High performance, high mobility of wheeled pavers

The high mobility afforded by wheeled pavers is favoured in some markets - Mike Woof reports

New generation wheeled pavers aimed at use in territories such as the UK, Italy, South Africa and Southern Germany are now coming to market. Pavers in these countries are often expected to be driven from one part of a site to another or for short distances, which is why the additional mobility of the wheeled machine is preferred in many instances over similarly-sized tracked models. This preference for wheeled units comes in spite of the greater stability offered by tracked machines. 172 Bomag, 178 Caterpillar and 206 Dynapac are all offering new models for this market, while 6791 Ammann has revamped the 2525 Antec models it bought recently.

What is worth noting too is the Italian influence in these wheeled paving machines. The 172 Bomag machines are now built in Germany but have been developed in Italy by sister firm 273 Marini within the 217 Fayat Group. Caterpillar's European built pavers are manufactured in the Minerbio facility close to Bologna, acquired when the firm bought the Bitelli business. And the Antec line that Ammann bought and re-engineered was developed originally by a team who had previously worked at Bitelli. Ammann, BOMAG and Caterpillar all now offer wheeled paving machines that are considerably improved from the designs they were developed from, but these units share Italian origins. By comparison, Europe's other three major paver brands, Dynapac, 1194 Vögele and 2394 Volvo, are all based on German technology.

Although Swiss firm Ammann has long been a player in the asphalt equipment market with its batching plants and compactors, the firm has only recently entered the paver segment following its buyout of the Italian Antec business.

The company has totally revamped the AFW150, 270, 350 and 50 models, giving these improved drive and control features, which make them easier to use and more progressive in operation.
Some of the hydraulic components now used in the pavers have already been proven in Ammann's compaction range. The AFW270, 350 and 500 models are offered with a choice of four wheel drive and six wheel drive. All of the pavers in the Ammann range can be fitted with a vibratory screed or a tamper/vibratory screed, with both electric and gas heating options. The AFW270 competes in the 5tonne paver class, with extending screed widths of 1.4-3.33m. The AFW350 is in the 7.5tonne class and has paving widths from 1.83-4.5m, while the AFW500 is in the 15tonne class, with paving widths from 2.55-6.5m.

BOMAG continues to develop its paver range and the new BF800 model shares features with the recently launched BF600 and BF300 models.

This 20tonne machine is offered with 6x6 drive as standard and an electric screed as standard, with paving widths of 2.5-5m. The cast electric heating elements are said to provide an even distribution of heat, reducing warm-up times. The BF800 has a high-capacity hopper and wide bin width for efficient loading. Control is provided on both sides from side-mounted operator stations. A new diagnostics system is fitted that can detect and highlight problems with material flow. The machine comes with BOMAG's ECOMODE management system, with four operating modes to help optimise performance and reduce fuel...
Caterpillar says that its new AP500E asphalt paver provides high performance for its size class. The machine is said to have high mobility and good visibility, with power from an emissions compliant C4.4 diesel delivering 106kW. The AP500E is versatile and offers quick set-up times, while its compact and lightweight design allows it to be transported quickly between sites. The machine weighs in at just over 16tonnes when fitted with the new AS4252C electric heat screed. The machine has a wheeled undercarriage, dual operating stations, a high capacity cooling system, belt-driven generator and a novel material handling system with independent conveyor and auger controls. The dual swing-out stations, tilting consoles and low profile design of the cooling system provide good forward visibility for loading and monitoring of the mix in the hopper. Because the operator stations can be swung out over the side of the frame, this allows better joint-matching and also improves rearward visibility. A sophisticated advisor monitoring system is fitted to the left operating station, which features tools such as a project planning calculator, a start-up checklist and data on engine operating conditions. The system also lists fault codes for machine functions, making service, maintenance and repair tasks easier.

The machine runs on non-directional radial drive tyres with a large ground contact area for flotation, stability and tractive effort. A position sensor located in the left steering cylinder helps maintain consistent travel speeds during turns by adjusting the drive speed of the propel motors according to the steering angle of the front wheels. This provides a better mat quality and also reduces wear for the drive system. The machine also has a front wheel assist option that delivers power to the front bogie wheels for added traction when pushing trucks or working on soft base. Another option is an all-wheel drive system to maximise tractive effort. The machine has automatic speed control and three propel/steering modes. The travel mode allows speeds of up to 16km/h for mobility, while the pave also sets up mix delivery system and a manoeuvre mode allows 0.75m inside turning radius for mobility in tight quarters.
The firm says that the machine's material handling system is highly advanced with automated controls to help reduce material segregation and maximise mat quality. The left and right conveyors and left and right augers are controlled independently to further optimise mix flow when increasing or decreasing paving widths. Ratio control dials and sensors allow the augers and conveyors to run faster or slower when changing paving widths, keeping the head of material at the set level.

A 25kW generator provides power for the electric screed heat, auxiliary lights and job site tools. The 4kW auxiliary power panel is equipped with two, 220V receptacles for job site lighting and other work tools. The AS4252C screed features variable frequency tamper and vibrators...

 The new AP500E paver from Caterpillar offers high mobility for working on sites where space is restricted

The hydraulics and electrics have been totally upgraded for the new Dynapac SD2500W and SD2500WS pavers

 ...and fast warm-up times. The AS4252C is a double width hydraulic power extendible asphalt screed with a standard paving range from 2.55- 5m and a maximum paving width of 7m with bolt-on mechanical extensions. The extenders have 330mm wide screed plates, allowing it to work close to obstacles.
The new Dynapac SD2500W and SD2500WS will have to meet the Tier 4 Interim emission requirements so they have been completely redesigned. Paver specialist Sonja Böcker said "We took the opportunity to make everything new." Twin seats are fitted that can be slid over the side by 500mm or turned for better visibility of the screed and other operations, while the new dashboard can be slid from one side of the cab to the other. The canopy versions of these machines are standard models, although Dynapac can supply side screens and even a fully-enclosed cab if requested. The screed controls are integrated into a single panel and the machine is linked to a 1228 MOBA paver control as standard, with the option of 342 Topcon or 2122 Trimble 3D paving guidance technologies also offered.

The 2500W offers paving widths of up to 7.3m when fitted with extension boxes and features the firm's V5000 screed, while the six-wheeldrive DS2500WS is fitted with the V6000 screed and can pave widths of up to 9m using extensions. Böcker added, "You can choose between gas or electric heating." This redesigned machine is also said to be more fuel-efficient than previous machines from Dynapac, although Böcker said, "The main fuel saving comes from the more efficient hydraulics." Because the paver operates more efficiently due to the revised hydraulics, Dynapac has also been able to use a slightly smaller engine as the previous model had a 153kW power unit. The 129kW QSB6.7 196 Cummins diesel slots into the tractor chassis and although visibility over the engine cover is good, plenty of space has also been left for the full emissions package that will be required to meet the Tier 4 Final legislation.

Load-sensing front wheel drive is fitted and this delivers the drive proportionally in relation with the load in the hopper.

The system reduces the tractive effort to the front wheels as the hopper load decreases, so that the risk of wheelspin is reduced and this is said to be more effective than the anti-spin system fitted previously. Hydrostatic braking provides effective speed control and reduces wear and tear, with the disc brakes only required for parking. Other features of the machine include wider profile tyres that optimise traction and a fuel tank that is in two pieces to allow space for the materials conveyor and which has a capacity of 350litres.