Mine machinery and haulage

Mining Engineering (B.E./B.Tech) · Mine operations · free study notes for exams, placements and interviews

In short

Mine machinery and haulage covers the equipment that loads broken rock and transports it from the face to the surface, plus the men and materials moved with it. In Indian coal mines the chain runs face machine (SDL, LHD, continuous miner, shovel) → intermediate transport (shuttle car, dumper, chain conveyor) → main transport (belt conveyor, rope haulage, locomotive, winding) → surface. It is the costliest part of mine operating expense and the single largest source of fatal accidents after roof fall, which is why DGMS regulates almost every item. It is examined in GATE Mining (machinery, haulage calculations, winding), university Mine Machinery / Mine Transport papers and in interviews at Coal India subsidiaries, SCCL, NMDC, Tata Steel, Vedanta, Hindustan Zinc, Adani and the mining-equipment OEMs (BEML, Caterpillar, Komatsu, Sandvik, Epiroc, Liebherr).

Explained

Loading and face machinery

SDL (Side Discharge Loader): crawler-mounted gathering-arm loader of about 1.5–2.5 t capacity; it scoops coal onto its own conveyor and discharges sideways into a tub or chain conveyor. Cheap, needs 2.4 m width, poor output (150–300 t/day).
LHD (Load Haul Dumper): articulated, rubber-tyred, four-wheel-drive bucket loader of 1–6 m³ that loads, carries 50–200 m and dumps; the workhorse of Indian bord-and-pillar mines and of metal mines (shrinkage, sub-level stoping).
Continuous miner (CM): a drum with picks cuts coal and loads it in one operation through gathering arms onto a chain conveyor, feeding a shuttle car or flexible conveyor train. Indian CM panels (first at SCCL's GDK-11A incline, Godavarikhani, in 2002; now widely in SECL, SCCL, Jindal) give 20,000–80,000 t/month.
Longwall face equipment: double-ended ranging drum shearer on an AFC (armoured face conveyor), supported by powered roof supports (chocks), discharging via BSL (beam stage loader) and crusher to the gate belt.
Opencast loaders: rope/hydraulic shovel (electric rope shovels of 10–42 m³ in CIL megaprojects), dragline (24/96, 20/90 class at NCL, MCL for overburden stripping), surface miner (Wirtgen 2200/2500 SM — cuts and sizes coal without blasting, now standard in CIL for selective mining), front-end loader, bucket wheel excavator (NLC lignite mines).
Drills and auxiliaries: rotary blasthole drills (150–311 mm), dozers, motor graders, water sprinklers, crawler cranes.

Underground haulage - rope haulage

Uses tubs/mine cars on a track, pulled by a steel wire rope from a stationary haulage engine. Classified by gradient and rope arrangement:
Direct (single-rope) haulage: one rope, one drum; loaded train hauled up the incline, lowered empty by gravity or by the engine. For gradients up to about 1 in 6; cheap, intermittent.
Main-and-tail haulage: two drums and two ropes — main rope pulls the loaded set one way, tail rope pulls the empty set back. Works on undulating and level roadways and on dips, both directions powered.
Endless rope haulage: a continuous rope loop passes round a driving drum at one end and a return/tension wheel at the other; tubs are clipped to the rope at intervals, giving continuous flow and high capacity over long, uniform roadways.
Gravity (self-acting) haulage: descending loaded tubs raise empties on gradients steeper than about 1 in 8–1 in 10; the engine only brakes.
Chain/scraper and gathering haulage: short-distance gathering of tubs at the face.
Ancillaries: clips and lashing chains, jig/tension wheel, rollers and guide rollers, runaway switch and drag (stop block), safety catches, signalling (bell/telephone — no "blind" hauling permitted).

