Drives for drilling equipment: exploration, open-pit, tunneling and underground
Drilling equipment in mining and underground operations works under some of the harshest duty conditions: impact loads on rotary blasthole bits in hard rock, sustained reverse rotation of exploration core drilling rods, peak torques on the main drive of a TBM stalled in a collapsed face, abrasive dust and cuttings, and the methane explosion hazard of underground mines. General-purpose industrial drives do not survive here — the application calls for purpose-built gearboxes rated for shock service factors, large high-voltage motors, brakes with guaranteed holding, hydraulic power units rated for 25–35 MPa working pressure and couplings with overload protection.
Industry-typical tasks
- Spindle drive of an exploration core drilling rig in the 22–160 kW range with rod torque up to 12 kN·m
- Main drive of a rotary blasthole drill rig for open-pit blast hole drilling (75–450 kW, bit diameter 200–311 mm)
- Main drive of a TBM (tunnel boring machine) cutterhead at 1,500–5,000 kW with peak torque up to 25 MN·m
- Cutter head drive of an underground roadheader (200–600 kW) with stall protection in hard rock
- Hydraulic power units for drill rigs and rotary blasthole rigs at 25–35 MPa working pressure with variable-displacement pumps
- Drawworks and rod-feed drives with a dual braking system and an overrunning clutch on descent
- Geotechnical and civil engineering drilling for piled foundations and ground anchors — kelly bar rotary heads with torque 250–600 kN·m
- Underground jumbo drills and bolters in gassy mines (methane category) — Ex-rated drives and brakes
Gearboxes
Drilling equipment uses three families of gearboxes: rotary drives for rods and spindles of drilling rigs (high-torque, low-inertia gear motors), main planetary gearboxes for TBMs (ratios of 200–500 and torques up to 25 MN·m) and roadheader cutter-head gearboxes with integrated stall protection. The service factor for hard-rock drilling must be at least 2.0 to account for impact loads when the bit encounters hard inclusions, and seals must withstand drilling fluid, abrasive cuttings and water ingress.
Spindle drive of an exploration core drilling rig
Two- and three-stage bevel-helical or planetary gear motors mounted on the spindle of the rotary head. They transmit torque to the drill string when boring with a diamond bit through category V–XII rock. They require reinforced output-shaft bearings to handle the axial load from the weight of the drill string (up to 5–15 metric tons) and reversing duty when unscrewing rods.
- — Gear ratio 16–63
- — Output torque 3–12 kN·m
- — Service factor ≥ 1.8 for category XI–XII rock
- — Full-load reversing capability
- — Seals resistant to drilling fluid (bentonite, polymers)
Main planetary drive of a TBM
Multi-stage planetary gearboxes weighing 30–120 metric tons, installed between a bank of HV motors and the cutterhead of the TBM. The drive consists of 6–12 identical motor + planetary gearbox modules running in parallel through the large bull gear of the cutterhead. The ratio is 200–500 and the output speed is 1–5 rpm. Forced circulating lubrication is used with an oil cooler and metal-particle monitoring in the oil.
- — Gear ratio 200–500
- — Module output torque 1–4 MN·m (combined up to 25 MN·m)
- — Forced lubrication with 10 µm filtration
- — Magnetic plugs and iron-content sensors in the oil
- — Synchronous operation of 6–12 gearboxes on a single bull gear
Roadheader cutter head drive
Two- to three-stage parallel-shaft or planetary gearboxes in the boom section of an underground roadheader. They run with continuous pick contact at the face, with shock loads of 1.5–2.2× rated torque. The gearbox housing carries the bending load from the weight of the cutter head and the reaction torque — it is structurally reinforced and is often integral with the boom.
