Materials Handling

Burning issues

By Mark Nicholson

July 2019

The future of IC engine forklifts

The latest round of new EU emission standards has again focused attention on the challenges facing IC engine lift truck manufacturers and users. With the help of specialists from Cat® Lift Trucks, Mark Nicholson looks at current trends and discusses the way forward for this important market segment.

Sales trends

Between 2001 and 2018, total counterbalance forklift sales in Europe have flipped from 60:40 in favour of IC engine to a 60:40 advantage for electric. However, variations in these percentages between countries suggest major cultural differences in preferred power sources.

At one extreme, electric makes up 82% of counterbalance sales in Italy – up from 73% in 2001. At the other, IC engine forklifts still dominate in the UK – where electric’s share has only moved from 32% to 33% over the same period. Further comparisons are shown in Figure 1. Despite the overall trend toward electric, there is clearly a strong and continuing demand for IC engine products.


Figure 1: Percentage split between electric and IC engine counterbalance sales in 2001 and 2018

Figures comparing diesel and LPG forklift shares within the IC engine segment are not so easy to obtain. However, it is well known that European customers have always leaned more toward diesel, while Americans have preferred LPG. With its global development and manufacturing base, Cat Lift Trucks is equally well equipped to develop and improve technologies using both of those power sources, as well as electric.

“As the pressure to reduce emissions increases, and as electric trucks become more attractive for other reasons, both LPG and diesel customers are switching,” says General Manager, Equipment, Willem de Jong. “Some diesel users may swap to LPG, but most are likely to change directly to electric. The effort of dealing with LPG bottle swapping, storage and refuelling, together with the health and safety regulations surrounding those activities, will be unappealing or impractical to many. It may also seem an unnecessary intermediate step to those who feel that a move to electric will ultimately be inevitable.”

Challenges and responses

“Electric trucks are gaining market share largely because of their advantage on emissions,” IC Engine Product Manager Carmen van Boeckel comments. “In addition, today’s electrics are becoming more powerful, durable and weather-resistant than their predecessors, so they can handle some outdoor roles which previously required IC trucks. They also offer sophisticated electronically controlled features which create an excellent user experience.

“But the IC engine lift truck is here to stay, and we can expect to see continuing technological development in this area. The new Stage V EU emission standards, along with increasing pressure to reduce carbon footprint, are driving further improvements in efficient, clean-burning engine technology. We also expect to see technologies from our electric trucks applied to IC products, including hybridised power systems and additional driver aids.”

For LPG engines, the changes needed to comply with Stage V are relatively small and will result in little if any cost increase. For diesel engines it is much harder, and customers will eventually see hundreds or even thousands of Euros added to truck prices, depending on the model.

Willem de Jong adds: “In this new era, diesel forklifts will be more productive than ever, but customers will have to accept that the traditional simple diesel engine has become a thing of the past. Those older, mechanically controlled engines, built on many years of evolution, were well understood, very predictable in their applications and usually extremely reliable.

“The latest Stage V engines are much more sophisticated and fully electronically controlled. They have been subjected to rigorous testing programmes, of course, but they have yet to prove themselves to users in the marketplace. It will be an interesting time for forklift mechanics too, as they are used to maintaining engines without the use of a laptop.”

There will probably be a greater demand than in the past for refurbishment of the existing population of older trucks to give them a second or third life. Although simple diesel engines will be phased out and will never come back, they may take many years to disappear.


Innovation in IC engine design continues.


For heavy work in harsh environments, IC engine power is often the only realistic option.

What Stage V means

Stage V is the latest in a step-by-step EU programme to reduce harmful emissions from the engines of non-road mobile machinery. Beginning in the late 1990s, each stage has introduced increasingly stringent emission limits. These particularly target nitrogen oxides (NOx), hydrocarbons (HC), carbon monoxide (CO) and particulate matter (PM).

Stage V sees permitted levels of these substances in exhaust gases cut by about 96 to 97% compared to Stage I. For PM, which consists largely of soot, there are now limits on the number of particles emitted as well as the mass.

For engines with a power rating below 56 kW or from 130 kW upward, the new regulations have applied since January 2019. This typically covers forklifts with capacities up to about 5 tonnes or higher than about 16 tonnes. For those in between, Stage V will be implemented in January 2020. Transition arrangements will be in place up to 2022, so there will be no sudden shock to the market.

Norway, Switzerland and post-Brexit UK are amongst the non-EU countries which will probably apply the same standards.

To reduce emissions, engine designers will use a mixture of technologies including some or all of the following:

  • Selective catalytic reduction (SCR) – uses catalysts like urea or diesel exhaust fluid (DEF) to reduce NOx
  • Diesel oxidation catalyst (DOC) – converts HC, CO and some other emissions into less harmful substances
  • Ammonia slip catalyst (ASC) – removes leftover ammonia from the SCR process
  • Exhaust gas recirculation (EGR) – lowers peak temperature of combustion to reduce NOx and PM production
  • Diesel particulate filter (DPF) – traps soot particles
  • Exhaust after-treatment system (EATS) – combines several of the elements above

Increasing engine efficiency will also help, as lower fuel consumption means
lower emissions.

Rest assured, if you buy your forklifts from a reputable manufacturer with a European dealer network, like Cat Lift Trucks, they will comply with EU regulations. If, instead, you import them yourself from outside Europe, you will be responsible for ensuring they are compliant.

It is perfectly legal to continue using older trucks which pre-date the Stage V limits (although in some urban low-emission zones there are separate restrictions on the use of diesel machines). You can also confidently buy from existing stocks of new trucks which pre-date the new limits. These are only subject to the regulations which applied at the time they were placed on the European market.


Emission-reducing technologies include diesel particulate filters.

Continuing IC advantages

Despite the additional cost of complying with Stage V, particularly for diesel forklifts, IC engine trucks will still be substantially cheaper to buy than electric. Rugged IC engine lift trucks will be difficult to replace with electric lift trucks in tough outdoor applications, especially where loads are heaviest.

Both LPG and diesel offer virtually non-stop productivity, as they can be refuelled quickly – in contrast to the time-consuming battery changes and recharging of electric trucks. There is also interest in the ability of LPG trucks to do occasional indoor as well as outdoor work, if local rules permit.

Diesel forklifts continue to score highest on torque – for more powerful performance – and on operating economy. They are also the easiest to supply with fuel in remote locations with no mains electricity. They may even have a lower carbon footprint than an electric truck, if the energy used to charge the electric’s battery has been generated by burning fossil fuels.

“For many applications, in many areas, switching from IC engine to electric simply isn’t feasible – and isn’t likely to be a realistic possibility any time soon,” Carmen van Boeckel concludes. “Consider, for example, the huge practical difficulties involved in powering a large electric container handler. Or in running an electric fleet in a region which doesn’t have the necessary electrical supply infrastructure. We can safely say that diesel and LPG still have much to contribute to the world’s energy mix and to the materials handling industry.”