7.5 Mobile Cranes, Tower Cranes & Offshore Cranes
Key Takeaways
- Mobile-crane capacity depends on the exact boom, radius, counterweight, reeving, support, sector and attachment configuration shown by the chart.
- Outrigger extension and pick-and-carry are permitted only under the crane-specific chart and manufacturer conditions, with verified ground and route support.
- Tower-crane foundations, ties, climbing systems and erection states are safety-critical and require engineered procedures and installation-dependent examination.
- Offshore pedestal cranes operate under dedicated ratings and sea-state limits that address vessel motion and other dynamic effects.
- LOLER permits a competent-person scheme or default intervals of 12 months for lifting equipment and six months when used to lift people, plus examination after relevant exceptional circumstances.
Mobile Cranes, Tower Cranes and Offshore Cranes
Mobile and site cranes differ in structure and environment, but the controlling principles are consistent: use the rated capacity for the exact configuration, establish adequate support, account for the operating environment and plan the lifting operation.
1. Mobile Cranes
| Type | Characteristics | Typical deployment |
|---|---|---|
| Yard crane | Small mobile crane used within industrial premises | Plant and yard handling |
| Truck-mounted crane | Crane carrier designed for road relocation | General crane hire and utilities |
| Rough-terrain crane | Compact site crane designed for uneven terrain | Construction and industrial sites |
| City crane | Compact mobile crane for restricted space | Urban maintenance and construction |
| All-terrain crane | Multi-axle crane combining road travel and site capability | Larger mobile lifts |
| Loader crane | Articulating or telescopic crane mounted on a goods vehicle | Loading and unloading its vehicle |
Configuration Controls
A mobile crane load chart is conditional. Boom length, radius, counterweight, reeving, outrigger or tyre configuration, working sector, attachments and wind can all change capacity. Include the hook block and lifting accessories where the chart defines gross load. A rated-capacity limiter is an aid, not permission to omit the chart or lift plan.
Outriggers must be set exactly as the selected chart requires. Some cranes publish reduced-capacity charts for partial extension; others require full extension. Ground bearing capacity, underground services, voids, trenches and recent excavation must be assessed. Mats or engineered spreaders distribute reaction only when they are correctly sized and supported.
A rough-terrain crane may travel with a suspended load only when the manufacturer's pick-and-carry chart and conditions allow it. Those conditions may restrict boom position, radius, tyre pressure, travel speed, route gradient and load height. “Rough terrain” does not mean unrestricted travel over poor ground.
2. Tower Cranes
A tower crane normally has a mast, slewing unit, jib, counter-jib, trolley or luffing system, hoist and counterweights. Capacity changes with radius and configuration. Foundations, ties, climbing frames, bolts and mast sections form part of the safety-critical load path.
Erection, alteration, climbing and dismantling require engineered procedures, competent supervision and control of wind. Where safety depends on installation or assembly, LOLER requires thorough examination after installation and before use at that location. Zoning, anti-collision systems and limits may control interaction with other cranes or protected spaces, but physical and procedural planning remain necessary.
3. Offshore Pedestal Cranes
An offshore pedestal crane is a pedestal-mounted, elevating and rotating lifting device used to transfer loads to or from vessels, barges or offshore structures. Vessel motion, wind and sea state add dynamic effects not present in an ordinary static land lift. The crane's offshore standard, operating chart and management system define dynamic factors, offboard/onboard ratings and environmental limits.
Personnel transfer is a specialised operation requiring purpose-designed equipment, procedures and authorisation. Constant-tension or motion-compensation functions exist on some cranes, not all. Their presence does not remove sea-state limits or the need for competent planning.
4. Examination and Records
LOLER permits either intervals set by a competent-person examination scheme or the default periodic intervals. For lifting equipment not used to lift people, the default is 12 months; equipment used to lift people is normally six months. Examination is also required after exceptional circumstances liable to jeopardise safety. Equipment whose safety depends on installation or assembly must be examined after that installation or assembly and before use.
A thorough examination may address structure, ropes, hooks, brakes, limits, rated-capacity devices, supports and installation-dependent parts. The competent person decides the extent and any test or NDT needed; routine overload testing and NDT on every component are not automatic LOLER requirements. Reports, declarations, maintenance information and outstanding defects must be controlled under their applicable retention rules.
5. Planning the Lift
A safe plan establishes load mass and centre of gravity, crane configuration, radius and route, rigging, support reactions, environmental limits, exclusion zones, communications and foreseeable failure or recovery actions. It also addresses nearby structures, overhead conductors, public interfaces and simultaneous operations.
Weather is not a single universal wind-speed rule. The crane manual, load area, boom and jib configuration, erection state and site conditions determine limits. Large panels can exceed a crane's permissible wind effect even when their mass is well within the chart.
Before the main lift, verify configuration and safety devices, complete required pre-use checks and make a controlled trial lift where appropriate. Stop if the load, radius, ground, wind or communication differs from the plan. Whether the crane is a loader crane, tower crane or offshore pedestal crane, its capacity is valid only inside the conditions used to establish that rating.
Which mobile crane type is mounted to a truck behind the cab or deck and is used to deliver goods exactly where required without a separate forklift or crane?
What distinguishes a rough-terrain crane, and when may it travel with a suspended load?
How is an offshore pedestal crane defined, and what is its purpose?