1. Cranes

  • Function/Uses: Cranes are machines designed for lifting, lowering, and horizontally moving heavy loads, utilizing a projecting arm (boom or jib) and a hoisting mechanism (ropes/chains and hook). They are indispensable in construction for erecting structures (steel, precast concrete), lifting building materials, placing heavy equipment (like HVAC units), bridge construction, industrial maintenance, and port operations.
  • Variations: Cranes are broadly categorized as Static or Mobile, with numerous types within each group (See Section IV.D for detailed comparison).
    • Static Cranes: Remain in a fixed location during lifting operations.
      • Tower Cranes: The defining crane type for high-rise building construction. Consist of a vertical mast anchored to the ground or building structure, a slewing unit allowing rotation, a horizontal or luffing jib (arm), a counter-jib with counterweights, a trolley (on hammerheads) to move the hook along the jib, and the hoist mechanism.4 Types include Hammerhead (fixed-level jib), Luffing Jib (jib raises/lowers, better for confined sites), Self-Erecting (smaller, faster setup for lower-rise projects), and Level Luffing (specialized).
      • Gantry Cranes: A bridge beam supported by legs that travel on wheels or rails on the ground. Straddle the work area. Common in shipyards, precast yards, and large outdoor industrial sites.
      • Jib Cranes: A horizontal jib arm, typically rotating, attached to a building wall or a floor-mounted pillar. Provide localized lifting within a specific radius.
      • Overhead Cranes (Bridge Cranes): Similar to gantry cranes but the bridge travels along elevated runway beams, typically inside buildings like factories or warehouses.
    • Mobile Cranes: Mounted on chassis allowing movement around the site or between locations. Require outriggers for stability during lifts.
      • Crawler Cranes: Mounted on tracks, offering high lifting capacity and excellent stability on soft or uneven ground. Require transport and assembly/disassembly between sites.
      • All-Terrain Cranes: Multi-axle wheeled chassis suitable for both public roads (at highway speeds) and rough job site terrain. Offer high capacity and versatility.
      • Rough-Terrain Cranes: Compact, wheeled chassis with large tires and 4-wheel drive/steering, designed specifically for off-road site maneuverability. Typically not road legal for long distances.
      • Truck-Mounted Cranes (Boom Trucks): Crane upper structure mounted on a standard commercial truck chassis. Road legal, quick setup, good mobility, generally lower capacity than specialized mobile cranes.
      • Carry Deck Cranes: Small, four-wheeled cranes with a rotating boom and a load deck. Designed for pick-and-carry operations within a confined site.
      • Knuckleboom Cranes (Loader Cranes): Feature an articulated boom that folds compactly, often mounted on trucks for loading/unloading materials like logs, blocks, or equipment.
  • Components: Core components include the boom (lattice structure or hydraulic telescopic sections), jib (extension attached to boom tip), hoist mechanism (winches, ropes/cables, sheaves), hook block, slewing mechanism (allows rotation), counterweights (provide stability), supporting structure (mast, chassis, tracks, wheels), operator cab, and outriggers (for mobile cranes). The selection of crane type is a critical project decision, balancing lifting requirements (capacity, height, radius) against site conditions, project duration, mobility needs, and cost.

2. Aerial Lifts / Mobile Elevating Work Platforms (MEWPs)

  • Function/Uses: MEWPs are mobile machines designed to provide temporary access for people, tools, and small amounts of material to work areas at height. They are widely used in construction for tasks like steel erection connections, facade installation (cladding, windows), painting, electrical work, plumbing, HVAC installation, maintenance, and inspections. They offer a safer and often more efficient alternative to scaffolding or ladders for many tasks.
  • Variations: The main types differ in their lifting mechanism and reach capabilities (See Section IV.E for detailed comparison):
    • Boom Lifts: Feature a work platform attached to the end of an extendable arm (boom) mounted on a mobile base.
      • Articulating Boom Lifts (Knuckle Booms): Have multiple hinged sections in the boom, allowing them to articulate "up and over" obstacles. Ideal for reaching into complex structures or congested areas.
      • Telescopic Boom Lifts (Stick Booms): Have a straight boom that extends telescopically. Offer the greatest horizontal and vertical reach but lack the up-and-over capability of articulating booms. Best for accessing distant points in open areas.
    • Scissor Lifts: Utilize a series of linked, folding supports (scissor mechanism) beneath the platform to lift it vertically. They offer larger platform sizes and higher weight capacities than boom lifts but are limited primarily to vertical movement. Some models have deck extensions for minor horizontal reach.
    • Personnel Lifts (Single Man Lifts / Vertical Mast Lifts): Compact lifts designed to elevate a single worker with minimal tools directly upwards. Often used for maintenance or light installation tasks in tight spaces.
  • Components: Include a mobile base/chassis (typically wheeled, sometimes tracked), the lifting mechanism (boom sections with hydraulic cylinders, or scissor arms), a work platform with safety railings and controls, and a power source (commonly electric for indoor/quiet use, or diesel/dual fuel for outdoor/rough terrain use). The choice between lift types depends crucially on the required reach (height and outreach), the presence of obstacles, platform size/capacity needs, and site conditions (indoor/outdoor, terrain).