The true self erect tower crane is smaller and of lower capacity than its assisted erect counterpart, but has the great advantage of being quick and easy to erect. The erection procedure is well within the capability of a trained fitter or competent driver and the newly erected crane does not have to undergo the sort of comprehensive commissioning procedures required by an assisted erect crane.
In recent years there has been a move toward tower cranes that are quick to erect, but the small size and capacity of the self erect crane has always proved a barrier to its usefulness on most construction sites. Tower crane manufacturers are now producing a design of crane which embodies the best features of both the self erect and assisted erect tower cranes. Called the ¡®City Crane¡¯, these machines can be erected quickly and have a size and capacity which makes them an attractive proposition for use on general construction sites.Some self erect tower cranes are mounted on a crawler track base and with the provision of an on-board generator and independent of an external power supply. These cranes have the abilty to be extremely mobile around a site, travelling fully erected without a load. Whatever their base type, self erect cranes usually require the use of outriggers which are used to both support and level the crane during lifting operations. Because of their importance to crane stability, outriggers should be checked by the driver frequently for security and level.