Underground haulage - locomotives, conveyors and trackless

Locomotives: diesel (flameproof in gassy seams — only with DGMS permission in degree-I/II), battery (storage-battery locos, intrinsically safe, used in Indian coal mines), trolley-wire electric (bare overhead wire — prohibited in coal mine return airways and generally restricted in gassy mines because of arcing). Haulage capacity is limited by adhesive weight, not motor power.
Belt conveyors: the dominant main underground and surface transport. Elements: driving pulley and drive unit, tail pulley, take-up (gravity or winch), troughed carrying idlers (usually 3-roll, 20°/35°), return idlers, belt (fabric NN/EP or steel-cord), snub and bend pulleys, belt scraper/cleaner, holdback brake, skirt boards. Safety fittings required by regulation: pull-cord/emergency stop along the length, belt-slip (speed) switch, belt-sway switch, sequence interlock, fire-resistant antistatic (FRAS) belting, fire detection/water spray at drive heads, and guards at nip points.
Chain conveyors: armoured face conveyor and scraper-chain (panzer) conveyors; rugged, can negotiate slight curves, high power per tonne.
Other: cable belt, aerial ropeway (hilly terrain, Meghalaya/Northeast and cement limestone mines), hydraulic and pneumatic stowing/transport, pipe conveyor for dust-free surface transport.
Trackless (rubber-tyred) haulage: LHD + low-profile dump truck (LPDT), shuttle cars, universal drill rigs — needs good floor, graded roadways, ventilation for diesel exhaust, and DGMS approval for diesel vehicles underground.

Winding and man-riding

Winding (hoisting): drum winders (cylindrical, conical, bicylindro-conical) and friction/Koepe winders (multi-rope, deep shafts; used in deeper Indian shafts). Cages, skips (skip winding for bulk coal) and the keps/chairs, detaching hook (King's/Ormerod) at headgear to prevent over-wind, rope capping, depth indicator, overwind/overspeed protection, automatic contrivance, safety gates.
Winding rope must be of DGMS-approved construction, tested at an approved testing station, with a statutory factor of safety (for man-winding ropes the FOS is high — commonly quoted as 8–9 depending on depth and rope duty class; the exact figure is laid down in the Coal Mines Regulations and the relevant DGMS circulars, so quote the regulation rather than a remembered number).
Man-riding systems: man-riding belt conveyors and chair-lifts in inclines, and man-riding cars on haulages — each needs DGMS permission, dedicated signalling, speed limit, boarding/alighting platforms and stop devices.
Inspection: winding ropes examined daily/weekly, capping re-made at prescribed intervals, winder brakes and safety devices tested daily, and detailed annual examination by a competent person.

Surface and opencast haulage

Shovel–dumper combination: the dominant Indian opencast system; rear-dump trucks of 35 t, 60 t, 85 t, 100 t, 190 t and 240 t matched to shovels of 4–42 m³. Matching rule: 3–5 passes of the bucket should fill the truck.
Dragline and in-pit crushing-conveying (IPCC)/semi-mobile crushers: used where haul distances and diesel cost justify conveyors; CIL has moved to surface miner + conveyor + silo + rapid loading system (SILO/RLS) for rail despatch.
Haul road design: width ≥ 3 × widest vehicle width for two-way traffic, gradient usually kept within 1 in 16 (about 6%) for loaded uphill haul, super-elevation on curves, safety berms, drainage, regular watering and dust suppression; speed limits and TMS (transport management system)/OITDS (operator independent truck dispatch system) at CIL megaprojects (proximity warning, collision avoidance, GPS fleet dispatch).
Ropeways, rail sidings, merry-go-round systems and coal handling plants (CHP) complete the surface chain.

