1.1 – What Is a Crane?
The Oxford Dictionary defines a crane as “A large, tall machine used for moving heavy objects by suspending them from a projecting arm or beam” (Oxford Dictionaries, n.d.). Today they are a common sight on building sites around New Zealand. They come in many different forms that have been adapted to suit different applications.
1.2 – What are the main (common) parts of a crane?
Cranes vary in size, shape & specialty but they are all based on the same principal. As such, there are some parts that are common between all cranes that have been listed below. These elements are also shown in Figure 1.
Boom (jib)– This is the arm that does all the lifting.
Hook Block – A pulley block with a hook. This is where …show more content…
Slew ring (turntable) – The gears which a crane uses to rotate. This is a fixed location usually directly under the operators cab.
Counterweights – A set of large weights positioned in line with the boom but located on the opposite side of the slew ring.
Figure 1: Anatomy of a Tower Crane (Wick, 2010)
2. How Cranes Work
A cranes purpose is to pick up and move objects in a horizontal and/or vertical direction before placing them down again. The size of the load a crane can lift is based on its weight rating. This varies greatly between cranes and often two cranes with the same or similar ratings will be required on a large building site to ensure all lifts can be made.
2.1 Load Charts & Lifting Capacities
The capacities listed in a cranes load chart are not the actual loads that can be lifted on the …show more content…
Types of Cranes
Today there are many different types of cranes that have been designed to perform many different tasks. The most commonly seen cranes on New Zealand building sites are tower cranes, crawler cranes & truck mounted cranes.
4.1 Tower Cranes
Tower cranes are almost always the largest on a site and consist of a foundation pad (or base) that has been engineer specifically for that crane on that particular site. The mast which attaches to the pad & gives the crane its height. At the top of the mast a slewing unit is attached. This unit contains all the gearing & the motor that allows the crane to.
On top of the slewing unit sits the horizontal jib. This is the large beam that projects out from the centre of the mast & all lifting is done from this. There is also a set of trolleys with pulleys & a hook attached. The load is attached to the hook & the trolleys move along the jib to allow the loads to be moved closer or further away from the mast depending on their final