Drives for metallurgy: gearboxes, motors, brakes and couplings
Metallurgical processing is one of the most demanding environments for drive equipment: shock loads on rolling mill stands, thermal shocks at converters and continuous casting machines (CCM), abrasive sinter dust, and frequent reversals on coilers and casting-shop cranes. Generic general-purpose solutions do not work here — purpose-built series rated for extended service life under peak torque are required, along with carefully matched motor-gearbox-coupling-brake assemblies.
Industry-typical tasks
- Main drives for blooming, plate and section rolling mills with torque up to 1.5 MN·m and starting overloads of 2.5–3×
- Drives for finishing stand groups and coilers (downcoiler, recoiler) with frequent reversals and precise speed control
- Roll and pinch-roll drives of continuous casting machines (CCM) — low speed, high torque, high ambient temperature
- Drives for sintering machines, rotary kilns, raw mix and coke crushers — continuous S1 duty with abrasive dust
- Conveyor drives for raw mix, ore, pellets and finished rolled stock — heavy starting and reversing under full load
- Casting-shop overhead cranes with ladles — dual braking systems, protection against dropping the molten load
- Drives for ID/FD fans of blast furnaces and sintering plants — MV motors rated 2–10 MW
- Hydraulic power units for hot-stamping presses, mill stand screw-down systems and CCM secondary cooling
Gearboxes
Metallurgical processes rely on three gearbox families: heavy-duty purpose-built units (main drives of rolling mills and CCMs), general-purpose industrial gearboxes (conveyors, elevators, ID fans), and planetary units with high ratios (low-speed kiln and mill drives). The key selection criterion is the design service factor (SF), which for rolling typically must be at least 1.8–2.5 to account for shock peaks, together with the permissible radial load on the output shaft when operating through a gear coupling.
Main drives for blooming and plate mills
Two- and three-stage parallel-shaft gearboxes with a double-helical (herringbone) output stage. Double-helical gears cancel axial loads and run more quietly than spur gears at high pitch-line velocities — critical in metallurgy given continuous duty and frequent starts. CGC ZSY/JST series with their patented dual power-split torsion-shaft design are well suited, rated up to 8,000 kW per housing.
- — Gear ratio 16–80
- — Output torque 200 kN·m – 1.5 MN·m
- — Service factor ≥ 2.0 (metallurgy), ≥ 2.5 (hot rolling)
- — Forced circulating lubrication with oil cooler
- — Shock-load compensation on the output shaft
Coiler and recoiler gearboxes
A high reversal frequency (up to 200 cycles per hour) and precise tension-torque control demand special gearboxes with low rotor inertia and bearings with increased radial clearance. Downcoilers use coaxial planetary stages or helical-planetary combinations.
- — Low output-shaft inertia
- — Heavy-duty bearings sized for the coil radial load
- — Compatibility with speed control via incremental encoder
- — Seals protected against mill scale ingress
CCM roll drives
Low-speed gearmotors with a compact footprint for the tight space of the casting strand. They operate within the radiant heat field of the strand and require heat-resistant seals, synthetic oil with a high viscosity index, and additional water cooling of the housing. The CGC ESP series covers the complete gearbox set for endless strip production lines.
- — Radiant-heat protection for seals and shafts
- — Synthetic oil VG 220–320
- — IP56 or higher with protection against water spray (secondary cooling)
- — Redundant lubrication system (main / standby pump)
Drives for rotary kilns and sintering furnaces
Two- to four-stage parallel-shaft or bevel-helical gearboxes with high ratios. Mounted on the girth gear of the kiln support shell. Continuous duty (S1, 24/7), low output speed (1–4 rpm), and a high radial load from the kiln weight. Two identical gearboxes are often paired on a single girth gear for torque sharing.
- — Gear ratio 200–500
- — Capability for paired operation with torque sharing
- — Oil pump station with filtration and cooling
- — Bearing vibration and temperature monitoring
Conveyor drives for raw mix and rolled stock
General-purpose bevel-helical (K series) or parallel-shaft (F series) gearmotors. Heavy starting under load requires SF ≥ 1.5 and a thermal-duty check — long metallurgical conveyors often run in a "start every 3–4 minutes" pattern, closer to S4 than to S1. Hold-back systems require provisions for a backstop or an electromagnetic brake.
- — K series (15°/45° bevel) or F series (parallel-shaft)
- — Service factor of at least 1.5
- — Option to fit a brake or backstop
- — Gearbox protection on belt jam (shear pin / slip sensor)
High-power electric motors
Main drives for rolling mills, mills, ID fans and FD/ID draft machines in metallurgy are the domain of MV induction and synchronous motors rated from 800 kW to 15 MW at 6, 10 or 11 kV. The motor must meet specific requirements: speed control via an MV variable-frequency drive, high starting torque, bearing protection against shaft-current breakdown, and thermal margin for sustained overloads.
