Equipment attachments: Tools of the trade
By Chris Sleight09 May 2008
Equipment attachments are the tools that allow machines like excavators and loaders to carry out their work. The simplest and most common types are attachments like buckets and pallet forks, and these of course come in all sorts of shapes and sizes. Chris Sleight reports.
With the increasing range of attachments available today - from simple buckets to complex hydraulic tools - machines can replace manual labour in more and more situations, leading to greater productivity. This should add up to construction projects getting completed faster and with greater efficiency.
One of the key tools to achieve this, and an attachment in its own right, is the quick hitch. Back in the bad old days, tools were pinned directly onto machines and changing them meant knocking the pins out with a sledgehammer - time consuming and strenuous work.
Today though there are plenty of quick hitches on the market. These latching systems allow tools to be changed without the operator getting out of the cab in many cases, and certainly without having to start swinging a sledgehammer around.
The most sophisticated markets in Europe, if not the world, as far as quick hitches are concerned are the Nordic countries. This is due to the efforts of Swedish manufacturers like Engcon, Indexator and Steelwrist, which have pushed the concept of excavator quick hitches that both tilt and rotate.
Instead of moving in just one axis on the bucket tilt cylinder, the added flexibility of a hitch that tilts up to 45° each way and can rotate continuously gives operators a huge degree of freedom when using their machines. The added movement means even using a straightforward bucket, material can be placed with great care and precision in all sorts of awkward places.
It may not sound like much, but if an excavator can do a task in a few seconds that it would otherwise take a few workers with wheelbarrows and shovels a several minutes to do, the savings really start to add up.
According Steelwrist, the use of these ‘tiltrotators' makes work on site +25% to +35% faster. In fact, so effective have these devices proven that they are now a ‘must' in the home market.
"A few years ago you might have got an extra € 5 per hour if you rented out a machine with a tiltrotator on it. Today you couldn't get a job without one," said Steelwrist president & CEO Stefan Stockhaus. "Market penetration in Sweden is 95%," he added.
This statement applies to carriers from about 1,5 tonnes to 30 tonnes. Above 30 tonnes, machines tend to be used for mass excavation, so the advantages of a tiltrotator are of less benefit. Lighter machines however, particularly mid-sized excavators and backhoe loaders, often end up in multi-purpose roles.
One apparent disadvantage of tiltrotators is the additional length on the end of an excavator's stick will reduce breakout force. This is true - it's a simple matter of leverage and moments - but in markets where tiltrotators have been adopted, it is not a major problem.
"There is a theoretical argument about breakout force, but in reality it doesn't matter. At the end of the day its all about productivity," said Mr Stockhaus.
At the machine end, tiltrotators can either be attached with a quick-hitch or pinned directly on. In the first case, it is the work of a few seconds to remove the tiltrotator and pick up a bucket directly if heavy excavation calls.
A tiltrotator also adds cost of course, but according to Mr Stockhaus, the additional +7% or +8% on the price of the carrier is a small price to pay for +25% to +35% more productivity.
Fitting a tiltrotator requires changes to the excavator's controls and wiring harness, and Steelwrist sells its units as a complete package. The biggest change an operator would notice is the replacement of standard joysticks with new units including a roller or rocker switch to control the attachment.
Although this sounds a little involved, Steelwrist's chief technology officer Markus Nilsson told CE, "It usually takes less than a day to install everything."
He added that in Sweden, some excavator manufacturers, including Caterpillar, now supply their machines with these more sophisticated joysticks straight from the factory.
But while tiltrotators are boosting productivity in Scandinavia, a very different type of quick hitch has become a major source of concern in the UK. Last year there were four deaths on UK construction sites due to the misuse of so-called ‘semi-automatic' quick hitches.
These units, which are straightforward mounting brackets without any tilt or rotation features, can pick-up attachments but do not lock them securely in place until a pin is inserted by hand. They differ from other quick hitches on the market, which are either manual - both picking-up and locking the attachment requires a manual intervention from a worker - or fully automatic, where the device picks up and locks onto an attachment at the touch of an in-cab button.
