India's Most Trusted Source for Industrial Cranes — 200+ Verified Manufacturers, IS 3177 / IS 807 Certified EOT, Gantry, Jib & Goliath Cranes, SWL 1–500 MT

What is an EOT crane and how does it differ from a gantry crane?

An EOT (Electric Overhead Travelling) crane is an overhead crane in which the bridge structure (one or two girders spanning the bay width) travels on elevated runway rails mounted on the building structure (on brackets fixed to the building columns, or on dedicated crane gantry columns); the crane bridges the bay width and travels along the bay length on the elevated rails; the hoist and crab travel across the bridge span; together, the three motions (long travel on runway, cross travel on bridge, hoist up/down) allow the hook to reach any point within the crane's rectangular coverage area; the crane hangs from the building structure — the elevated rails transfer the crane loads to the building columns; a gantry crane is a self-supporting crane that does not need a building structure for support; it has two legs (an inverted-U structure) that support the crane bridge; the legs have wheels that travel on ground-level rails or a paved surface; the gantry is freestanding and can be used: outdoors in an open yard where there is no building structure above; in a building that does not have adequate structural members at high level to support an overhead crane; for temporary use that will be relocated; key differences: EOT requires a building structure to support the runway — if the building is not designed for crane loads, runway beams and building column strengthening may be needed; gantry requires only a flat ground surface with rails — simpler and more flexible for outdoor or temporary applications; EOT has lower self-weight per unit SWL than a gantry (the A-frame legs of a gantry are significant additional weight); gantry has greater accessibility under the crane (the legs block some areas — the EOT has no legs below the runway level and provides full floor accessibility under the crane path); for standard manufacturing plants with overhead structural steel: EOT is the standard choice; for outdoor yards, fabrication areas, or existing buildings without crane runway capability: gantry is appropriate.

What is SWL and what is the difference between SWL and WLL?

SWL (Safe Working Load): the maximum load that a crane or lifting device is designed and authorised to lift during normal operation; it is a regulatory and design term used in Indian standards and the Factories Act; the SWL is the maximum load the crane's structure, hoist mechanism, wire rope, hooks, and all other components are designed to carry with the required safety factor; it is marked on the crane bridge, on the hook block, and on the Certificate of Test and Thorough Examination; the SWL must never be exceeded during normal operation; WLL (Working Load Limit): the internationally used equivalent of SWL — the maximum working load of the crane or lifting tackle; used in ISO and European standards; in practice, SWL and WLL are the same concept with different terminology; the proof load (test load): the crane is proof-loaded to 1.25× SWL before being put into service (Factories Act requirement); this verifies that the crane has adequate structural reserve; the proof load is a one-time test load — it is NOT the operating load; the crane's operating limit remains the SWL after proof-loading; the breaking load: the load at which the crane component would structurally fail; the design safety factor specifies the minimum ratio of breaking load to SWL: for wire ropes in crane service: minimum safety factor 5 (IS 3938) — meaning the wire rope MBL must be at least 5× the rope's working tension under SWL; for crane hooks: safety factor 4 against static yield under 2× SWL test load; these safety factors provide the reserve capacity that protects against dynamic overload, wear, and fatigue over the crane's service life; practical implications: a crane marked SWL 10 MT must not be used to lift a load estimated at 10 MT without verification of the actual load weight; if the actual load weight is uncertain: weigh the load before lifting using a load cell in the hook block; do not guess.

What is IS 3177 duty class and which class do I need?