Main drives for reversing rolling mill stands
Synchronous motors or induction motors with an MV inverter operating in four-quadrant mode. The duty cycle includes up to 6 reversals per minute with peak torque of 2.5–3× rated. The Wolong YHTM series for wind power and metallurgy delivers up to 12 MW with rated-load efficiency above 98%.
- — Rating 5–12 MW, voltage 6/10 kV
- — Insulated bearing on the non-drive end (to mitigate shaft currents)
- — Forced cooling IC81W (water-to-air)
- — Pt100 RTDs on windings and bearings
Drives for continuous mills and coilers
Predominantly induction motors with an MV drive and speed/torque feedback. They require the fastest possible torque response (10–20 ms) and precise torque holding for strip-tension control. Wolong WD3000 motors with forced water cooling and 1.8× rated starting torque are well matched here.
- — Inverter-duty rating (class H insulation, NEMA MG1 Part 31)
- — Encoder with at least 4,096 ppr
- — Thermal margin for S4 duty — 60 cycles per hour
- — Ingress protection IP55 minimum
Motors for ID and FD fans
Continuous S1 duty, rating 800–4,000 kW, 6 kV, speed 750–1,000 rpm. Flow control is via inlet vanes or a variable-frequency drive; the latter saves up to 30% energy and is preferred for new installations. The motor operates with vibration transmitted from the fan, so a reinforced foundation and real-time vibration monitoring are required.
- — Class F insulation with class B thermal reserve
- — Vibration monitoring per ISO 10816-3 (zone B)
- — Capability to start via soft-starter or inverter
- — IP55 with additional dust protection for the ambient air
Drives for crushers and mills
Heavy starting under load (resistive torque 1.5–2× rated) with frequent stops for discharge. Induction motors with rotor-resistance starting or a fluid coupling between the motor and gearbox are used — this limits inrush current on the grid. For slag mills, the typical solution is "motor + Jiaohua fluid coupling + CGC gearbox".
- — Starting torque ≥ 1.8× rated
- — Fluid-coupling compatibility (flange + register ring)
- — Thermal protection for frequent starts (S4–S6)
- — Heavy-duty bearings for the radial load from pulley/coupling
Industrial brakes
Metallurgical plant safety depends directly on the braking systems. A casting-shop crane carrying a 350-tonne ladle of molten metal must have two independent brake systems (service and emergency), each rated to hold the full load. Beyond hoisting, brakes are installed on inclined conveyors, coilers, hot shear drives, and in emergency stop systems for rolling mill stands.
Brakes for ladle and charging cranes
Electrohydraulic disc brakes of the Huawu YPZ2/YWZ5 series are mounted on the hoist drum. A two-brake scheme is used: a service (primary) brake plus a redundant emergency brake of the spring-applied fail-safe type. Engagement on power loss occurs within 0.1–0.2 s. For molten-metal ladles, certification per GOST 31303 (metallurgical cranes) is mandatory.
- — Braking torque with 1.75–2.0× safety margin over the rated hoist torque
- — Response time on power loss ≤ 0.2 s
- — Ingress protection IP55, ambient temperature up to +60 °C
- — Dual brake set (service + emergency)
Brakes for inclined conveyors and sintering machine drives
TKT/TKK shoe brakes with an electrohydraulic thruster hold the conveyor on shutdown and prevent uncontrolled reverse run under the load weight. Hot sintering machines use heat-resistant variants with ceramic linings and cooling-air blast.
- — Heat-resistant shoes (up to +200 °C at the brake drum)
- — Electrohydraulic thruster Ed-50 to Ed-301
- — Manual release option for maintenance
- — Lining wear monitoring (limit switch)
Emergency brakes for rolling stands and shears
Stands with high inertia (coilers, hot shears) are fitted with a hydraulically clamped emergency disc brake. When protection trips, the main motor is de-energised and the brake closes within 0.15–0.3 s, stopping the stand before the motor coasts down — critical to prevent roll damage on a strip jam.
- — Hydraulic clamp with spring-applied engagement
- — Response time 0.15–0.3 s
- — Electronic monitoring of position and pressure
- — Compatibility with the rolling mill PLC system
Storm brakes for gantry cranes at steel yards
Open-yard portal and gantry cranes use rail-clamp storm brakes — Jingu CWZ or Zhonghai SB. They hold the crane on the rails under wind gusts up to 35 m/s during off-duty hours. Engagement is automatic above a preset wind speed or on power loss.
