Hoist Systems and Their Mechanisms

Electric Chain and Wire Rope Hoists

• Modern electric hoists use low voltage control (24-50V AC/DC) derived internally via a transformer.
• Some older or specialized hoists do not use low voltage control, instead utilizing mains voltage control.
• Common lifting media for power-operated hoists includes short link round steel chain, steel wire rope, and HMPE/textile belt materials.
• Chain hoists' chain hangs loose, often housed in a box, which limits the lift height.
• Wire rope hoists use a drum to store wire rope, with the lift limited by the amount of rope on the drum.

Pneumatic Hoists

• Pneumatic hoists are less versatile than electric hoists, primarily due to air supply limitations.
• They frequently are used where air supplies already exist and safety is a concern.

Hydraulic Hoists

• Hydraulic hoists deliver smooth, accurate lifting and lowering, and are quiet in operation.
• An electric motor drives a hydraulic motor, which converts hydraulic pressure/flow into torque/rotation to move the hoist.
• Electric motors do not need to be physically near the hydraulic drive making the system virtually noiseless.
• Hydraulic hoists are frequently used in intrinsically safe areas like pneumatic hoists.

Electrical Controls

• Additional controls like radio or infrared controls enhance remote or central control, especially in areas of limited access.
• Multi-point controls (often wall-mounted) permit control from numerous locations, useful for operations across multiple floors.
• Interlocking mechanisms are crucial for these multi-point setups, to prevent simultaneous operation.
• Emergency stop buttons are included to override all control positions and require manual reset.

Supporting Structures for Hoists and Light Crane Systems

• Runways provide a track for lifting appliances and allow for loads to be raised, lowered, and moved along the path.
• Runways can be manufactured from standard or special rolled steel sections, supported by building structures, dedicated free-standing structures, or a combination of both, and offer an economical alternative to overhead traveling cranes. -Built-in runways are supported by existing building structures with "simply supported" and "encastred" types.
• Suspended runways can also be suspended from roof members or beams built into the building structure.
• Free-standing runways are used where no existing supports are available.
• Special track systems (often kits for light crane systems) are flexible and offer various configurations including switches, turntables, etc, and even low capacity bridge cranes.

Switches and Turntables

• Runway switches and turntables allow the lifting appliance to be transferred from one runway system to another.

Slewing Jib Cranes

• Slewing jib cranes are frequently utilized in industry for lifting and limited moving operations.

Mobile Gantries

• Mobile gantries are a free-standing structure, comprising a runway beam and supports (often 'A' frames) mounted on wheels.
• They are often used in areas where permanent installations are not cost-effective.
• A goalpost gantry consists of a runway beam with single column supports, offering limited light load capacity (typically up to 500kg).
• A frame gantry is a common mobile design. It uses 'A'-frame supports for lateral stability in a range of capacity (frequently up to 5 tonnes).

Adjustable Height Gantry

• Adjustable height gantries utilize telescopic supports to accommodate varying site conditions without needing to be moved, and only raise or lower to match load requirements.

Internally Braced Gantry

• Internally braced gantries are assembled horizontally on the floor using winches to bring the 'A'-frame supports together before securing them.

Foldaway Gantry

• Designed for ease of disassembly and storage for infrequent use and are usually up to 2 tonnes.

Crane Supporting Structures Tracks (Gantries) and Tracks

• Cranes are commonly manufactured from standard sections, with a rail often welded to the top flange.
• Underslung cranes use the bottom flange or directly to the supporting columns.
• Some cranes have intermittent welding for structural purposes whilst other rails are clamped firmly.

Bridge and Gantry Cranes

• Bridge and gantry cranes enable load transportation/movement.
• Top running bridge cranes run on top of rails, part of the crane structure, while under-slung cranes run along a lower rail section.
• Portal Bridge Cranes have girders supported via legs positioned on a lower level track
• Semi-portal bridges combine elements of top-running and portal designs.

Top Running Bridge Crane

• Distinguished by running on rails embedded within the crane support structure.

Under-Slung Bridge Crane

• Distinguished by their under-slung arrangement, which can allow for cantilevered ends and multiple cranes on parallel tracks.

Portal Bridge Crane

• Distinguished by running on lower-level tracks and using legs to support the bridge girder.

Semi-Portal Bridge Crane

• Combines the features of top running and portal cranes; often using legs and a cantilever arrangement.