Earthmoving machines the backbone of construction

Earthmoving machines remain the backbone of construction operations - writes Mike Woof

ADTs, excavators and wheeled loaders play pivotal roles in most construction jobs with the earthmoving stage providing a key component of most projects. This year has seen the introduction of several new and upgraded ADTs, with the promise of more to come in 2011 when the Tier 4 Interim/Stage IIIB exhaust emission regulations come into force for North America and Europe. These will require new low emission engine technology featuring exhaust after-treatment and those manufacturers that have not released new models during 2010 will certainly do so in 2011 as a result.

1240 Bell continues to add updates and improvements to its ADT line-up, with several upgrades fitted to what is now the MK VI version of its D series. A number of these features were first introduced on the top of the range B50D but have now been made available across the line-up. The sophisticated i-Tip system is now installed as well as front suspension, an inclinometer and an onboard weighing system, all fitted as standard across the range. The i-Tip system helps reduce wear and tear on the machine as well as boosting working safety. This provides a soft tip/return for the body that cuts shock loads to the structure and hydraulics while the system can also be set to help reduce carry-back and debris. Another feature of i-Tip is the restrictor that prevents the truck from accelerating beyond a set point while the dumpbody is raised, increasing stability and safety.

According to Josh Foster, sales & marketing manager at Bell Equipment UK, the firm has opted to add improvements to its ADTs on an incremental basis rather than by introducing a new generation every few years. "We've gone to making small evolutionary changes," he said. "These are small but regular enhancements that over time will complete the range change. When we went from C-D, that was a revolutionary change."

Foster explained that introducing such major product updates at one time can lead to unexpected issues, while the incremental process offers benefits in terms of reliability. He said, "In the long term it does improve our warranty claims as well."

The inclinometer measures the pitch and roll of the truck and this can be set to provide a rapid warning. The system plays an important role and Foster said, "If the rear end goes over it can damage the body heating kit."

Successive upgrades to the electronics are playing an important role in the D series MK VI models, with the systems having been designed to be future-proof. An automotive type, CANbus electrical system allows Bell to run sophisticated electronics and add features while using a comparatively simple wiring harness that is easy to maintain and Foster said, "What we've tried to do is simplify the electrical system."

In previous generation ADTs from Bell the electrics were routed through the roof of the cab but he said that a study showed electrical problems tended to be related to the work environment such as from dirt or moisture ingress - with the actual electrical component design life exceeding that of the truck. As a result the new machines now have most electrical components gel-sealed, "...with only the relay switches and fuses kept behind and access panel," said Foster.

One innovative new electronic control feature is the system that optimises gear changes to minimise cycle times. This system takes note of whether the truck is running laden or unladen as it is linked to the payload indicator and adjusts gearchange times and settings automatically so suit, rather than changing at pre-set engine speeds. The control system offers numerous other features too and Foster gave an example, "If the machine is on a hill, it won't release the handbrake until there is enough engine power, so there's no roll-back. This works automatically and the driver won't even know the machine is doing it."

He added, "This software platform leaves the chance for further intelligence down the line. If you think about it, we could take the retardation out of the cab for example. What we want are clever trucks and the machine that knows what to do can save a lot of time on-site."

Looking ahead he said that the main feature of the MK VII models will be with the fitting of Tier 4 Interim/Stage IIIB compliant engines. Foster added, "We're ahead of the curve in a lot of areas. Our comfort ride feature is a practical solution at a lower cost than some competing systems."

2415 Hydrema is hoping to boost sales for its niche market compact ADTs, the 922 and 912, with improved models now on the market. The standard 922D features a 20tonne capacity and weighs in at 15.8tonnes unladen, with drive to all six wheels. Sales director for Hydrema UK is Tim Wadsworth and he said, "We've given it a facelift and a new cab. It's the D-series cab from the 912. We added a hydraulic retarder that works on the rear axle in addition to the exhaust retarder."

Featuring twin axles, the 922D uses a pivoting bogie system similar to that seen on some graders (as well as the larger 695 Doosan 1239 Moxy ADTs) at the rear to provide four wheel drive at the rear. This design offers high performance in undulating terrain as the bogies have a large pivot angle and also allow the tyre profiles to remain at optimum angles to the ground. Because the machine has a pivot system rather than a turning ring as used on other ADTs, Wadsworth claims this provides an anti-roll function and boosts stability compared with competing units. The truck comes with 800mm wide tyres as standard for markets such as the UK to suit low ground pressure applications. However, Wadsworth said, "There is a narrow tyre option for road use."

Wadsworth said that the skid unit is similar to that on the previous machine and retains proven features such as the 196 Cummins diesel, 2304 ZF transmission and wet plate disc braking system on all six wheels. The 6.7litre QSB diesel delivers 194kW and meets the Tier 3/Stage IIIA emissions legislation and drives through a ZF6WG210 Ergopower transmission with six forward and three reverse speeds and allowing a top speed of 50km/h. Wadsworth said, "The power to weight ratio is the best in class."