Statutes, standards and maintenance practice

Regulatory frame: the Occupational Safety, Health and Working Conditions Code, 2020 (in force 21 November 2025; it repealed the Mines Act, 1952) with the Coal Mines Regulations, 2017 and the Metalliferous Mines Regulations, 1961, continued under section 143(3) of the Code (draft 2026 successors have been published — check the current text), govern machinery and transport; the OSH&WC (Central) Rules, 2026, which superseded the Mines Rules, 1955 and the Mines Rescue Rules, 1985, add welfare and emergency provisions. The regulator is DGMS (Directorate General of Mines Safety), Dhanbad, under the Ministry of Labour and Employment.
CMR 2017 chapters on haulage and transport require: a system of work/transport rules for every haulage and conveyor, trained and authorised operators, refuge holes at prescribed intervals in haulage roadways, no riding on tubs or belts except on approved man-riding systems, man-riding not to pass under unsupported roof, and prohibition of travel in a haulage roadway while hauling is in progress unless the roadway is of adequate clearance.
Electrical and flameproof requirements: apparatus in gassy seams must be flameproof/intrinsically safe, certified to the relevant IS/IEC explosion-protection standards and DGMS-approved; gas monitoring and methane trip (methanometer) interlocks on face machines.
Mining labour and welfare: the four Labour Codes in force from 21 November 2025 (Code on Wages; Industrial Relations Code; Code on Social Security; Occupational Safety, Health and Working Conditions Code) replaced the Factories, Minimum Wages, Industrial Disputes and BOCW Acts; the OSH Code also repealed the Mines Act, 1952 and is now the mine-safety statute, with the continuing coal and metalliferous regulations as the mine-specific technical law.
Maintenance: planned preventive maintenance (PPM) schedules by running hours, daily/weekly/monthly checks, condition monitoring (vibration, oil analysis, thermography), statutory registers and logbooks, rope and chain registers, and OEM-backed MARC (maintenance and repair contracts) for HEMM in CIL.
Performance measures: availability, utilisation, OEE, MTBF/MTTR, specific fuel/energy consumption, cost per tonne and per BCM.

Key points

Haulage - transport of mineral, men and material from the face to the shaft bottom or surface; it is not loading.
SDL vs LHD - SDL discharges sideways into a tub at the face; LHD loads, carries 50–200 m and dumps, so it needs no tub circuit.
Direct haulage - single rope and drum, hauls up a gradient, suits up to about 1 in 6.
Main-and-tail haulage - two ropes, two drums; powered both ways, works on undulating and level roads.
Endless rope haulage - continuous rope loop, tubs clipped at intervals; highest capacity over long uniform roadways.
Gravity haulage - descending loads raise empties on gradients steeper than about 1 in 8–1 in 10; engine only brakes.
Adhesive weight - the share of locomotive weight on driven wheels; it limits tractive effort, not the motor rating.
Coefficient of adhesion - about 0.2–0.25 on clean dry rail, as low as 0.1 when wet or greasy; sanding improves it.
Rolling resistance - typically 10–15 kg/t on mine rails, 20–30 kg/t for tyres on a good haul road, much higher on soft floors.
Belt conveyor safety fittings - pull-cord stop, belt-slip and belt-sway switches, sequence interlock, FRAS belting, drive-head fire protection.
Troughed idlers - 3-roll, 20°/35°; increase the cross-sectional area of the load and so the capacity for the same belt width.
Surge/take-up - maintains belt tension, absorbs stretch; gravity take-up is self-adjusting.
Detaching hook - a headgear device that detaches and holds the cage if an overwind occurs.
Koepe (friction) winder - multi-rope friction drive, compact, suited to deep shafts; drum winders dominate shallow Indian shafts.
Surface miner - cuts and sizes coal without drilling and blasting, giving low-ash selective mining and less vibration near habitation.
Shovel–dumper matching - truck should fill in 3–5 bucket passes; mismatch destroys fleet productivity.
Haul road gradient - usually limited to about 1 in 16 (6%) for loaded uphill haul; berms, drainage and dust suppression are mandatory practice.
Regulator - DGMS, Dhanbad; the governing law is the OSH Code 2020 (which replaced the Mines Act 1952) with CMR 2017 and MMR 1961.

Formulas and examples

Rope pull (direct haulage, hauling up) P = W(sin θ + μ cos θ) + Wr(sin θ + μr cos θ)
where W = weight of the train (tubs + load), Wr = rope weight, θ = gradient angle, μ = coefficient of rolling/track resistance. For small gradients expressed as 1 in n, sin θ ≈ tan θ = 1/n and cos θ ≈ 1.