- — Output torque 50–200 kN·m
- — Service factor ≥ 2.2 (shock duty in coal/rock)
- — IP67 with protection against the water spray used for dust suppression
- — Operation at ±25° tilt
- — Bearing and oil temperature monitoring
Kelly bar rotary head drive (piling)
Two- to four-stage planetary rotary head gearboxes for piling and ground-anchor rigs. They transmit rotary torque to a telescopic kelly bar when drilling soils and weak rocks for bored piles of 600–2,500 mm diameter. They require high output torque at low speed (15–35 rpm) and a compact envelope for mast mounting.
- — Output torque 250–600 kN·m
- — Output speed 15–35 rpm
- — Compact axial envelope for mast mounting
- — Hollow output shaft for the kelly bar
- — Protection against soil and water ingress (IP66)
Drawworks and rod-feed drive
Parallel-shaft or bevel-helical gearboxes for the tripping winch on rotary blasthole and core drilling rigs. They are combined with a brake and an overrunning clutch for controlled descent under the self-weight of the drill string. They are also used in hydraulic rod pulldown drives with torque up to 80 kN·m.
- — Output torque 20–80 kN·m
- — Overrunning clutch or brake on the input shaft
- — S2-30 min duty when raising the drill string
- — Compatibility with a multi-disc band or disc brake
- — Oil sight glass and dust-protected breather
Large electric motors
Three classes of motors are used in drilling equipment: general-purpose industrial asynchronous motors for exploration and civil engineering rigs (22–250 kW, 380/660 V), high-voltage motors for the main drive of TBMs (1,500–5,000 kW, 6/10 kV) and explosion-proof motors for underground mines in the methane category (Ex db I Mb / Ex db IIB T4). Open-pit rotary blasthole rigs use motors with forced ventilation and reinforced insulation rated for dust and ambient swings.
Main drive of a TBM cutterhead
A bank of 6–12 high-voltage asynchronous motors of 250–500 kW each, running in parallel on the common bull gear of the gearbox. They are fed from an HV variable-frequency drive that provides torque synchronization between modules and a soft start when the cutterhead is stalled in a face collapse. The Wolong YHTM/WD series for tunneling and metallurgy delivers up to 630 kW per module at 6/10 kV.
- — Module rating 250–630 kW, 6/10 kV
- — Class H insulation, inverter-duty compliant (NEMA MG1 Part 31)
- — Forced cooling IC616 (air-air) or IC81W (water-air)
- — Pt100 sensors on windings and bearings, insulated non-drive bearing
- — Vibration protection per ISO 10816-3
Main drive of an open-pit rotary blasthole drill rig
Asynchronous motors of 75–450 kW driving the rotary head and the compressor of the blasthole drill rig. They run in continuous S1 duty with frequent restarts when the rig is repositioned. Large rigs of the D245S/SKS class use 6 kV HV motors started through a soft starter; smaller rigs use LV motors with DOL starting or VFD control.
- — Rating 75–450 kW
- — IP55 protection, outdoor execution
- — Reinforced insulation against dust and ambient swings of −30 to +50 °C
- — Anti-condensation winding heaters at standstill
- — Starting torque ≥ 1.8× rated
Roadheader cutter drive
Explosion-proof Ex db I Mb motors of 200–600 kW for gassy underground coal and ore mines. The housing is cast steel with flameproof flame-path protection. Water cooling through a jacket on the housing keeps the outer surface temperature below 150 °C even on overload, which is critical for methane safety.
- — Marking Ex db I Mb (coal mines) or Ex db IIB T4
- — Rating 200–600 kW
- — Water cooling through a housing jacket
- — Outer surface temperature ≤ 150 °C on overload
- — Certification per TR CU 012/2011 or IECEx
Core and geotechnical drilling rig drive
General-purpose Wolong YE3/YBX3 asynchronous motors of 22–160 kW for XJ-300/XJ-1000 exploration rigs and civil engineering piling rigs. They typically run through a torque converter or fluid coupling to soften shock loads and to protect the motor when the bit jams. Protection class IP55, ruggedized for transport loads on self-propelled rigs.
