Despite comprehensive Euromot 4/Tier 4f revisions, TADANO remains the only manufacturer to hold fast to a two-engine strategy from its 70-ton class upwards.

Adapting an engine to a new exhaust standard is famously associated with considerable design and construction expense for crane manufacturers. This is essentially because, aside from the new technology that has to be integrated into cranes, the new engines are usually bigger and heavier than their predecessors. As a result, other components have to be changed in terms of their shape, size, and/or placement in order to make space for the new engine – or engines. “This domino effect goes on and on, and in the end when you revise an engine you have to look at the whole crane,” says Dr. Bernward Welschof, Head of Research and Development at TADANO FAUN.

All-terrain crane manufacturers have adopted different strategies in order to minimize the time and expense of adapting to the new Euromot 4/Tier 4f exhaust standard. One possible strategy is to reduce the number of engines in a crane. That is why we have recently seen more and more manufacturers bringing single-engine cranes onto the market so that they can comply quicker and more efficiently to current and future legal regulations, even in crane categories that used to be the exclusive domain of two-engine designs. TADANO also considered this way of doing things: “I can remember as if it were only yesterday,” says Thomas Schramm, Head of Sales and Marketing at German subsidiary TADANO FAUN in Lauf an der Pegnitz, Germany. “We discussed long and hard what the right way might be for us, and we weighed up the pros and cons of single- and double-engine strategies. On the one hand, one-engine solutions offer shorter development times and reduce development costs. On the other hand, two-engine concepts offer very clear advantages in terms of crane operation and operating costs. Our engineers believe that there is more benefit for customers in a two-engine solution because it saves fuel when operating the crane, and there is less wear on each engine.”

In the end, TADANO did opt for the two-engine strategy, and therefore for more customer benefit, and is continuing to pursue that approach, as so impressively demonstrated at the TADANO Crane Day on June 12/13, 2015, on TADANO FAUN GmbH’s premises. “We didn’t allow the immense time and expense associated with the Euromot 4/Tier 4f revisions to divert us from our approach because we wanted to offer our customers what is for them the most economical solution – even if, metaphorically speaking, it hurts us a little,” explains Dr. Bernward Welschof. Guests at the TADANO Crane Day were able to see for themselves how all-terrain cranes with two engines are altogether more economical than single-engine cranes. Fuel consumption of a superstructure engine and an undercarriage engine in the five-axle category were measured live on location. Both engines idled for the whole day and a digital display showed their fuel consumption in real time. The result was that the superstructure engine producing 129 kW (175 HP) used at least 1.9 litres per hour less fuel when idling than the undercarriage engine producing 390 kW (530 HP). Thomas Schramm elaborates: “This result is of course only half the truth, since as everyone knows, cranes don’t just operate in idling mode. But if we look at the latest publications on the subject, it does seem indisputable that the idling that occurs during waiting periods does at least constitute a major proportion of crane work. If you also consider that engines are in practice rarely switched off – firstly because the air conditioning in the superstructure cab would no longer function, and secondly because crane drivers and construction site operators wish to remain on standby to lift at short notice – then this result does seem very significant.”

As well as the fuel saved during crane operation, TADANO emphasizes that the engines are subject to less wear in two-engine arrangements, which effectively means double the lifespan for each engine or a higher resale value. In answer to the question of whether two engines require twice as much maintenance, Christian Schröder, Sales Manager for the German and Austrian markets, says, “Both engines do of course need to be serviced regularly, but service intervals generally depend on hours of operation and the maintenance costs on a smaller engine are much lower than those of a big engine. And fortunately you can organize services so that operating downtimes caused by maintenance are eliminated.”

As well as these economic aspects that are so beneficial to crane owners, TADANO believes there are advantages for crane drivers too. In a two-engine crane the superstructure engine is always behind the driver’s cab, ensuring that exhaust and noise pollution are minimized across the whole turning range, which helps operators work with greater concentration. Then there is the fact that there is always a second drive unit available on the crane, which can be beneficial under certain circumstances such as jump-starting and emergency operation.