Power at the drum P_kW = F × v / 1000 — F = rope pull in N, v = rope speed in m/s. Motor power = P_kW / η (η = haulage mechanical efficiency, typically 0.75–0.85).

Tractive effort of a locomotive F_max = μa × Wa × g — μa = coefficient of adhesion, Wa = adhesive weight in kg, g = 9.81 m/s². The train resistance must be less than F_max.

Train resistance R = W g (r/1000 + 1/n) approximately, with r = rolling resistance in kg/t expressed as N/kN, plus acceleration force = m × a.

Belt conveyor capacity Q (t/h) = 3600 × A × v × ρ × k — A = load cross-section (m²), v = belt speed (m/s), ρ = bulk density (t/m³), k = gradient/fill factor (≤1).
Simplified: Q = 3.6 × q × v, with q = load per metre of belt in kg/m.

Belt power P = (F_total × v)/1000, with F_total from the belt's effective tension; Te = friction + lift terms, and lift power alone = m_t g H / 3600 kW for m_t tonnes per hour raised H metres.

Winding: static load on rope = (cage + car + payload + rope) weight; FOS = breaking strength of rope / maximum static load (must meet the statutory minimum for the duty).
Winding power (peak) = (accelerating force + static unbalanced load) × rope speed / 1000.

Hoisting/haulage duty T (t/h) = payload per trip × 3600 / cycle time (s), cycle time = load + travel + unload + return + delays.

Truck productivity = (payload × 60) / cycle time in minutes t/h; fleet trucks required = shovel output / truck productivity, rounded up.

Example 1 — Direct rope haulage pull and motor power. A direct haulage raises 20 tubs up a 1 in 10 incline. Each tub weighs 350 kg empty and carries 650 kg of coal. Track resistance = 1/50 of the normal load. Rope weighs 2.2 kg/m, incline length 600 m, rope speed 2.0 m/s, haulage efficiency 80%.

Train mass = 20 × (350 + 650) = 20,000 kg. Rope mass = 2.2 × 600 = 1,320 kg. Total = 21,320 kg.
Gradient force = 21,320 × 9.81 × (1/10) = 20,915 N.
Resistance force = 21,320 × 9.81 × (1/50) = 4,183 N.
Rope pull F = 20,915 + 4,183 = 25,098 N ≈ 25.1 kN.
Power at drum = 25,098 × 2.0 / 1000 = 50.2 kW; motor power = 50.2/0.80 = 62.7 kW → select a 75 kW haulage motor.

Example 2 — Locomotive adhesion check. A 12 t battery locomotive (all wheels driven) hauls 25 mine cars of 2.0 t gross each on a level track. Rolling resistance 12 kg/t, coefficient of adhesion 0.20, required acceleration 0.05 m/s².

Train mass behind loco = 25 × 2.0 = 50 t; total moving mass = 62 t = 62,000 kg.
Rolling resistance = 12 kg/t × 62 t = 744 kg force = 744 × 9.81 = 7,299 N.
Acceleration force = 62,000 × 0.05 = 3,100 N.
Total required effort = 7,299 + 3,100 = 10,399 N ≈ 10.4 kN.
Available tractive effort = 0.20 × 12,000 × 9.81 = 23,544 N ≈ 23.5 kN.
10.4 kN < 23.5 kN, so the locomotive can haul the train (margin ≈ 2.3×). If the coefficient falls to 0.10 on wet rail, available effort = 11.8 kN — still just adequate on the level, but it would fail on any rising gradient.

Example 3 — Belt conveyor capacity and power. A 1,000 mm belt runs at 2.5 m/s carrying coal of bulk density 0.85 t/m³. Measured load cross-section 0.055 m², fill factor 0.9. Belt length 800 m along a 1 in 12 rise; effective tension computed as 28 kN.

Capacity Q = 3600 × 0.055 × 2.5 × 0.85 × 0.9 = 378.7 t/h (≈ 379 t/h, about 9,000 t in a 24-hour day at full load).
Belt power at drive pulley = 28,000 × 2.5 / 1000 = 70 kW; at 90% drive efficiency the motor ≈ 77.8 kW → select 90 kW.
Check the lift component: vertical rise H = 800/12 = 66.7 m; lift power = 378.7 × 9.81 × 66.7 / 3600 = 68.8 kW — so lifting dominates, which is why conveyor inclines are kept gentle (coal belts generally stay within about 16–18° to avoid material rollback).

