My work at Xos Trucks primarily focused on the heavy duty box truck and semi truck project but towards the end of my tenure at Xos I made some of my most significant contributions to the step van product.

MDXT & HDXT Development

Battery Mounting Structures:

At Xos trucks I started as a Design Engineer working on the Class 8 heavy duty tractor.

One of the first projects I had was the design of battery mounting structures for the next generation Xos designed battery packs. These battery packs where extremely long, water cooled and had an impact on several systems throughout the vehicle including suspension, steps and cross members. The battery pack also required a complete redesign of the water cooling system as the existing cooling systems were only intended to cool the motor and little else.

Suspension:

We were trying to have an extremely short wheel base in order to have best in class vehicle turn radius however, the off the shelf suspension hangers from our existing suspension vendor wouldn’t work. I created a concept design of a low profile suspension hanger and started working closely with Hendrickson to get it manufactured and integrated into a suspension kit for us that we could simply bolt in place. As time progressed and people progressively left the company I became the lead person working with Hendrickson to get both front and rear suspension systems designed and delivered.

Pneumatic Systems, Brakes and Suspension

The design and integration of the pneumatic systems was also an early project of mine when I started at Xos. We had our brakes selected for us so it was up to me to size the system to be able to meet FMVSS regulations regarding brake systems while also providing enough overhead to operate the air suspension system.

One of the biggest challenges on this project was not necessarily the design work but simply finding a vendor who would supply us parts. Xos was still a relatively small company compared to other truck manufacturers and there are very few companies offering parts meeting commercial vehicle requirements. This is particularly true of electric commercial vehicles where only one or two parts may exist. There were multiple occasions where I would spend a few weeks working with Bendix or other vendors to size and select components only to be told that we were too small of a company for them to want to actually sell us parts.

Cooling System and Under Hood Architecture

When cooling system design and development became I priority I began working with Modine on the development and integration of a completely new cooling system for the medium and heavy duty MDXT and HDXT. Modine provided recommendations on major components and assisted with the sizing and design of the radiator stack and I was responsible for locating all of the cooling system components in the vehicle, designing and creating cooling system hose and tube layout as well as sourcing vendors for hoses and tubes.

I learned during this process that if anything electric vehicles are if nothing else cooling systems with motors and batteries attached. The cooling system is such a major component of the vehicle that it was necessary for me to also reconfigure and optimize the components of other vehicle systems.

Through this process I tried to create designs and select components that could be used universally across vehicle platforms. Being able to take this approach from the start not only allowed us to reduce costs long term but also allowed us to create different vehicle configurations quickly and easily using existing components.

Step Van Development

Step Van Cooling System

Priorities in the company gradually shifted over time and the heavy duty product line became less of a priority while completing and releasing next generation step vans became a bigger priority. As a result I put my heavy duty truck work on pause and focused full time on getting the step van cooling system across the line.

Modine was also helping us with the development of the step van cooling system design and since I already had rapport with the Modine team so it was easy to jump in and take lead on the step van cooling system as well. This cooling system had been in development for several months but but there were several areas that needed immediate improvements for serviceability, reliability and reduced cost.

I was able to quickly design a cooling system that reduced the system cost by 33% while eliminating a significant number of points of failure. In addition to this I also pulled the step van cooling system closer to the heavy duty vehicle cooling system by using common tube and hose diameters along with materials we could easily order in bulk. Serviceability was also improved through relocating joints to areas that were easier to access and relocating or eliminating anything that required regular service.

Step Van Battery Mounting Structure

Another area where I contributed significantly was the step van project was in the saddle battery mounting structure design. I knew this was an area that the team was struggling with for the better part of six months but had yet to come up with a solution that was simple, easy to manufacture and most importantly, FEA simulation.

I took a bit of time to review simulation results and identify that one of the biggest issues of the existing design centered around where the support structure transitioned below the frame rails of the vehicle. This was essentially a point where the mass of the batteries were trying to bend the support structure around the bottom of the frame rail adding significant stress. I additionally identified that only half of the battery mounting structure was actually performing any work. The outer part of the structure contributed little to supporting the mass of the batteries and thus only contributed to additional weight and cost that was completely unnecessary.

Once I identified these two pain points creating a solution was relatively straight forward.

1.) Design a structure that does not see bending moments around the bottom of the frame rail.

2.) Design a structure where the entire structure sees stress evenly.

3.) Keep it simple, light weight and cheap.

To accomplish these objectives I came up with a design that started with two structural arms the height of the frame rail and extending outward the width of the battery packs. From these I designed a shell like structure that hung from the two arms with one battery pack inside the shell and the other on top of the shell between the arms. This turned out to be an incredibly efficient and flexible design since the arms allowed the entire clam shell to distribute the stress evenly while also having the flexibility to be adjusted to match existing holes in the frame rails.

Some added bonuses of this design included the ability to decouple the battery structures from the frame rails through the use of rubber dampers so there was minimal impact on frame stiffness and the entire system was incredibly easy to install and remove since battery packs could be completely assembled off the vehicle and then lifted into place from the bottom and secured with four bolts.