A centre differential (with a 100% lock capability) is located in the transmission's output shaft and equalises the speed between front and rear axles. With its light weight and efficient driveline, the machine uses 11litres of fuel/hour according to Hydrema's performance tests and Wadsworth commented, "It's very economical on fuel."

The truck also has a hydraulic tailgate and electronically-controlled body opening. Wadsworth said, "It tips in 7.5 seconds and takes 5.5 seconds to lower the body. It is fast because it powers up and down and the ram is inside the chassis rails for protection."

The compact 10tonne capacity 912D weighs in at 17tonnes unladen, is powered by a 299 Perkins diesel rated at 96kW and has wet plate disc brakes on all four wheels. Hydrema is also offering special versions of its 912D, with the 912DS featuring front axle suspension for greater driver comfort and the 912HM (high mobility) suiting low ground pressure applications. The 912DS is fitted with hydraulic accumulator suspension but looks outwardly similar to the standard 912D, however the 912HM is discernible by its larger tyres. Wadsworth said, "We changed the axles so it'll go up to an 800mm wide tyre." He explained that the 912HM offers a similar low ground pressure performance to some of the track options available for ADTs. And this is also at a significantly lower purchase cost and with far more economical running costs, due to the greater wear life of the tyres over the rubber tracks. The 912D, 912DS and 912HM models all come with the option of standard or multi-tip bodies.

718 Liebherr recently lifted the covers on its TA230 ADT, a machine with a 30tonne payload. Like many Liebherr machines the TA230 is designed to be rugged and durable, while it is also fairly compact given its 30tonne payload and is similarly sized to many rival 25tonners. It features a 19m3 dump body and Liebherr will be offering ADTs with capacities of 40tonnes and 50tonnes shortly that will share many of the same design features. Liebherr has been developing its ADT range for several years and worked on prototypes with innovative hydrostatic drives but opted in the end to offer a conventional driveline, largely on grounds of cost.

Liebherr has been keen to offer a highly productive machine and the TA230 is said to cycle faster than its leading competitors due to a high power to weight ratio. A 270kW, Tier 3 compliant Liebherr diesel developed in partnership with MAN powers the TA230 and this allows a top travel speed of 57km/h, which is notably quicker than much of the competition. Even reversing speeds are high with a maximum 16km/h while the truck has quick tipping times of just 10 seconds. Low emission solutions to meet the coming Tier 4 interim and Tier 4 final regulations will be ready when required in 2011 and 2014 respectively, again developed in partnership with MAN and based on its proven on-road technology. The truck has a comprehensive retardation package and features oil-cooled, wet plate disc brakes fitted to the front and centre axles.

To further boost productivity the high comfort, high visibility cab is said to reduce driver fatigue over a full working shift, further aided by an effective front suspension system. The machine is said to be easy to operate with an automatic transmission while effective retarder controls ensure the TA230 can be driven safely on steep descents. The operator benefits from a diagnostics system that displays machine condition and provides alert warnings when required. Other features include Liebber electronics, rugged shock absorber units and durable, long stroke Liebherr cylinders for the dumpbody.

Liebherr is keen to raise market awareness as to the benefits of its TA230 and is putting some of the first units into its rental fleet. As the Liebherr ADT range is introduced to the rental fleet the existing arrangement with Bell over hire of its machines will however come to an end.

1222 Terex's new TA300 articulated truck replaces the TA30 model launched in 2002 and adds to the line-up of new ADT models from the firm. This 27tonne payload truck features a sophisticated fully independent, double wishbone front suspension system, unlike the strut systems used by many rival firms. Terex introduced the TA400, TA350 and TA250 earlier, replacing the previous TA40, TA35 and TA25 respectively and this latest machine shares many of the same features at its revamped siblings.

The double wishbone front suspension package is a key performance feature of the TA30 as it provides the driver with a smoother ride on rough ground. This can directly help boost cycle times by allowing higher travel speeds, and indirectly by reducing driver fatigue throughout the working shift. The system also helps reduce shock loads to the machine and cuts wear and tear, while providing a positive steering response for greater precision on undulating terrain.

Power for the TA300 comes from a Cummins diesel delivering 287kW and which meets the Tier 3 emission regulations. A further upgrade of the Terex ADTs will be available with the new Tier 4 interim compliant diesels that Cummins has already unveiled, to meet the new regulations coming in 2011. Braking for the TA300 is by wet plate disc brakes to all six wheels, with a 1662 Jacobs type retarder as standard and the option of hydraulic transmissions retardation also available. An array of options is available for the TA300 and its siblings to suit different applications including body liner kits, tailgates and side extensions for use when carrying lower density materials. The standard capacity in the body is 17.5m3 while its payload is 28tonnes but these vary depending on which options are selected and the machine is said to deliver a high productivity for its size class. By comparison Terex's top of the line TA400 has a capacity of 23.3m3 and offers a travel speed of 60km/h. As with its siblings the TA300 has a new high comfort, high visibility cab that also offers lower noise and an improved mirror layout.