With $25,000 in prizes and several categories of awards, there was not one team that did not take home some sort of honor during Parker Hannifin’s Chainless Challenge earlier this month at the Great Park (the old El Toro Marine base) in California. The year-long event challenges engineering students across the country to design and build a working bicycle that does not use traditional gears and chains as its power source—but rather, some form of fluid power.
This was the eighth time Parker has held the event in the last 10 years and each Spring, the students come up with different, innovative designs. Overall winners for 2015 were Cal Poly San Luis Obispo, which had won in 2006 and 2008. The Cal Poly team scored 1,325 points, and was closely followed by University of Illinois at 1,310 points, then Murray State University with 700 points and University of Cincinnati with 675. The teams were judged on their designs, papers, presentations, and, of course, how they fared in a sprint race, distance race and efficiency race.
Featuring a low weight of just 125 lb, compared to some others who weighed in at well over 200 lb, Cal Poly’s design featured a hydraulic pump and motor system to create mechanical rotation at the motor. Cal Poly students said during judging that for them, reliability was key to their design. And not surprisingly, they were right, as their design won first in several categories, including reliability. In addition, this design was one of the top performers, coming in first for the time trial and efficiency race and second in the sprint race. Cal Poly was one of only four of the nine teams that was able to complete the 6-mile distance.
According to Cal Poly’s paper, their design features a front and rear drive unit to efficiently use two F11-5 pumps. A custom bicycle frame provides the mounting points and strength necessary for the hydraulic circuit, also incorporated valves and an accumulator and reservoir for energy storage and regenerative braking. A clutch allowed the team to efficiently coast and easily walk the bike.
In second place was the University of Illinois at Urbana-Champaign. Dubbed the FL.E.E.T. (Fluid Efficient Energy Transport) team, they chose a tricycle design, weighing in at 215 lb with fluid and 185 without. The students said the bike could reach top speeds of 25 mph for sprint races and cruise at about 13 mph. They reworked the electronic controls and the regenerative braking system. And to fully use the advantages of manifolds, members of the team enrolled in an online course through the University of Minnesota to learn more about hydraulics and manifold technologies, as the manifold was key to their design.
Sandy Harper, Parker’s Corporate Technology Liaison Manager, said this is not the first time these engineering students needed to enroll in a class to learn about fluid power. In fact, at the Illinois Institute of Technology (IIT), they developed a fluid power class based on the Chainless Challenge experience after their first attempt four years ago.
Illinois Institute of Technology, which did not place in the top four this year, was the only team to use cylinders in its design. Essentially, the student’s presentation indicated that two sets of paired cylinders cycle fluid back and forth between each other to transmit power from the pedals to the rear crankshaft. So as you pedal, one side is high and the other low, and this helps build up pressure in the accumulator. The design was the most lightweight, coming in at a mere 86.6 lb.
The bicycle styles all varied, from tricycle to standard bike and even one from the University of Cincinnati that was more like a rowing machine. But as Harper said, no matter what design they chose, all of the teams presented good, working designs and had professional presentations and papers that truly taught them what working on an engineering design project will really be like.
“In the end, it’s all so fun,” Harper said. “This is a really good experience, as they are given a task and they have to design and build and test it. This is what they’re going to experience in industry and they all really enjoy getting that experience.”