Example 4 — Shovel–dumper matching. A 10 m³ shovel with bucket fill factor 0.85 and swing cycle 32 s loads 60 t rear-dump trucks. Coal bulk density in bucket 1.5 t/m³. Truck cycle: haul 2.4 km at 20 km/h loaded, return at 30 km/h empty, spot + dump + queue 3.0 min.

Payload per bucket pass = 10 × 0.85 × 1.5 = 12.75 t → passes per truck = 60/12.75 = 4.7 → 5 passes (good match, within 3–5).
Loading time = 5 × 32 s = 160 s = 2.67 min.
Haul time = 2.4/20 h = 0.12 h = 7.2 min; return = 2.4/30 h = 0.08 h = 4.8 min.
Total truck cycle = 2.67 + 7.2 + 4.8 + 3.0 = 17.67 min.
Truck productivity = 63.75 t (5 × 12.75) × 60/17.67 = 216.5 t/h.
Shovel capability = 12.75 t per 32 s = 1,434 t/h theoretical; at 0.75 operating efficiency ≈ 1,076 t/h.
Trucks needed = 1,076/216.5 = 4.97 → 5 trucks to keep the shovel busy (6 if one spare is kept for availability).

Example 5 — Winding rope factor of safety. A single-rope drum winder lifts a cage of 2,500 kg carrying 12 persons at 75 kg each from 450 m. Rope mass 3.6 kg/m, rope breaking strength 900 kN.

Payload = 12 × 75 = 900 kg. Rope mass = 3.6 × 450 = 1,620 kg.
Total suspended mass = 2,500 + 900 + 1,620 = 5,020 kg → static load = 5,020 × 9.81 = 49.25 kN.
FOS = 900 / 49.25 = 18.3 against static load — comfortably above the statutory minimum for man-winding (the required figure is prescribed in the Coal Mines Regulations and DGMS circulars and varies with depth and duty, so it must be read from the current text rather than assumed).

System	Capacity	Distance suited	Gradient	Flexibility	Typical Indian use
Direct rope haulage	Low, intermittent	Up to ~1 km	Up to 1 in 6	Low	Old bord-and-pillar inclines
Main-and-tail	Medium	1–2 km	Undulating, both ways	Medium	Developing districts
Endless rope	High, continuous	2–5 km	Uniform, gentle	Low	Long main inclines
Locomotive	High	Long levels	Up to ~1 in 50	Medium	Shaft-bottom levels, metal mines
Belt conveyor	Very high, continuous	Unlimited in flights	Up to ~16–18°	Low once laid	CM and longwall panels, CHP
LHD/LPDT trackless	Medium-high	50–500 m / 1–2 km	Up to 1 in 8	Very high	Metal mines, mechanised coal
Shovel–dumper	Very high	1–5 km	Up to 1 in 16	Very high	All CIL opencast mines

Where it is used

Coal India subsidiaries (ECL, BCCL, CCL, NCL, WCL, SECL, MCL, NEC) and SCCL: mine foreman, overman, mining sirdar, mining engineer and E&M engineer roles planning haulage layouts, belt flights and HEMM fleets; draglines at NCL/MCL, surface miners and SILO/RLS despatch across CIL.
Metal and non-coal mines: NMDC (Bailadila conveyors and downhill ropeway/slurry transport), Hindustan Zinc (Rampura Agucha, Sindesar Khurd — trackless LHD, LPDT, shaft winding), Hindustan Copper (Malanjkhand), Tata Steel and JSW iron ore mines.
Equipment OEMs and service companies: BEML, Caterpillar, Komatsu, Liebherr, Sandvik, Epiroc, Wirtgen, Thyssenkrupp, TRF, Elecon, Fenner/Continental belting — design, application engineering, product support, MARC contracts.
Mine Developer and Operator (MDO) contractors and consultants: Adani Enterprises, Thriveni Earthmovers, Sainik Mining, CMPDI, MECON — fleet sizing, haul road design, conveyor and CHP engineering.
Regulation, inspection and training: DGMS inspectorate, mine rescue stations, IIT (ISM) Dhanbad and the DGMS gas-testing/competency examinations where haulage and machinery regulations are directly tested.
Cement, limestone and aggregate quarries: shovel–dumper, in-pit crushers, long overland and pipe conveyors at UltraTech, ACC-Ambuja, Dalmia and Shree Cement captive mines.