- — Holding capacity up to 35 m/s wind
- — Automatic engagement on anemometer signal
- — Redundant power supply (UPS)
- — CE certification and pneumatic release
Couplings
Four coupling types are used in metallurgical drives: drum gear couplings on rolling mill main drives (high torque plus misalignment compensation), pin-and-bushing flexible couplings on conveyors and pumps (damping), fluid couplings on crushers and mills (soft start and motor overload protection), and rolling mill spindles — a dedicated class with cardan joints. Couplings are selected for torque with a 1.5–2× safety margin and for permissible shaft misalignment once the equipment has reached operating temperature.
Gear couplings for rolling mill main drives
Yongjing GIICL / Longxuan WGZ drum-type double-engagement gear couplings transmit torque up to 1.5 MN·m while compensating radial, axial and angular shaft misalignment. Crowned tooth profiles allow operation at angular misalignment up to 1.5°. Grease lubrication is applied via a grease nipple with a 6-month service interval.
- — Torque 200 kN·m – 1.5 MN·m
- — Angular misalignment compensation up to 1.5°
- — Compatibility with the stand spindle coupling
- — G6.3 balancing at peripheral speeds > 15 m/s
Pin-and-bushing flexible couplings for conveyor drives
Jiaohua YOXp/YOXz and Yongjing LX (LMC) series — pin couplings with elastic bushings. They damp shock loads at start-up and compensate minor misalignment. On conveyor drives they are typically combined with a brake drum (coupling-with-drum design), saving space and simplifying service.
- — Torque 5–125 kN·m
- — Radial misalignment compensation 0.2–1.0 mm
- — Integrable with a brake drum
- — Elastic-element service life of at least 30,000 h
Fluid couplings for crushers and mills
Jiaohua YOX/COX fluid couplings with oil filling provide soft starting under heavy load (slag mills, raw mix crushers). Rated slip of 2–3% protects the motor from overload if the driven rotor jams. Variants with a fusible safety plug discharge oil overboard on overheating and shut the drive down automatically.
- — Rated slip 2–4%
- — Fusible plug set point 145–160 °C
- — Oil fill 70–85% of internal volume
- — Thermal margin for 4–6 starts per hour
Cardan spindles for rolling mill stands
Yongjing SWP/SWC and Longxuan universal cardan shafts transmit torque from the gearbox to the work stand under significant axial and angular misalignment (up to 5–10° per joint). They are used between the main gearbox and the roll stands of blooming, finishing and section mills. Hot rolling applications require heat-resistant seals and cooling.
- — Torque 50–800 kN·m
- — Permissible joint misalignment up to 10°
- — Forged-steel crosses with rolling-element bearings
- — Pre-installation balancing per GOST 22061-76
Applications gallery
Our solutions for this industry
SDS portfolio brands that cover typical applications in this industry.
- CGCheavy-duty gearboxes for rolling mills and CCMs — ZSY, JST, ESP and Coiler series. 60% market share for cement and metallurgical gearboxes in China
- WOLONGMV main-drive motors (YHTM, WD3000) rated up to 12 MW; general-purpose YE/YBX3 motors for auxiliary drives
- HUAWUbraking systems for ladle and charging cranes (YPZ2, YWZ5) and Ed-series electrohydraulic thrusters
- JINGUrail-clamp storm brakes for gantry cranes at steel yards, plus disc and shoe brakes
- ZHONGHAIexplosion-proof and storm brakes for special-duty applications in metallurgical plants
- YONGJINGGIICL drum gear couplings for main drives and SWC/SWP cardan spindles for rolling mill stands
- JIAOHUAYOX/COX fluid couplings for crushers and slag mills, plus permanent-magnet couplings for energy-efficient drives
- LONGXUANWGZ gear couplings, LX flexible pin couplings and brake drums for conveyor and hoist drives
- BONENGK, F and HB industrial gearmotors for raw-mix conveyors, belt conveyors and auxiliary unit drives
- DONLYhydraulic power units for hot-stamping presses, mill stand screw-down systems and CCM secondary cooling
- DEODFL/DFLA oil coolers for main-drive gearboxes and plate heat exchangers for lubrication systems
- ANNENGtrolley busbar systems for ladle and charging cranes in casting-shop environments
Image credits: Wikimedia Commons (Public domain) · DDEKK (CC0) · Wikimedia Commons (Public domain) · Martin Stupich (Public domain) · Petteri Aimonen (Public domain)