A busy commuter road is to be re-routed and widened to create more lanes of traffic. A number of different surfaces need to be torn up and replaced; asphalt, granite and cement are all cracked due to wear and age. If the operator applies too much force, the ground next to the road could give way and damage bridges, pylons and buildings. One false move could mean a bad day for unsuspecting motorists and locals.
As an experienced breaker operator knows, the right amount of power is paramount in every situation. Too much force could mean not only higher running costs but permanent damage to the breaker. But if too little power is applied, the rock will not break. Materials that are hit hard act like an elastic spring so the energy could be returned to the breaker or, in the worst case scenario, to the carrier.
Roadwork, quarrying, demolition and construction groundwork all require specific breaker sizes and blow rates. The choice of breaker is a complicated task, as the machines are heavy and unwieldy, even in the smaller ranges. A way of working with different types of rock in the same location without the need to change breakers would make all the difference.
With these concerns in mind, Sandvik has devised a large range model that is, in many ways, several breakers in one.
A simple switch allows the Sandvik BR4099 to be purpose-matched to different jobs and rock types. The operator can choose between two working modes: a high energy mode for optimum breaking power in hard materials and applications such as granite and heavy demolition, and a high frequency mode, which is more productive when breaking up softer materials such as limestone.
?When working on different materials and with different applications, adjustability is a big plus,? says Sandvik?s market offering manager Jukka Kyt?m?ki. ?If you work on hard rock, the power is more crucial than the frequency. On softer material it?s the reverse. Adaptability makes this a far more versatile tool with more capacity for production.?
As well as the pioneering working mode switch, this model benefits from other features, such as improved hydraulic efficiency, so as to deliver massive impact energy and exceptional power-to-weight ratio. This feature, according to lead designer Ossi Kahra means ?better manageability and higher productivity? because the breaker is dimensioned hydraulically and mechanically. It can be used thanks to its high back pressure allowance.
The BR4099 breaker is the result of research and feedback collected by different departments at Sandvik?s Lahti offices in Finland.
?This model was developed after feedback from our customers, that they needed a reliable breaker with lower operating costs but without compromising productivity,? Jukka Kyt?m?ki says. ?It was launched at Bauma 2010, and initial feedback was positive. Visitors were interested in the new operating principle, where the operator can choose between blow rates. The best feedback, however, came from customers who worked with the test units. They all placed orders.?
These units, launched in Vaasa, on Finland?s west coast, in February 2010, were unveiled to a select group of mining and construction company representatives.
?The range of new features and operability options is a response to their needs and concerns over the years in terms of downtime, cost-efficiency and durability,? Jukka Kyt?m?ki says. ?We could also show how it excels in the most demanding situations.?
A company that tested the new breaker is Max Wild GmbH from Berkheim, Germany, which ordered some for an important demolition project in Haseltalbr?cke. The site is a ?40 million development to widen the A3 motorway bridge between Frankfurt and Nuremberg from six lanes to eight. The breakers were successfully used to smash up the 65m high pillars supporting the bridge to make way for a new support structure.
Weighing 3380kg, the BR4099 is suitable for all hydraulic excavators in the 35 tonne to 60 tonne weight class. With an operating principle that offers variable stroke length, blow energy and a selectable idle blow protector, it also reduces running costs. Vibration dampened tie rods (VIDAT) improve reliability and minimise downtime by restricting the impact and wear on both the breaker and the carrier.
Hydraulic breakers tackle some of the toughest tasks in the construction and demolition industry, so everyday wear and tear cannot be completely avoided. With so many steel parts working alongside each other and so much heat generated, greasing is a huge maintenance priority. This is why Sandvik opted to extend the working life of both breakers as much as possible by offering three options to deliver optimum levels of lubrication for greater wear protection and a longer operating life. ?The greater efficiency of this model brings lower fuel consumption and lower operating costs, compared with similar-sized breakers in the market,? Ossi Kahra says.
Jukko Kyt?m?ki adds: ?While we are always concerned with being competitive in terms of both price and quality, what is even more important here is the lifetime cost and payback period. In these terms, the BR4099 is going to be very economical to use.?
Movements like a human limb
As anyone who has seen hydraulic excavators in action knows, the movements of the working equipment are like those of a human limb. The boom portion of the equipment acts like the upper portion of an arm and the breaker like a fist. As power is nothing without control, the BR4099?s operating principle features the pioneering constant blow energy principle, which means that the breaker?s full power is available within the whole flow range. Operating pressure in the breaker remains stable, giving it full power. The breakers also allow high back pressures, so combined with the wide flow range, it is easy to fit them onto different carriers with a variety of flows and still supply full power.
The idle blow protection protects the breaker against idle hits. If the piston is not in firm contact with the tool, idle blow protection prevents the piston from moving. Sandvik has also fitted a hydraulic brake on the cylinder, which keeps the piston from hitting the cylinder end even if the idle blow protection is not on.
Source: Sandvik Mining & Construction