Interview questions

Q: What is the difference between haulage and winding? A: Haulage moves material horizontally or along an incline inside the mine or on the surface; winding raises and lowers it through a vertical or steep shaft using a cage or skip.
Q: Which haulage would you choose for a long, gently undulating main roadway with high output, and why? A: Endless rope haulage or, better, a belt conveyor — both give continuous flow; a belt is preferred for high tonnage because it has lower labour, fewer accidents and no tub circuit.
Q: Why is adhesive weight more important than motor power for a locomotive? A: Tractive effort is limited by friction between driven wheels and rail (μa × adhesive weight); beyond that the wheels simply slip however powerful the motor is.
Q: What are the statutory safety devices on an underground belt conveyor? A: Pull-cord emergency stop along its length, belt-slip (under-speed) and belt-sway switches, sequence interlocking, fire-resistant antistatic belting, fire detection and water spray at the drive head, and guarding of nip points.
Q: What does a detaching hook do? A: On overwind it detaches the rope from the cage at the headgear and simultaneously suspends the cage from the catch plate, preventing the cage from crashing into the headgear or falling.
Q: Why is a surface miner preferred in many CIL opencast mines? A: It cuts and sizes coal in one pass without drilling and blasting, giving selective low-ash coal, no blast vibration or flyrock near villages, and a product that needs no primary crushing.
Q: How do you decide the number of dumpers for a shovel? A: Compute truck cycle time and productivity, compute the shovel's achievable output, divide one by the other and round up, then add spares for availability; check the 3–5 bucket passes per truck matching rule.
Q: Why are refuge holes required in haulage roadways? A: So a person caught in the roadway while hauling is in progress has a place to stand clear of the moving tubs or rope; they must be at prescribed intervals, whitewashed and kept clear.
Q: What limits the inclination of a coal belt conveyor? A: The angle of repose and friction of the material — above roughly 16–18° coal rolls back on a plain troughed belt; steeper duties need cleated, sidewall or sandwich belts.
Q: Compare SDL and LHD. A: An SDL is cheaper, needs less roadway width and discharges sideways into a tub at the face; an LHD carries the load itself to a tipping point, gives higher output and flexibility, but needs a graded floor and wider roadways.
Q: What checks are made daily on a winding installation? A: Visual examination of the winding rope and capping, testing of brakes, overwind and overspeed devices, signalling and safety gates, with entries in the statutory register by the appointed competent person.
Q: How does methane monitoring interlock with face machinery in a gassy seam? A: A methanometer at the machine trips power to the machine when methane exceeds the prescribed percentage; equipment must additionally be flameproof or intrinsically safe and DGMS-approved.

Common mistakes

Omitting the rope weight in a haulage pull calculation, or forgetting that on a gravity haulage the rope weight helps rather than hinders.
Confusing gradient 1 in n with an angle in degrees, and using sin θ where the stated resistance is already a fraction of the normal load.
Sizing a locomotive from motor power alone and ignoring the adhesion limit, then wondering why wheels spin.
Mixing units in conveyor work — kg/m with t/m³, m/min with m/s, kg force with newtons.
Quoting an availability figure without its denominator (scheduled hours) so utilisation and availability get interchanged.
Treating a factor of safety as if it applied to the breaking load of the rope only against the payload, leaving out cage, car and rope mass.
Describing man-riding on belts or tubs as normal practice; it is permitted only on specially approved systems with their own devices and rules.