At the heart of demolition
02 May 2008
It was not long ago that excavators were regarded in some quarters as purely earthmoving machines, but the trend in recent years has seen them used with great effect in demolition applications. Caterpillar, for example, believes that the emergence of excavators as specific demolition tools has come about as a result of the changing nature of the industry. In its view, shorter contract periods, an increased focus on safety and environmental pressure has led to a situation where contractors are, naturally, looking for the safest and most efficient way to demolish buildings, but also with minimum disruption to surrounding areas.
The widespread use of these 'new' demolition machines has led to virtually all the major excavator manufacturers designing and producing models specifically for demolition applications. The differences between standard and subtle to the extreme. As Eddy Powell, director of customer solutions at Volvo Construction Equipment told D&Ri, demolition excavators can be categorised into four types, starting with what Mr Powell calls “standard excavators”.
These machines, he says, are virtually identical to standard earthmoving excavators and are used for secondary demolition jobs such as processing material, sorting and loading. They are fitted with FOPS (Falling Object Protection Systems) and mesh guards fitted to the front windscreen to protect the operator from debris. The cab is also usually fitted with air filtering and conditioning systems, which pressurise it and expel any dust and other airbourne pollutants.
Next are heavy duty excavators, which will be more involved in the actual demolition process and conduct some low level dismantling work. They are, according to Mr Powell, also well suited for secondary applications, but the two pump hydraulic flow offered by most manufacturers means that they can be fitted with grabs and shears to perform dismantling duties. As they are not as powerful as some of their larger relatives, Powell feels that heavy duty excavators are best suited to demolishing smaller buildings or those that have already been reduced in height.
As with the standard models, heavy duty excavators are usually fitted with FOPS and often side impact protection systems to protect the superstructure when slewing.
Full length track guards allow the machines to on uneven surfaces without the risk of track or damage.
Straight boom excavators are, as the name suggests, straight boom machines that have a higher than other machines. A straight boom effectively rules out digging and earthmoving applications, but makes them ideal for primary demolition duties, particularly on high buildings, and tool carrying duties. Again, the machines are modified for the harsh world of demolition through the addition of FOPS and special cab protection measures.
Lastly are the high reach excavators, which are found in the 30 tonne capacity class and above. These machines are used as primary demolition tools and as a result are built to withstand harsh environments. The majority have a folding three section boom, although two section versions are also available.
The operator can lower the engine speed to provide just enough power to operate the hydraulic flow system, unlike earthmoving excavators where operation speed is more important. A camera fitted to the end of the boom that gives the operator a view of the attachment and a spray system to dampen the work area and act as a dust surpressent are common range additions. Additional plates are usually added to the superstructure to withstand the stresses and twisting forces caused by operating attachments at great heights sometimes up to 50 m (160').
So what can the industry expect to see in this sector over the coming year? A wide range of new excavators will be on show at ConExpo in March.
The smallest new Liebherr excavator on show in Las Vegas will be the A900C Litronic wheeled machine. The company says that this machine is an “extensively revised” version of the previous B-series model. A Liebherr D 924 TI-E four cylinder inline diesel engine replaces the previous Deutz model and a new hood has been designed to incorporate the new engine.
The new engine improves the power rating to 88 kW (120 hp). The C series model is also 500 kg (1100 lbs) heavier than its predecessor, which improves both stability and load capacity. The cabin has also been redesigned with a larger windscreen area.
Liebherr has also added the LIKUFIX system as an optional extra on the A900C series. The system is designed to simplify hydraulic tasks by connecting with the excavator's hydraulic circuits and relevant equipment without using flexible hoses. This means that hydraulic attachments can be picked up and set down without the operator having to leave the cabin.
Also on show in Las Vegas will be the massive 125 tonne Liebherr R984C Litronic crawler excavator, which is powered by a water-cooled, six-cylinder Cummins diesel engine with direct fuel injection, twin turbochargers and intercooler that is rated at 504 kW / 685 hp.
