Certain factors affect the type of crane you are looking for to complete a certain job. Some, like a tower crane, are fixed in location. Tower cranes bear large loads at the expense of mobility. Others, like many mobile cranes, are movable but relatively difficult to navigate through close spaces. Spider crane hire offers a cost-effective and realistic solution to crane work in tight spaces.
Below is an explanation of tower cranes, mobile cranes, and spider cranes. The uses, potentials, and abilities are all compared. The goal is to determine whether a tower crane or a mobile crane is best for your needs.
The Tower Crane
Tower cranes assist in the construction of tall buildings. Tower cranes contain three parts. One, the long horizontal jib or working arm contains the trolley and hoist which lift the construction materials. The horizontal jib bears the load of the construction materials. Another, the counter-jib, contains a counter-weight of concrete blocks. The counter-jib offsets the horizontal jib, allowing the working arm to pivot around the turntable attached to the mast. A cab, positioned on the turntable or down the mast, controls the pivoting of the crane and the lifting of materials.
Alternately, the operation of the tower may be conducted by remote control. However, it’s easier for an operator in the cab to see the positioning of the hook. A signaller at the bottom of the crane is responsible for the rigging and loads as well as the timing of lifts for the job.
The Mobile Crane
A mobile crane sits atop a truck or is self-propelled. The end of the boom contains a hook suspended by wire rope and sheaves. The boom itself is often telescopic. At various times steam, electric, and internal combustion engines all powered mobile cranes. Today, torque converter transmissions, rather than clutches, control the transmission.
Spider cranes are mini cranes designed to be used indoors or outdoors in confined areas. Spider cranes can fit through doorways, and have heights as high as 21 metres (m). Spider cranes have different attachments to lift glass or provide searcher hooks. These cranes are also lighter than tower cranes and different types of motorised mobile cranes.
Some spider cranes can be controlled remotely, leaving the operator a better view of an otherwise hazardous worksite. Spider cranes are propelled by gas, diesel, or electricity. Spider cranes are best for places with site disruption and road closures.
Load Weight to Be Lifted
The average tower crane can lift anywhere from 9 to 20 metric tons (t). Mobile cranes can lift anywhere from 10t to 60t. Spider cranes lift from 1.7t to 6t. Hydraulic cranes can lift from 2.93t to 6t.
There is no ideal crane for every job. Rather, you have to look at aspects such as the loading deck and the crane. A loading deck is an extendable platform used alongside cranes to access different floors of a construction site with different types of materials. The deck can be stacked between floors, to be rolled about as necessary. The loading deck extends 4.5m to 5.25m from the structure. A loading deck can bear loads of 5t when a single person works the deck. Spider cranes and hydraulic cranes are ideally suited for working with loading decks.
An average tower crane lifts material to heights of 70m. The longest crane for hire can reach heights of 18.6m. The spider crane’s small footprint, weight limits, and relatively long boom height suit it well for lifting objects into a loading deck. Also, a tower crane’s massive size renders it not useful in indoor applications.
Depending on the type of work, both tower cranes and mobile cranes are useful. In the case of tight spaces and loading decks, a crane hire of a small to medium-sized crane allows you flexibility in moving material about. Mobile cranes are an indispensable part of construction today.