The danger with semi-automatic hitches is that an operator might pick up a tool, but not put the locking pin in place. It may have got lost, or the bad weather might discourage the operator from getting out of the cab, for example. This seems to have been what happened in the four fatal accidents in the UK in 2007. Without the locking pin in place, buckets fell off the excavators that were using them, killing workers underneath.
As an interim measure the UK's Health & Safety Executive (HSE) has published a short document called ‘Safe use of quick hitch devices on excavators', highlighting the issues with semi-automatic hitches. The document also offers some advice to fleet owners, such as painting the pin and its insertion hole to remind operators to fit it, or using simple retaining systems to stop pins getting lost. The document is available at www.hse.gov.uk
In the longer term however, it looks like semi-automatic quick hitches will become a thing of the past. According to Malcolm Kent, technical consultant to the Construction Equipment Association (CEA), this problem falls under clauses covering ‘foreseeable misuse' under the Machinery Directive, the central piece of European legislation covering construction equipment.
"People get sloppy frankly. But in practice, if it's pouring down with rain, on a muddy site, people are not going to get out of the cab to put a pin in," said Mr Kent.
The foreseeable misuse provisions of the Directive cover such situations, where products are not inherently dangerous but pose a risk if they used incorrectly, and the reason for their misuse is understandable.
According to Mr Kent, with safer products on the market in the form of manual and fully automatic quick hitches, there is now industry consensus in the UK to move away from semi-automatic devices. This will be done by re-writing the section of EN 474 part 1 - the technical standard that supports the Machinery Directive - that refers to quick couplers (‘attachment brackets' in the standard's language).
The standard will come into force with the updated Machinery Directive at the end of 2009. While it will not ban semi-automatic quick couplers directly, when the standard is re-written manufacturers will not be able to claim conformity with the Directive.
"By the end of 2009 the standard will preclude the sale of semi-automatic couplers. Once the standard is updated people will stop selling them," said Mr Kent.
While this is what the UK industry - including quick hitch manufacturers - is calling for, such action would of course impact on the entire European market. However, Mr Kent said this was not expected to be a problem.
"There hasn't been any opposition anywhere else in Europe. As we understand it, semi-automatic quick hitches are not so popular in other parts of Europe, although there have been some verbal reports of accidents," he said.
Across Europe the versatility a quick coupler brings, means they are often a key part of the shopping list when a new machine is bought. Jeff Gilbert, Volvo Construction Equipment's global marketing manager for attachments told CE, "Couplers - both mechanical and automatic - are very popular with excavators and backhoes. About 30% of machines are sold with a coupler these days."
Beyond the coupler itself, there is a massive choice of tools on the market, and many are sold as part of a new machine package. Freddy Remory, Bobcat Europe's product manager for attachments said, "We sell 1,5 to two hydraulic attachments with each machine."
When specifying attachments, buyers have the choice of either opting for a tool from the carrier machine's manufacturer, or going to a third party supplier. In the past third party players dominated the market, but these days many of the major excavator and loader manufacturers have their own lines of tools.
They may not make every attachment themselves. Hydraulic breakers for example still tend to be the built by specialist companies. But more and more these specialists are supplying ‘branded' breakers to major players like Volvo and Bobcat.
This of course makes good business sense for the manufacturers, but they also argue that supplying a complete package of carrier and attachments means a better solution for the customer.
"Customers like to buy everything from one shop. There is a lot of trust. The one-stop-shop is important, but so is the trust - customers know that we've tested the attachment and we're going to stand behind it with warranties and it is matched to the machine," said Mr Gilbert.
He continued, "We run attachments through a validation process to make sure the attachment is right, for the machine. We have no problem standing behind and attachment as long as it's sold onto the right piece of equipment."