Although aimed mainly at mining and quarrying applications, the excavator is well suited to demolition work. It has a maximum reach a height of 16.75 m (55 ft) and can be fitted with attachments such as ripper teeth. A hydraulic quick coupling system is also available for faster and easier attachment changes.
Volvo CE has chosen ConExpo as the platform to launch its largest ever hydraulic excavator. The new 70 tonne machine, which at the time of writing was in its final stages of development and awaiting its final nomenclure, Two models, a standard boom and a mass excavation boom and arm version, will be on display in Las Vegas.
Volvo says that the new machine was designed in close co-operation with customers from around the world and is aimed at demolition, heavy construction, civil engineering, extraction and building.
The excavator will be powered by a Tier 3 Volvo engine using the company's new Advanced Combustion Technology (V-ACT) system. Full production of the excavator will begin during the last quarter of 2005.
The XD (Extra Duty) range of tracked excavators from JCB will be extended at ConExpo with the launch of three models, the 18 tonne JS 200XD, the 20 tonne JS 210 XD and the 23 tonne JS 220 XD. All have been designed specifically for demolition duties and have reinforced dipper and linkages, undercarriage protection and a variety of buffers and protective covers around the machine.
To protect the superstructure and machine rear from damage, extra buffers have been fitted on both sides and around the counterweight. The motors and hoses are protected from debris by heavy duty flush fitted covers and the engine has been fitted with a pre cleaner that prevents pollutants reaching the air filter system. The addition of both these measures, JCB says, minimises maintenance of the machines.
But we do not need to look ahead to the forthcoming ConExpo exhibition for news in the demolition excavator sector, over the past twelve months there has been plenty of activity within the demolition excavator fraternity, with all the major manufacturers adding their product lines.
The majority of these were seen for the first time at the Bauma exhibition in Munich, Germany, last year. O&K, for example, which is part of CNH, completely revamped its range of excavators with nine new machines, ranging from 14 to 48 in capacity tonnes in capacity (pictured on page 12 is the RH5.6). All are equipped with Stage II compliant CNH turbo diesel engines and were fitted with thicker plating in both the main body and undercarriage. Stability, traction and gradeability are improved with the addition of a new chain design Also at Bauma, Case showed its new 56 tonne capacity CX460, (pictured above) in the colours of McCormack Demolition. The machine has a maximum working height of 26 m (85') and maximum forward reach of 14 m (46'). The CX460 is also capable of carrying and operating a 2500 kg (5510 lb) attachment as its maximum working height.
As far as Hyundai is concerned, it was wheeled excavators at the forefront of the company's product development, with the new Robex Dash-7 series. Included in this line up are the 14 tonne R140-7, the 17 tonne R170W-7 (pictured and the 20 tonne R200W 7. The new models are equipped with Stage II compliant engines and electronic engine and hydraulic management systems, features that had already established themselves within Hyundai's popular range of tracked machines.
In the midi excavator sector, Hyundai has launched an improved version of its 5.5 tonne Robex R55-7 for European customers. Improvements in fuel efficiency and exhaust emissions are delivered with the addition of a 53hp (40kW) Yanmar 4-cylinder diesel engine and its management system, which includes a new (patented) foot-operated speed control.
Mini and micro excavators have also continued to evolve and are now also established tools of the demolition trade, often eliminating the need for manual labour in tight, confined spaces.
Bobcat, for example, has developed what it calls 'enhanced' versions of its model 320 and 322 1.6 tonne mini excavators and is claiming improvements in virtually every area. The most visible changes are the newly designed cab and canopy, while a new M-Series Kubota engine increases power.
Also, following on from the introduction of its 430 excavator, Bobcat has extended its range of zero tail swing excavators with the launch of the new 435 model. Together with the 442 excavator, Bobcat now offers a range of three zero tail swing excavators with operating weights from 3.6 to 7.5 tonnes. The 435 will be available in two versions: the 435 FastTrack and the 435 model with conventional drive. A conventional drive version of the 430 will also be launched at ConExpo in March.