compatibility
Crane-duty variable frequency drives
Regenerative VFDs with an active front end (AFE) for main hoist and travel duty. They return up to 95% of the container-lowering energy to the grid, which matters economically — over a shift, every second lowering carries a loaded container and every second a returning empty spreader, and in both cases the braking energy can be reused. INVT GD350-Crane and Inovance MD500-Crane series carry certified software modules for STS, RTG and ship-loader applications with ready-made control macros.
- — AFE regenerative module (energy returned to the grid)
- — Certified crane macros (STS, RTG, ship loader)
- — Four-quadrant control
- — Encoder compatibility
- — Mains dip ride-through 200 ms
Quay-area conveyor motors
Continuous S1 duty at 75–315 kW. The motors operate amid bulk-handling dust and salty humidity. IP66 execution with additional bearing-housing protection against dust ingress. Inclined conveyors require either a brake motor or an external electromagnetic brake to prevent reverse motion.
- — IP66 with additional bearing protection
- — Continuous S1 duty at 100% load
- — Anti-corrosion coating
- — Soft-starter or inverter starting capability
- — Insulation class F with class B temperature rise
Brake systems and storm protection
Braking safety on a port crane consists of two independent systems. The first is the service brakes on the main-hoist and trolley winch drums driven by electrohydraulic thrusters. The second is storm protection: rail clamps that hold the crane on its rails under gusts up to 35 m/s during downtime. Without the second system the port cannot be commissioned — this is mandated by port-facility safety rules and FEM standards. Main-hoist winches additionally carry spring-applied emergency brakes that engage on power loss within 0.15–0.2 s.
STS main-hoist disc brakes
Huawu YPZ2/YWZ5 series electrohydraulic disc brakes on the main-hoist winch drum. A dual-brake arrangement is used: a service brake (released by oil pressure, applied by springs) and an emergency brake with an independent hydraulic power unit. On power loss both brakes engage automatically within 0.15 s, holding the container at any point of the lift. Marine-grade execution with anti-corrosion coating and stainless cylinder rods.
- — Braking torque margin 1.75–2.0 over rated
- — Engagement time on power loss ≤ 0.2 s
- — Dual-brake arrangement (service + emergency)
- — Marine-grade execution, salt-fog protection
- — Pad wear monitoring
JINGU CWZ storm rail clamps
CWZ rail clamps are mounted on the gantry of STS cranes and RTG/RMG units. They engage automatically on the anemometer signal when wind speed exceeds the setpoint (typically 20 m/s — out-of-service mode; 28 m/s — mandatory clamping). On mains power loss the clamps engage from a dedicated UPS. They hold the crane under gusts up to 35 m/s with a 1.5 safety factor. It is a port-critical system — without it the crane can be driven down the rails by a gust and destroyed.
- — Hold-down rated for winds up to 35 m/s
- — Anemometer-triggered actuation (20/28 m/s setpoints)
- — UPS backup for 4 hours
- — FEM/CE certification
- — Marine-grade, stainless steel
- — Pneumatic release for maintenance
ZHONGHAI SB marine-grade storm brakes
SB shoe-type storm brakes with increased clamping force and ceramic linings. Used on ship loaders, grab unloaders and portal cranes at open berths. Fully sealed enclosure with salt-corrosion protection and zinc-coated fasteners. Engagement time 0.5–1.5 s, sufficient for storm protection during downtime.
- — Hold-down force rated for winds up to 35 m/s
- — Shoes with ceramic linings
- — Zinc-coated fasteners, Zn 12 µm
- — IP66, marine-grade
- — Compatibility with port control systems
Brakes for inclined quay conveyors
TKT/TKK shoe brakes with an electrohydraulic thruster for inclined coal, grain and fertilizer conveyors. They hold the belt on shutdown and prevent reverse motion under load weight. On long conveyors a combined arrangement is used: a main brake on the low-speed shaft and a backstop on the high-speed shaft for additional protection.
- — Electrohydraulic thruster Ed-50–Ed-301
- — Marine-grade shoes and springs
- — Manual release option
- — Pad wear monitoring
- — Compatibility with a shaft-mounted backstop
Couplings, current collectors and cable systems
Beyond classical couplings, port drives require dedicated components for transmitting power and signals to moving parts — the STS trolley, the RMG bridge, the slewing platforms of ship loaders. These include trolley busways for long berths and main-hoist cable reels that wind the trolley supply cable across 50–80 m of travel. Without them the very concept of a container terminal would not work. The couplings in a port drivetrain include gear drum couplings on main hoist drives, elastic pin-and-bush couplings on conveyors, fluid couplings on long bulk-handling conveyors, and combined brake-drum couplings on small- and medium-rated winches.