IS 3177 is the Indian standard that classifies cranes by their 'duty' — the combined effect of how frequently the crane is used (utilisation class) and how heavily it is loaded relative to its SWL (state of loading); together these determine the crane's duty class (M1 through M8), which governs the structural design of the crane (heavier duty classes require larger girder sections, more robust connections, and more fatigue-resistant welds). Quick reference guide: M2 — HOT (hand-operated) cranes; maintenance cranes in power plants; cranes used a few times per day at low load; M3 — workshop cranes; occasional production use; 5–10 lifts per hour at 20–40% of SWL; M4 — general production; manufacturing with regular (but not intensive) use; 10–20 lifts per hour at 30–50% of SWL; M5 — busy production crane; fabrication shops; regular use at medium to heavy loads; 15–25 lifts per hour at 40–60% of SWL; M6 — heavy-duty production; steel service centres; continuous manufacturing; 25–40 lifts per hour at 50–70% of SWL; M7 — very heavy duty; foundry cranes; charging cranes; hot metal handling; effectively continuous operation at 60–80%+ of SWL; M8 — metallurgical process cranes; ladle cranes; teeming cranes; operated near continuously at or near 100% of SWL; selection error cost: the cost difference between M4 and M7 for a 10 MT, 20 m span crane is approximately Rs.3–5 lakh (15–25%); the cost of replacing an M4 crane that fails prematurely due to fatigue (at 4–5 years instead of 20+ years) is the full replacement cost plus the cost of the production shutdown during the failure and replacement period — far exceeding the cost of the correct M7 specification from the beginning; always use the conservative (higher) duty class when in doubt.

What is an explosion-proof crane and when is it required?

An explosion-proof crane is an overhead crane whose electrical components (motors, controls, pendant station, limit switches, lighting if fitted) are constructed to prevent them from igniting a surrounding flammable atmosphere; the term 'explosion-proof' is commonly used to describe several different protection methods that achieve this safety objective by different means. When it is required: any crane installed in a hazardous area (classified Zone 0, 1, or 2 for gas/vapour hazard; Zone 20, 21, or 22 for dust hazard) requires Ex-rated electrical equipment; common hazardous area locations in India: chemical plant process areas (Zone 1); petroleum refineries and LPG storage (Zone 1 and 2); solvent-based paint spray booths (Zone 1); pharmaceutical active ingredient manufacturing (Zone 1 or 2 for flammable solvent handling); grain silos (Zone 21); flour mills (Zone 21); fertiliser plants; the area classification must be determined by a hazardous area classification study (typically conducted by the plant's safety engineer or a specialist consultant per IS 5572 — Classification of Hazardous Areas); the crane specification must match the zone classification: Zone 1: minimum Ex-d (flameproof) or Ex-e (increased safety) protection for motors and control panels; all electrical components rated for Zone 1 (Category 2G); Zone 2: Ex-nA (non-sparking) may be adequate for Zone 2; Ex-d or Ex-e provides additional safety margin; the Ex-rating must be verified by a CCOE approval certificate for petroleum installations, or by a PESO-recognised test house certificate for other hazardous area applications; cost premium: explosion-proof cranes typically cost 40–70% more than standard cranes of the same SWL and configuration; this premium is mandatory and not negotiable for hazardous area applications.

What is the proof load test and why is it mandatory?

The proof load test (also called the overload test or load test) is a mandatory pre-service test in which the crane is loaded to 1.25× its rated Safe Working Load (SWL) — for a 10 MT SWL crane: 12.5 MT proof load — to verify that all structural and mechanical components can sustain loads above the rated SWL without permanent deformation or damage. Why 1.25×? The design safety factor for crane structures under IS 807 is based on the crane not experiencing loads above 1.25× SWL during its service life; the proof load test verifies that this safety reserve actually exists in the as-fabricated and as-installed crane (fabrication defects, material sub-standard, design calculation errors — all can reduce the actual strength below the design strength; the proof load test catches these problems before the crane goes into service); what the proof load test checks: structural: the girder, end carriages, and crab frame are examined before and after the proof load for permanent deformation (if the deflection under the proof load does not return to zero after the load is removed, the structure has been permanently deformed — indicating yield stress was exceeded — this is a failure; the crane must be repaired and re-tested); mechanical: the hoist mechanism (drum, gears, bearings, brake) is examined during and after the proof load test for overheating, abnormal noise, or slippage; electrical: the motors and drives are checked for current and temperature under the proof load; legal requirement: the Factories Act 1948 Section 29 and the applicable state Factories Rules require the proof load test before any crane is put into service; the Certificate of Test and Thorough Examination (issued by the factory's competent person after the proof load test) must be kept at the factory and produced for the Factories Inspector on demand; the certificate must be renewed annually (after each annual statutory load test); a crane operating without a current certificate is in violation of the Factories Act.