Don’t Judge an RT Forklift by Its Horsepower

For rough-terrain forklift manufacturers, another EPA Tier standard is in effect in the quest for clean-burning diesel engines.

In the May 2012 issue of Lift and Access, editor Mike Larson pointed out that the non-road diesel engine industry would be dealing with the EPA’s Tier 4 Interim (Tier 4i) regulations kicking in that year. These new standards would apply to engines having ratings from 75 to 174 hp.

For many rough-terrain forklift models, these regulations translate into a 90% cut in the amount of allowable particulate matter emitted, compared to the Tier 3 level. They would also reduce emissions of nitrogen oxides (NOx) by 50%.

While much of the attention is focused on the changes with diesel engines, it has been up to RT equipment manufacturers to come up with the chassis to accommodate the Tier 4i-rated engines.

Meanwhile, users wondered whether the machines would deliver the speed and power to get the job done on their construction sites, in their fields, or in their orchards, despite the new emission controls. From my vantage point, RT forklift manufacturers met this challenge head on to not only satisfy industry regulations, but in some cases, also address customers’ needs for fuel savings and lower overall owning and operating costs. Improved efficiency

These new requirements meant thinking beyond horsepower as a performance criterion. In focusing on Tier 4i compliance, Case spotted this as an opportunity to introduce design features that would increase efficiency and lower the cost of ownership.

We opted to employ Cooled Exhaust Gas Recirculation (CERG) with the help of a turbocharger to balance both regulator and customer demands. The CERG solution includes a diesel particulate filter (DPF) aftertreatment system.

The bottom line for an RT forklift is to deliver materials from point A to point B as quickly as possible. The challenge, as the industry moved to address this next level of EPA regulations for diesel engines, was to avoid larger engines that would sacrifice maneuverability and operator visibility. This is especially true since rough-terrain forklifts deal with restricted spaces and must maneuver through any number of narrow passages, making a larger chassis out of the question.

Manufacturers haven’t gone away from horsepower as a criterion; instead, they have reduced engine displacement. Limiting engine size has let the industry maintain the chassis size that fit Tier 3 engines while achieving fuel efficiencies and keeping horsepower in the 74 to 79 range for productivity.

In some cases, the resulting benefits include the same clear cab visibility as with previous models, along with zero tailswing, allowing the forklift to make turns in tight areas. Because cab design structure hasn’t changed, users who have moved material with a Tier 3 machine can climb into a Tier 4i cab and feel right at home. As a result, these easy-on-the-environment forklifts can work within the designated environment.

Electronics also have played a crucial role in enabling the industry to get more out of smaller engines. At Case, for example, we have been able to go from a 4.5- to a 3.4-liter engine with no effect on our ability to meet horsepower and torque demands, or user expectations.

Engines in the new Tier 4i models are using electronics across the board to replace many mechanical components. The result is more responsive operation, quicker and easier adjustments, remote diagnostic possibilities for up-to-the minute maintenance, and the ability to provide more operational data in the cab. Moreover, incorporating electronics can open the door to future upgrades in other aspects of forklift operation.

Other improvements include piston redesign and timed multiple fuel injections that result in quieter operation and reduced engine vibration for more efficient combustion. In addition, boost-pressure valves smooth out pressure waves, lengthening engine life. Travel speed, lifting speed, and lifting height are critical in forklift performance. Fortunately, the combination of an engine that can deliver high RPMs by being better managed by electronics, coupled with adjustments in the hydraulic system, enables the new generation of forklifts to pick and raise loads efficiently.

Future advancements will lead to even more efficient operation through the use of smart hydraulics, as well as even more fuel savings brought about by increasing the use of electronics in the valves. Manufacturers will also look at maintaining transmission speeds, lifting speeds, and lifting height while decreasing horsepower through further developments in engine control electronics.

Horsepower will truly become a less important consideration over time. As our industry approaches the challenge of each level of EPA standards for diesel engines, rough-terrain forklift manufacturers will regard this not as a demand for compliance, but as a chance to go beyond compliance and re-engineer the machine to improve the entire owner and operator experience.

About the Author: 

Katie Pullen

Katie Pullen is brand marketing manager for Case Construction. She can be reached at