Gear couplings for STS main hoist and ship loaders
Yongjing GIICL / Longxuan WGZ double-engagement gear couplings transmit torque from the motor through the gearbox to the winch drum. The crowned tooth profile accommodates angular misalignment up to 1°, which matters for the long drum spans of an STS hoist. Marine-grade execution with protection against grease wash-out by salt moisture — labyrinth seals and heavy grease with a 6-month service interval.
- — Torque 100–600 kN·m
- — Angular misalignment up to 1°
- — Marine-grade execution, stainless fasteners
- — Labyrinth seals
- — Balancing grade G6.3
LONGXUAN brake-drum couplings on winches
Combined couplings with an integrated brake drum for travel, slewing and auxiliary winch drives. They save space in the confined geometry of the crane structure and simplify service — the brake and coupling are removed as one assembly. Torque 5–125 kN·m, polyurethane pin-and-bush elements damp shock loads on start-up.
- — Torque 5–125 kN·m
- — Integrated brake drum
- — Polyurethane elastic elements
- — Marine-grade execution
- — Elastic-element service life ≥ 30,000 h
JIAOHUA fluid couplings for quay conveyors
YOX/COX fluid couplings provide a soft start for long quay conveyors under full coal or grain load. Rated slip of 2–3% protects the motor against overload if the belt jams. A fusible plug rated 145–160 °C dumps the oil on overheat and automatically shuts down the drive. On multi-drive conveyors fluid couplings also balance torque distribution between drives.
- — Rated slip 2–4%
- — Fusible plug rated 145–160 °C
- — Marine-grade housing
- — Thermal reserve for 4–6 starts per hour
- — Optional safety valve
ANNENG trolley busways and cable reels
Power to the STS trolley and the RMG bridge is supplied through trolley busways along the span or through a motor-driven cable reel. The main-hoist cable reel winds 80–120 m of 4 × 95 mm² power cable, maintaining constant tension through a spring or electric drive. Contact trolleys carry currents up to 1,000 A as the trolley travels. The Anneng series is designed specifically for port conditions — IP66, marine-grade, salt-corrosion-protected.
- — Cable-reel power capacity up to 1,500 kW
- — Winding length 50–120 m
- — Power-cable cross-section up to 4 × 120 mm²
- — Marine-grade IP66
- — Compatibility with the trolley VFD control system
TIANIU backstops for quay conveyors
NJZ/NB backstop couplings are installed on the low-speed shaft of an inclined-conveyor drive station. They prevent reverse belt motion on drive shutdown — without them a 600 m conveyor with 800 t of coal in transit would run back and tear out the take-up. Marine-grade execution with seals against salt fog.
- — Holding torque 50–500 kN·m
- — Mounted on the low-speed shaft
- — Marine-grade execution with labyrinth seals
- — Self-lubricating design
- — Compatibility with the conveyor brake
Applications gallery
Our solutions for this industry
SDS portfolio brands that cover typical applications in this industry.
- CGCheavy-duty gearboxes for the main hoist of STS quay cranes and the slewing platforms of ship loaders — ZSY and JST series in marine-grade C5-M execution
- BONENGgear-motors for gantry travel, trolley travel and RTG/RMG wheel drives — K, F and HB series in IP66 execution for port conditions
- WOLONGhigh-voltage main-hoist motors (WD3000) and general-purpose YE3/YBX3 in marine-grade execution for trolleys and auxiliary drives
- HUAWUYPZ2/YWZ5 electrohydraulic disc brakes for main-hoist winch drums and spring-applied emergency brakes
- JINGUCWZ rail clamps — a port-critical storm-protection system for STS quay cranes and RMG gantries, holding under winds up to 35 m/s
- ZHONGHAISB marine-grade storm shoe brakes for ship loaders and grab unloaders at open berths
- YONGJINGGIICL gear drum couplings for main hoist and slewing drives, plus cardan spindles for travel drives
- LONGXUANcombined brake-drum couplings for travel and slewing winches, and pin-and-bush flexible couplings for conveyor drives
- JIAOHUAYOX/COX fluid couplings for long quay conveyors handling coal, grain and ore — soft start and overload protection
- ANNENGtrolley busways and main-hoist cable reels — port-critical power-supply components for STS trolleys and RMG bridges, marine-grade IP66
- INVTGD350-Crane crane-duty VFDs with regenerative recovery of container-lowering energy — up to 30% terminal power savings
- INOVANCEMD500-Crane crane-duty VFDs with certified macros for STS, RTG and ship loaders, plus synchronization of gantry-wheel drives
- TIANIUNJZ/NB backstops for inclined quay conveyors — protection against reverse belt motion on drive shutdown
- JUDEgeneral-purpose flexible couplings for auxiliary crane drives and quay-area conveyor systems
Image credits: Syced (CC0) · ROBINSON NIÑAL/PPD (Public domain) · Alf van Beem (CC0) · Chad Hargrave, CSIRO (CC BY 3.0) · Bernard Spragg. NZ (CC0)