- — Rating 22–160 kW, 380/660 V
- — Insulation class F with class B temperature rise margin
- — IP55 with anti-vibration execution
- — Compatibility with a fluid coupling / VFD
- — Anti-condensation heaters for service in wet conditions
Industrial brakes
Brake systems in drilling equipment serve two purposes: controlled descent of the drill string under self-weight (the service brake of the drawworks) and emergency stopping of rod rotation or the cutter head if it jams. Inclined drilling machines add a backstop that prevents the string from running back when the drive fails. Underground mines in explosive atmospheres call for Ex-rated executions with surface temperature protection and non-sparking cermet linings.
Drawworks brakes
Huawu YPZ2/YWZ electrohydraulic disc brakes are installed on the drawworks drum for controlled descent of the rod string and the bit. A dual-brake scheme is used: a service brake (running, speed-controlling) plus an emergency brake (spring-applied, fail-safe). It engages within 0.15–0.25 s on loss of power or a protection signal.
- — Braking torque with a 1.75 margin over the rated string-hoisting torque
- — Response time on power-off ≤ 0.25 s
- — IP55 protection, ambient temperature −20 to +50 °C
- — Dual brake set (service + emergency)
- — Lining wear monitoring
Backstops for inclined drilling machines
Tianiu NJZ-series backstops are installed on the high-speed shaft of the feed gearbox or on the drawworks of an inclined rig. They allow free rotation in the drilling direction and lock instantly on attempted reverse rotation under the weight of the string. They are sized to hold the full pulling force without slipping and have a defined service life by number of engagements.
- — Holding torque of 1.5× rated pulling torque
- — Allowable engagements — at least 100,000 cycles
- — Oil-lubricated execution compatible with gearbox oil
- — Maintenance-free life of at least 30,000 h
- — Compatibility with standard IEC/NEMA flanges
Ex-rated brakes for roadheaders and drill jumbos
Zhonghai explosion-proof brakes rated Ex db I Mb for gassy underground coal and ore mines. They are installed on the travel drive and on the cutter drive of roadheaders and jumbo drills. They are spring-applied on power loss and released by an electromagnet or a hydraulic cylinder. The design excludes sparking and surface heating above 150 °C on actuation.
- — Marking Ex db I Mb (coal mines) or Ex db IIB T4
- — Braking torque 0.5–25 kN·m
- — Spring-applied, electromagnetic or hydraulic release
- — Non-sparking cermet linings
- — Surface temperature on actuation ≤ 150 °C
Parking brakes for TBMs and shield machines
Hydraulic spring-applied disc brakes on the main drive of a TBM cutterhead. They hold the cutterhead in position at standstill for cutter changes or maintenance. They include hydraulic-cylinder pressure monitoring and an electronic interlock that prevents accidental release while the drive is running.
- — Holding the full cutterhead torque with a 1.5 margin
- — Hydraulic clamping with spring-applied actuation
- — Pressure and pad-position monitoring (sensors)
- — Compatibility with the TBM PLC system and the start interlock
- — Manual emergency release for maintenance
Couplings and hydraulics
Drilling equipment uses rigid flanged couplings on the main drive of TBMs, flexible pin-bushing couplings on exploration rigs, fluid couplings for heavy starts of rotary blasthole rigs and roadheaders, and gear-type drum couplings on large drives. A separate class is hydraulic systems and power units that generate the rod feed force, the bit pulldown, the rotary head drive and mast lifting. Hydraulics for drilling equipment is a flagship area of the DONLY range: power units rated for 25–35 MPa working pressure are engineered to project specifications with variable-displacement axial-piston pumps and 10 µm filtration.
Hydraulic power units for drill rigs
DONLY power units with Hengli variable-displacement axial-piston pumps (Rexroth-compatible) rated for 25–35 MPa working pressure. They are engineered to project specifications for a specific rotary blasthole or core drilling rig and integrate five to eight circuits — rotary head, rod feed, mast lifting, jacks, drawworks, dust-suppression hammer. The reservoir is 400–2,500 L with a heat exchanger and 10 µm filtration on the suction and return lines.
