Since the dawn of civilisation, our ancestors have used lifting devices, winches and pulleys to transport material from the ground to on high. Some of the earliest examples of the crane date back to the Ancient Greeks with the first undisputed literary evidence for the devices attributed to Aristotlesome 350 years BC. Times have changed since those early rudimentary pulley systems and today there are a plethora of fully mechanised crane designs, typically powered by hydraulics, electricity or internal combustion engines.
Until the turn of the 20th century, cranes were almost always fixed structures, cemented (often literally) in place. Around that time, however, innovative engineers began to design the very first mobile cranes, which were typically steam powered and mounted on to the back of trucks. The invention of the internal combustion engine and appearance of the very first telescopic booms in the 1920s were tremendous steps forward in mobile crane design although it wasn’t until the 1950s and ’60s that the world began to see mobile cranes of a similar sort to the machines so commonly found in construction, transport and manufacturing industries today.
One of the most common forms of mobile crane is the truck-mounted crane. Its anatomy is split into two parts; a body or carrier part that is typically referred to as the lower, and a lifting part, known as the upper. The upper is mounted on a turntable, which itself sits on the lower and is able to rotate and swing. The lifting component is usually operated hydraulically and powered from the same engine that is used to power the truck.
The advantages of these designs are that they are road legal and hence typically remove the need for costly transport arrangements. The largest of these cranes have lifting capacities of around 12 to 13 tons. Whilst expensive, the cost of operating and transporting the machines is far less than the cost of installing a fixed crane on every site a company operates on.
Another popular mobile crane used in construction is the knuckle boom loader. When not in use or when in transit, the lifting component folds up into a tight space able to fit into the trailer of the carrying truck. Unlike the truck-mounted crane, however, the driver must move from the cabin into the truck to operate the lifter.
It is a close cousin to the telescopic handler, which leads on nicely to arguably the most popular of all mobile cranes. The telescopic handler (or telehandler for short) is a hybrid between a forklift truck and a crane. Versatile, powerful and road legal, it is the poster boy of the mobile crane world. Industries including construction, manufacturing, agricultural and transport all utilise these wonderful pieces of kit. Whilst expensive to purchase outright, many utilise telehandler rental firms in order to access the benefits of these cranes at a fraction of the cost.
The rough terrain crane, a close cousin of the truck mounted crane, is designed specifically for accessing off-road sites and tricky landscapes. Not only are the trucks fitted with specially designed tires, outriggers extend from each corner of the truck to stabilise it during operation. As is the case with truck mounted cranes, the rough terrain designs come with four wheel drive. Extra care is also put into designing cabs for maximum visibility.
Crawler cranes are again similar in design, except for the set of tracks mounted upon their under carriage. They are ideal in situations that require lots of moving around site with little set up time, although their tracks mean that they are not road legal and must be transported from site to site. Another advantage of crawler cranes is their extra lifting capacity, which is as great as 3000 tons for top of the range models.
Floating cranes are the aquatic variety of mobile crane and are typically used for building oil rigs, ports and bridges. Mounted on load bearing barges, they are able to move up to 9,000 tons of materials; ideal for huge offshore construction projects.
Finally, and back on land, railcar cranes come mounted to flatbeds with wheels designed for the railways. These are often used freight loading, railway maintenance and recovery operations.
So there you have it, a whistle stop tour of the mobile crane world. How far we have come since the days of Aristotle.