United Safety Introduces The Infinity Line – Passenger and Driver Seating & Suspension

Public transportation is shifting to the future, with increased investments in electric and hybrid vehicles, light-weighting, mobility solutions, and an eye toward Bus Rapid Transit. Representatives from United Safety said the company is prepared to help the industry with dynamic seating solutions that fit transit’s focus on these concepts.

The Infinity Line of transit seating by United Safety aims to help OEMs and transit agencies create additional flexibility, customize spacing and capacity, increase range, improve comfort, and become more sustainable.

“We have seen a shift in the thought processes of agencies and manufacturers in the transit industry,” said Joseph Mirabile, president and CEO of United Safety. “It is extremely exciting, and our product designs are meant to support these revolutionary changes in public transportation.”

United Safety debuted the Infinity Passenger Seat, Driver’s Seat and Driver’s Seat Suspension package at the American Public Transportation Association EXPO 2021 in November.

Infinity Means Flexibility 

John-Paul McGovern, vice president of engineering at United Safety, said that the Infinity Line represents the biggest update to transit seating in over a decade. Designed for all commercial city transit buses and most especially Electric and Hydrogen vehicles, McGovern said the passenger seat features an industry-leading lightweight design and is designed for comfort with modern riders in mind.

“The passenger seat has a host of features not available elsewhere in the market,” McGovern said. “All Infinity passenger seat cushions can be flipped up, locked up or locked down – a level of customizability that allows transit authorities additional flexibility.”

He added that the seats’ flip-up capability has a variety of uses, from everyday stroller storage to reducing occupancy in the wake of an event like COVID-19. United Safety strove for maximum flexibility and modularity for agencies and manufacturers when designing the Infinity.

“The modularity simplifies the amount of parts and minimizes maintenance,” McGovern said. “In most previous transit seating designs, there was a difference between the forward mobility area – where the seats mounted longitudinally are facing toward the center of the bus—and the rest of the bus seats. The longitudinal  seats are usually flip seats with various custom brackets, and the rest of the bus’s seats have a standard non-flipping design. With the Infinity, all passenger seats have the same flipping functionality.”

This parts commonality lowers the cost of maintenance – thus reducing acquisition costs for the end user, as well.

“With Infinity, we are aligning a product line’s design features with the thread lines of the transit industry,” said Ray Melleady, executive vice president of United Safety. “The industry is moving toward sustainability, equity, and inclusion, and those concepts are the design criteria for this new line.”

“The seats’ manufacturing reduces the carbon footprints of equipped vehicles, reduces the overall weight of vehicles, and improves access for riders with disabilities,” he continued. “It makes transit buses more effective at carrying people and aligns United Safety’s vision and mission with those of the transit industry.”

The Driver’s Seat & Suspension

Another major development for United Safety is the Infinity seat suspension and driver seat package for transit buses. McGovern said that the Infinity driver seat features a new computer-controlled suspension system to provide the smoothest ride available in all manufacturers’ bus models – as well as the industry’s lowest level of whole body vibration available in the industry.

“To date, drivers’ seats have generally been passive air-suspension seats,” he said. “They contained an air spring, which adjusts the height and the strength of the seat’s spring. They also contained passive, fixed rate dampers, which were meant to prevent the occupant from hitting the bottom or top really hard during ‘big bump’ events. Still, those seats are transmitting some degree of energy to the occupant.”

“This new, Infinity seat suspension,” he continued, “truly reduces that energy transmissibility as much as possible.”

“It’s a much more comfortable system that fits physically into all the different buses and transit environments out there,” he said.

The Infinity Seat Suspension for drivers features dampers which are damping-rate-controllable by means of computer system. Utilizing a suite of sensors, including an accelerometer and position sensor, the suspension determines the vehicle’s floor motion and performs calculations to update the seat’s damping coefficient in real time. McGovern said this occurs on the scale of milliseconds to optimize the occupant’s ride.

Designing the Infinity Series

Mirabile said that, while transit seats have seen piecemeal upgrades in recent years such as USB ports, the basic design of transit seats has needed an upgrade in order to meet the needs of current riders. Instead of representing another add-on, he said the Infinity Line was meant to be a redesign of the entire transit seat’s concept and functionality, as well an eye-catching visual upgrade. 

“We believe in it creating a very long-term sustainable public transit environment, and that’s why we made this investment now to support both our bus builders and our customers moving forward,” he said. “We think this is going to lead to continued increases in ridership, and thus more bus routes. These changes are increasing people’s mobility, and we believe a whole new wave of riders will see buses as a futuristic or modern transportation option.”

The engineering of the Infinity Passenger Seat started with industrial design and the finding of a target appearance and functionality. Then it was a matter of doing the mechanical design, or moving from the conceptual to practical phase. The weight optimization effort involved Finite Element Analysis (FEA) and other simulations.

“Every component in the assembly was analyzed for optimization purposes, including a full suite of FEA virtual testing,” McGovern said. “The parts were prototyped using 3D printing, and then parts and components were released to final mold and production design. It was a cutting-edge design process, with many virtual simulations to avoid excessive changes in prototyping.”

McGovern said the Infinity driver seat and suspension design was almost three years in the making. The first challenge was designing and implementing an extremely low-friction suspension. This took a few design iterations, because the performance goal would not be possible with a big, sticky suspension containing significant free play and friction. The United Safety engineering team accomplished this feat with a computer-aided design simulation followed by many trials of physical testing. 

From there, McGovern said the team worked through the mechanics of damper placement, damper type motion ratios, mount types, and other intricacies.

“It was no small task to design this seat, but it has been accomplished and now we are working through the volume manufacturing process.”

“When I interview transportation managers, they say they want increased aisle width and have more comfortable passenger seating – which are competing objectives,” Melleady said. “You can’t typically do that with capacity, and yet our engineers have found very creative ways to reduce weight, improve ergonomics, and increase the space that’s required inside these newer vehicles. Future developments in the bus driver seat market look to bring even more advanced features to the industry such as advanced weight optimization including composite technologies and potentially even carbon fiber components.”

Infinity and Beyond

Mirabile said that, coming out of APTA EXPO 2021, he has heard near-universal excitement from OEM partners and agency customers.

“There is a high level of excitement among the manufacturers as we exit the COVID-19 downturn,” he said. “They’re excited to see supplier partners like us come to the table with new products, especially products that align with their own future directions.”