When speaking of tunnelling equipment, many people focus immediately on the major items such as TBMs and drill jumbos which are, compared to conventional construction plant, environmentally "clean".
However, there are many tunnelling projects where the "conventional" construction plant such as loaders, trucks, access equipment and general transport items, which are seen all over Bauma, are in daily heavy use.
Current concerns of plant users and manufacturers, such as fuel consumption, exhaust emissions, noise and heat generation, are frequently accentuated by the tunnelling environment. Some manufacturers with special market positions in underground construc-tion took these concerns on board at an early stage producing, for example, engines with low emissions not requiring exhaust fume "scrubbing". These and other environmental and cost-control developments have been taken up by the rest of the construction industry and its suppliers, and form a particular theme of Bauma 2001.
Manufacturers’ objectives are to use lower energy consumption and reduction of emissions as additional arguments in the battle for market share, so establishing a practical link between environmental protection and sales promotion themes.
Significant recent improvements include those to engines such as refined fuel injection and combustion techniques, lower engine speeds without torque reduction, and more effective cooling systems. Measures such as electronic-hydraulic regulating systems and better fuel-injection control give an optimised combus-tion process on the one hand, with optimum efficiency and ideal emission composition on the other.
Not only engine design is involved, since the make-up of the whole item of plant can affect fuel and environmental efficiency. Bauma organisers predict that designers will focus on individual components as energy consumers including, as well as the engine, the drive system, the hydraulics steering, and coolant and brake systems, to present the whole picture for any given machine.
Engines designed for minimal emissions tend to run at lower speeds, improving the service life of the machine and reducing noise as well as emissions. Such points are often controlled by national and international regulations, but changes in these often have to be anticipated by manufacturers.
Heavy-duty construction designs often incorporate features which are beneficial to the environment and promote long service life. Coolant and oil ducts are integrated into the crankcase to prevent problems with leaky hoses. Instead of vee-belts, toothed gearing, which is relatively maintenance- and backlash-free, can be used in drives.
Hydrostatic drive transmissions are also associated with low engine speeds, minimising fuel consump-tion. Load-sensing controls in hydraulic systems, including steering, have the same effect. They give lower power losses while in neutral and in precision control operations, without unnecessary heating of the hydraulic oil and heat losses.
Plant ventilation systems can help save fuel also, with hydraulically driven, infinitely variable fans using only the power needed by thermal conditions. A mechanically driven, unregulated fan can consume up to 9kW of power on its own. Manufacturers and users of wheel loaders have found regulated fans with separate drives improve noise emission as well as fuel consumption.
As for wheel loaders, distribution of components about the machine for optimum operation and weight distribution can easily improve efficiency. Instead of using artificial ballast, natural weighty compon-ents such as the engine, pump drives, hydraulics and steering pumps, and the hydraulic oil tank, should all be placed near the rear axle, making it possible to reduce the total weight of the machine while counterbalancing the opera-tional load. Light components such as cooling systems can be located near the middle of the machine.
Bauma 2001 is presenting itself as a discussion forum for operators and manufacturers to make progress in reducing noise, water and air pollution, avoiding machine vibra-tions, and eliminating waste.
