With telehandlers now equipped with Tier 4 final engines, it is important for the aerial rental industry to better understand the different engine technologies and industry regulations. This information will help you choose the right machines for your fleet.
Tier 4 final engines used in telehandlers have an important regulatory threshold that you need to be aware of — regulations are different for machines with engines below 74 hp from machines equipped with engines over 75 hp. Engines below 75 hp do not require the after treatment that higher horsepower engines require. Machines with engines larger than 75 hp require one of two additions to meet today’s stricter emissions requirements: A Selective Catalytic Reduction (SCR) system or a Diesel Particulate Filter (DPF).
A DPF is a component on a Tier 4 Final engine that is designed to remove diesel particulate matter, or soot and ash, from the exhaust gas of a diesel engine. When the soot and ash inside the filter reaches the filter’s capacity, the machine needs to regenerate. Tier 4 Final engines are designed to regenerate in one of two ways: Active or Passive. With active regeneration, the operator must park the machine and turn on the regeneration feature. This feature enables the machine to “park and burn.” This means that the engine runs until the temperature is raised high enough to burn off the soot and ash collected in the filter. This process takes approximately 30 minutes and must be done at intervals prescribed by the engine manufacturer, which are dependent on the machine’s usage. With passive regeneration, the machine automatically burns off the diesel particulate matter while the machine is in operation.
A SCR is a technology system that injects a liquid-reductant agent through a special catalyst into the exhaust stream of a diesel engine to actively control emissions. In this case, the SCR has injectors that inject diesel exhaust fluid (DEF) into a chamber. The result is conversion of NOx to water and N2 in the exhaust.
Some engine technologies incorporate a combination of SCR and DPF technologies to meet emissions standards, but that type of hybrid system does not apply to telehandlers’ engines size classifications.
Machines with engines smaller than 75 hp typically only need a diesel oxidation catalyst (DOC). Similar to SCR, a DOC serves the function of a catalytic converter. However unlike SCR, there is no need to inject DEF fluid into these engines in order to meet emissions requirements. This is because the DOC converts the carbon monoxide to carbon dioxide using a honeycomb mesh coated in platinum.
One does not have to think too far back to remember the black clouds of soot and ash coming out of the exhaust pipes of construction equipment, and with these new Tier 4 Final diesel engines, this is just not the case anymore. Tier 4 engines go past the global perspective of the environment and have an immediate effect on the job-site with a cleaner environment for everyone around modern construction equipment.