- — Working pressure 25–35 MPa
- — Variable-displacement Hengli axial-piston pumps with power control
- — Reservoir 400–2,500 L with a heat exchanger and 10 µm filtration
- — Huade/INI directional valves with proportional control
- — Oil cleanliness per ISO 4406 of at least 18/16/13
Heavy-start fluid couplings
Jiaohua YOX/YOXII fluid couplings between the motor and the main-drive gearbox of a rotary blasthole rig or roadheader cutter. They provide a soft start under full load and protect the motor from overload when the bit or cutter jams in hard rock. Rated slip is 2–4 %; a fusible plug set to 145–160 °C dumps oil to the outside on overheating.
- — Rated slip 2–4 %
- — Fusible plug set to 145–160 °C
- — Oil fill 70–85 % of internal volume
- — Thermal margin for 4–6 starts per hour
- — Compatibility with motors of 75–600 kW
Hydraulic components for drilling rotary heads
Hengli axial-piston hydraulic motors and Huade/INI proportional valves on the hydraulic rotary heads of drilling rigs. They are used on piling rigs and bolters, where a hydraulic rotary head drive is preferred over an electromechanical one for its compactness and smooth torque control. Manifold blocks are engineered to project specifications with make-up restrictors, check valves and 35 MPa relief valves.
- — Hydraulic motors 32–500 cm³/rev rated for up to 35 MPa
- — Huade DBE/DBET proportional valves
- — Check and relief valves rated for 35 MPa
- — Custom-engineered manifolds per project
- — Compatibility with the rig PLC (CAN/Profibus)
Rigid and flexible couplings for drilling equipment
Yongjing LX / Longxuan pin-bushing flexible couplings on the rotary head shafts of exploration rigs, plus flanged couplings with elastomer inserts between the motor and the feed gearbox. Inclined rigs add Yongjing SWC cardan shafts where shaft offset is significant. Couplings are sized with a torque margin of 1.5–2× rated to account for drilling impact loads.
- — Torque 1–80 kN·m
- — Misalignment compensation up to 1 mm radial and 0.5° angular
- — Torque margin of 1.5–2× the calculated value
- — Compatibility with a brake drum (combined executions)
- — Service life of elastomer elements of at least 25,000 h
Applications gallery
Our solutions for this industry
SDS portfolio brands that cover typical applications in this industry.
- BONENGGear motors for the rotary drives of exploration and civil engineering drilling rigs; K/HB series for rod feed and kelly-bar rotary heads
- WOLONGHigh-voltage motors for TBM main drives (YHTM, WD3000) at 250–630 kW per module; general-purpose YE3/YBX3 motors at 22–450 kW for rotary blasthole and core drilling rigs
- DONLYProject-engineered hydraulic power units for drill rigs and rotary blasthole rigs rated for 25–35 MPa working pressure — a flagship area of the range
- HUAWUYPZ2/YWZ electrohydraulic disc brakes for drawworks and drill-string tripping systems
- HUADEDBE/DBET proportional directional valves, plus relief and check valves rated for 35 MPa for drilling equipment hydraulic power units
- INIHydraulic components and manifold blocks for the hydraulic rotary heads of piling rigs and ground-anchor bolters
- HENGLIAxial-piston pumps and hydraulic motors for power units and rotary heads of drilling rigs, rated for up to 35 MPa
- YONGJINGLX pin-bushing flexible couplings and SWC cardan shafts for rotary head shafts and inclined drilling machines
- LONGXUANWGZ gear couplings and pin-bushing flexible couplings for drawworks and rotary blasthole rig drives
- JIAOHUAYOX/YOXII fluid couplings for heavy starts of open-pit rotary blasthole rigs and roadheaders
- TIANIUNJZ backstops for inclined drilling machines and drawworks
- ZHONGHAIEx db I Mb explosion-proof brakes for underground roadheaders and jumbo drills in gassy mines
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