Clean diesel engines underground
Clean diesel engines underground

Leveraging Clean Diesel in Underground Applications

By Caterpillar | Posted September 19, 2022

Today, most mining companies have focused safety, community and sustainability goals. Reducing emissions to limit environmental impact and comply with regulations is a key part of meeting these goals.Today, most mining companies have focused safety, community and sustainability goals. Reducing emissions to limit environmental impact and comply with regulations is a key part of meeting these goals.

Emissions present an additional challenge for underground mines. Ventilating a mine hundreds of meters underground is both difficult and costly, but it is necessary in order to ensure that people can work safely and comfortably — and to keep air temperatures suitable for equipment.

“We know carbon reduction, air quality and safety are monumental issues for our customers, and we are always looking for new ways to help them meet those challenges,” says Paul Bitter, Product Manager for Cat® hard rock vehicles.

Caterpillar offers several solutions to reduce machine emissions, including retrofittable filtration options and engines meeting the strictest emission standards.


“One of the most effective solutions we offer for lowering emissions is EU Stage V compliant engines in our machines,” says Bitter.

Stage V emissions packages are available for several Cat underground hard rock loading and hauling machines, including the R1700 and R2900 load-haul-dump (LHD) machines and the AD45 and AD63 trucks. The AD45 solution is also available as a retrofit for the older AD45B.

Cat engine and underground machines


The R1700 underground loader was Caterpillar’s first machine equipped with an EU Stage V engine. According to Bitter, the R1700 was redesigned in 2018 with a focus on reducing emissions, improving fuel economy, increasing the machine’s capacity and upgrading its hydraulic performance.

“Our emissions controls start inside the engine — where air circulation, high-pressure fuel injection particle size and pre-ignition injections — as well as our NOx reduction system (NRS) — play a part in reducing emissions,” he says.

Complementing these engine controls is the Cat Clean Emissions Module (CEM), an aftertreatment solution that includes a Diesel Oxidation Catalyst and a Diesel Particulate Filter (DPF). The CEM system also uses diesel exhaust fluid to further reduce NOx emissions.


Cat Clean Emissions Module chart


“Cat engines with aftertreatment have nearly 170 million hours of proven field performance,” says Bitter.

The R2900 uses the same system as the R1700, but required some upscaling in order to work in the larger machine. “To accommodate the aftertreatment package, we upsized the modular R1700 engine-end frame design to accommodate the Stage V engine and aftertreatment” says Bitter.

“The R2900 represents a very important size class for our customers in Europe, so it was critical that we bring this machine up to compliance early,” he says.

Caterpillar also offers EU Stage V engines for two underground trucks, the first of which was the new AD45, the manufacturer’s most popular size class.

“In developing our new AD45, we also found a way retrofit the engine and aftertreatment solution to the AD45B This represents a substantial benefit for our customers running this earlier-generation truck,“ Bitter says.\

For one mine in Western Australia, retrofitting their existing fleet with emission controls saved millions of dollars and is enabling their existing fleet to complete its lifecycle.

“One of the best opportunities for upgrading emission controls is during a machine rebuild,” says Bitter. “Most of our customers understand that their Cat machine is built to be rebuilt, and there’s no better time to upgrade the machine than when it’s already scheduled for downtime.”

The other truck with an available Stage V solution is the 63-tonne (69-ton) AD63 the largest and newest Cat underground truck. Its Cat C27 engine makes use of the same engine controls and NRS found in the smaller LHD engines. Additional design work was done to meet Stage V standards without the use of a DPF or DEF.


In addition to these EU Stage V solutions, Caterpillar offers a Diesel Particulate Matter reduction solution called the Wall Flow Filter. According to Bitter, this filter captures particulate matter and reduces it to below U.S. EPA Tier 4 Final levels without any impact on machine performance.

Wall Flow Filters are available as a retrofit kit and are integrated with the machine’s health monitoring systems. Wall Flow Filters can go as long as 3,000 hours between cleanings under normal operating conditions and have a service life of 10,000 hours, which lines up with the standard timeline for machine rebuilds.


Cat filters




Cat underground loaders are built to stand up to the harsh, unique challenges of underground mining, doing everything from increasing productivity and efficiency to improving safety.

Hard Rock Loaders
Hard Rock Loaders


With a fuel-efficient engine and the most durable components in the industry, Cat underground trucks offer a reliable haulage solution and a low cost per ton.

Hard Rock Trucks
Hard Rock Trucks