£ £ Horizontal jib tower crane assisted erect
£ £ This configuration of crane is widely used in the construction industry. It requires assistance in erection and this is usually provided by a suitable sized mobile crane, erection times vary but on average a time of two to three days can be expected for a crane of thirty metres square.
£ £ Erection of this type of crane is normally carried out by a crew and an engineer, trained in the specific erection procedures required. At the conclusion of the erection the crane will be subjected to a thorough examination and an application of a 25% overload followed by the setting of the safety devices.
£ £ Jibs of 50m and longer are available for applications where greater area coverage is required, and tower heights of up to 180m can be readily found for the project that needs this sort of lift height. A range of hoist and trolley winches are offered by the crane manufacturers, providing the crane user with a wide choice of hook speeds and pull combinations. Rail-mounted bases are often available for this type of crane.
£ £ Cranes of this type are excellent in the role of rapid light weight material handling and when correctly sited and driven will provide comprehensive and efficient lifting services for a large area of a site. Though not usually of very large maximum lifting capacity, average construction industry capacities being between 5000kg and 10000kg, the horizontal jib tower crane can lift its maximum capacity out to a radius in excess of 25% of its total, and at maximum radius a healthy capacity still remains.
£ Lifting jib tower crane assisted erect
This configuration of crane tends to be used where special circumstances exist that would restrict the use of a horizontal jib tower crane. The main advantage of a luffing jib is that both jib and suspended load can be kept from over areas where there intrusion is not wanted.
£ £ As far as its erection is concerned it follows the same lines as the assisted erect horizontal jib tower crane discussed previously, each erection being followed by a thorough examination and test.
£ £ Jib lengths, tower heights and winch types, as with horizontal jib cranes, are available for selection by the user, so as to be able to customise the crane to the lifting environment and requirements. This configuration is not as quick as the horizontal jib crane, particularly when the lifting operation requires frequent radius alterations, the luffing winch having to move the weight of both the load and the jib; also alteration of the load radius is accompanied by a change in load height which must be compensated for by the operator if level luffing is required. Some winch units can do this automatically but of course they are more expensive.