Matching the right attachment to the right machine is an important issue, especially with hydraulic tools, where the oil flow the machine can provide has to be a good match for the tool's design.
As Mr Gilbert explained, if there is a big mismatch between the two, trouble will not be far away. "You're going to destroy either the attachment or the carrier. You can get by a little bit, but you're going to cause undue stress on the machine if the tool is too big, and if its too small, you're going to destroy the attachment."
This of course is another argument for going to a single supplier for carriers and attachments. Mr Remory said, "We state very clearly which attachments can be mounted on which machines. We don't run into any problems."
He added, "There are lots of competitor attachments that fit Bobcat machines. They're not approved and with more complicated attachments it can be difficult to make them work."
Bobcat for one is building on the idea of well-matched carriers and tools, with even greater levels of sophistication. "Our new soil conditioner for example has an attachment control device (ACD). When you connect it to the machine, the carrier knows what type of attachment it is and knows whether it should be high or low flow. It's a plug & play system," said Mr Remory.
Of course this is not to say that buying a third party attachment is a bad idea. Look at the hydraulic breaker sector, where more than 50 specialist manufacturers serve Europe. This provides more choice than a ‘one-stop-shop', and gives buyers more scope for negotiation than going to a single supplier.
The point to remember is that in taking this approach, the onus is on the equipment owner to ensure that attachments and carriers are well matched. It's not rocket science. Even the most basic attachment spec sheet will specify the class of carrier and required hydraulic flow, and these have to be matched against the intended carrier.
So getting the right combination of carrier, coupler and tool is essential for equipment owners, and of course the market is always moving forward. The key aim for manufacturers is to provide tools that are as productive, trouble-free and easy to service and maintain as possible.
For example, Atlas Copco's hydraulic compactors now come with the company's ‘PermanentLube' system, which keeps the attachment lubricated at all times. "With this feature all of the compactors of this range require practically no maintenance," said Atlas Copco Construction Tools' technical specialist, Roland Stiller.
In addition, there is the option of continuous 360° rotation on the HC 308 upwards, which makes them much easier to use in tight spaces such as trenches.
Besides boosting productivity, improving safety and keeping dust, noise and vibration down are important issues with attachments - as they are in virtually every aspect of the construction industry. Again this is an area where excavator-mounted compactors score above hand-operated plates. The operator is safely out of the work area in a cab that protects against noise, dust and vibration. In addition, running a compactor hydraulically instead of with its own motor means less noise in the environment.
Flexibility is another important area for attachments, and one that is best illustrated by multi-processors used in the demolition industry. Cutting or crushing different types of material requires different blades and jaws. Rather than force contractors to buy a different tool for each type of material they are likely to encounter, it is now common to see multi-purpose cutters with inter-changeable jaws.
But perhaps the most striking example of flexibility in attachments over recent years is illustrated by Montabert's Silver Clip range. When switching between bucket and breaker work, the bucket can be mounted directly on the end of the breaker, rather than having to remove the tool and then pick up the bucket. Another option is to fit a compaction plate on the end of the breaker tool and use the hammer's reciprocating action to consolidate soils.
Another trend in the attachments sector is for bigger and bigger tools. Last year's Bauma exhibition saw Atlas Copco unveil its HB 10000 hydraulic breaker, which weighs in at a massive 10 tonnes. One of these units has since been used for rock excavation on a railway expansion project near Oslo (see p.XX).
This year saw Indeco unveil and even heavier model in the shape of the 11 tonne HP 18000, now the biggest breaker in the world. The unit unveiled by the company at last Month's ConExpo exhibition in Las Vegas, US has since been put to work contractor Urban Foundations Engineering on a foundation excavation scheme in New York.
These are just a few of the examples of developments in the attachments sector. It is a massive market with hundreds of active companies working on different areas and applications.
However, the aims are strikingly similar - to increase productivity and reduce manual labour. As the example of tiltrotators illustrates, merely being able to move an excavator bucket more flexibly can have a striking impact when on efficiency.