Intro 

The existing logistics ecosystem has been optimized over decades, regulated by law and constrained by the technical capabilities of traditional trucks and trailers. Due to significant downward cost pressures, profit margins are exceptionally narrow.

The electric trucks entering the market today have key limitations compared to their diesel counterparts. Specifically, the range and payload are different from what shippers are used to today. In order to make electric trucks a viable option, they have to work in the current ecosystem. 

In this Insights piece, we look deeper into how the higher curb weight of electric trucks affects their maximum payload and explore potential solutions to make them a competitive alternative. We are firm believers of sustainability, which doesn’t work if the solution is not sustainable.

Definitions

1. Gross Combination Weight: The Gross Combination Weight (GCW) is the weight of the entire combination of truck and trailer. There are both technical and legal limitations on the GCW. 

2. Gross Vehicle Weight: The Gross Vehicle Weight (GVW) is the weight that a vehicle itself puts on the road, i.e., excluding a trailer. The maximum GVW is determined by technical and legal limitations.

3. Legislation: The EU has implemented changes in its regulations enabling countries to allow for additional weight for electric trucks. This is an additional 2 tonnes for both the GCW and GVW. All legal limits referenced in this case study are based on German regulations in effect at the time of publication.

4. Kingpin pressure: In this article, we define kingpin pressure as the weight transferred from the trailer to the truck. The maximum kingpin pressure is determined by subtracting the truck's empty weight from its maximum Gross Vehicle Weight (GVW). This calculation yields the maximum weight the trailer may transfer to the truck without exceeding the maximum GVW.

5. Distribution of payload: The way the payload is distributed over the trailer can differ depending on how the trailer is loaded. In this article, we have assumed that the payload is divided evenly over 33 EU pallets (i.e., the center of gravity is 6600mm from the front wall of the trailer).

The challenge

This article utilizes a case study wherein a specific client project required both long-range electric trucks and substantial payload capacity. 

GCW challenge

Electric trucks currently have a lower maximum payload capacity compared to diesel trucks due to their heavier weight: this is the case even with the updated legislation that permits an additional 2 tonnes to the GCW. The example below showcases the impact of the heavier trucks on the maximum payload capacity.

Table 1: Impact of curb weight on max payload capacity

Payload distribution challenge

The payload capacity of electric trucks can be diminished compared to diesel trucks, often due to reaching the Gross Vehicle Weight (GVW) limit at lower payload levels.

Consider the maximum kingpin pressure, defined as the maximum weight transferred from the trailer to the truck until the GVW limit is attained.

In Figure 1, a diesel truck weighing 8 tons with a GVW of 18 tons has a maximum kingpin pressure of 10 tons. With the specified trailer, this results in a maximum payload of 23.2 tons, meaning this payload generates 10 tons of kingpin pressure in that trailer configuration.

If this payload were applied to a long-range electric truck, the resulting GVW would be 21.7 tons, exceeding the legal limit of 20 tons. Consequently, the payload must be significantly reduced to comply with legal regulations.

Figure 1: Impact of weight distribution on max. payload

Bridging the gap

To address these challenges, Einride employs three solutions, either independently or in combination.

Lightweight trailers

Trailers, specifically those with reduced weight such as the Berger EcoTrail and Kögel Light, offer considerable payload increases compared to conventional curtain trailers. Our case study demonstrates that employing a standard Lightweight trailer yields a 2-tonne increase in effective payload over standard trailer usage.

Trailer axle placement 

Relocating the trailer axles further toward the front results in a greater proportion of the trailer's weight being borne by these axles. Consequently, the weight exerted on the truck is reduced, i.e., the kingpin pressure is reduced. Mitigating kingpin pressure helps to address the payload distribution challenge.

The redesigned trailer, created in collaboration with an innovative trailer manufacturer, features repositioned axles (see Figures 2 and 3). This modification yields a 3.2-tonne increase in effective payload capacity over a standard lightweight trailer.

Figure 2: Dimensions of a standard lightweight trailer

Figure 3: Dimensions of the lightweight trailer with repositioned axles

Wabco OptiLoad

The Wabco OptiLoad system shifts weight from the truck to the trailer. When activated, it reduces kingpin pressure, thereby decreasing the load on the truck's axles and increasing the load on the trailer's axles. This is achieved by lowering the pressure on the trailer's rearmost axle, which consequently increases the total weight supported by the trailer's axles.

Figures 4 and 5 below show the kingpin and axle loads for a lightweight trailer with special axle configuration. The maximum payload is limited by the kingpin pressure, which is maximum 8.3 tonnes. As can be seen in Figures 4 and 5, the payload of the trailer with OptiLoad increases, a change entirely covered by adding additional weight to the trailer’s axles. 

Figure 4: Loads on kingpin and axles of a Berger special axle config trailer without OptiLoad

Figure 5: Loads on kingpin and axles of a Berger special axle config trailer with OptiLoad

Conclusion

To summarize the findings, we have created Table 2 below. 

Table 2: Summarized results of the different solutions to the Payload challenge

Currently, the lightweight trailer featuring a specialized axle configuration and OptiLoad technology is deployed at a client site. This equipment serves continuous, 24/7 transport of goods from a manufacturing facility to a distribution center. Since the start of operations, this trailer deployment has executed over 300 monthly shipments, each accommodating a payload of up to 25 metric tons.

Electric trucks are here to stay and will, within the coming years, play a central role in the transportation industry. It is therefore essential that we find ways to overcome challenges with electric trucks and work together in setting up a standardized transportation system where these trucks compete on equal terms. 

If you want to electrify your transports but cannot find a sustainable way to do so, please reach out to us for a discussion on how we can best support you

Bas Verdaasdonk

info@einride.tech