RFA Minnesota Engineering: Newsletters: Raising the Bar for Aerial Lifts

Featured Article: Altec and RFA Raise the Bar for Aerial Lifts

Altec Industries creates new products that promise the highest productivity, the lowest maintenance cost, and the longest life for the utility, telecommunications, and tree care markets from its 25 sites in North America. When Altec conceptualized a new series of aerial lifts, it leveraged the product engineering and stress analysis talents of RFA/Minnesota Engineering. RFA is a flexible organization with a distinctive style of working with clients that stresses continual communication and client involvement.

To meet requirements specific to utility and forestry jobs, Altec envisioned a next genera-tion telescoping articulating aerial lift with a superior side reach plus the ability to carry a 600-pound payload. Altec wanted rapid product development. RFA met Altec’s schedule by conducting product design concurrent with stress analysis and detailed documentation to compress the development timeframe.

RFA’s style includes cost-effective project teams that balance skill and experience levels. The RFA Project Engineer orchestrated a team that included four engineers/designers. The team kicked off the project with Altec engineers from Creedmoor, North Carolina, and Altec project sponsors from St. Joseph, Missouri. Throughout the project, twice-weekly reviews were conducted using interactive web collaboration software so that the team could simultaneously view and critique 3D models of design.

Rugged reliable reach

RFA’s design challenge was to keep component parts lightweight so that the mobile elevated work platform could carry 600-pounds, and to extend the reach of the boom up to 60-feet. Workers can park alongside a road, and reach over a ditch to access a power line or tree limb, on uneven terrain if necessary.

"RFA responded quickly to changes during the concept phase. When it was determined that one aspect of concept would cause theTA60 to be overwight, the RFA team stayed late that night and revamped the geometry to rough out a revised concept for our meeting the next morning."

-Altec Lead Engineer

RFA began design development work using Altec’s original CAD concept drawing. What eventually became known as the TA60 End Mount combined a 600-pound payload with two articulating booms and one telescoping boom mounted to a rotating pedestal on a truck chassis. The RFA team examined the boom range of motion from ground level to the highest reach of 60-feet, and from the rotating pedestal stowed on the truck chassis to the longest side reach of 35-feet.

Strong and safe

"We checked the stress of every pin, gusset, glued joint, and structural component throughout the range of motion. In the end, we had a high level of confidence in the final design."

-RFA Project Engineer

FEA visually depicted stress results and allowed RFA engineers to see detailed stress results throughout the interior and exterior of the pedestal and booms. Areas with high stresses required changes to either the design or the materials. Using RFA’s top-of-the line ANSYS and Nastran simulation tools, multiple design iterations of the entire TA60 End Mount could be evaluated in a single day. FEA focused the design effort early in the product development process, minimizing the need to make late changes during reliability testing. RFA’s parallel path engineering and stress analysis culminated with the creation of manufacturing drawings.

Altec lifts people higher

As the design of the TA60 aerial lift neared completion, RFA finalized the drawing documentation to meet Altec standards. To expedite the manufacturing procurement process, drawings of long lead items were completed first. Further development emphasized modular designs. RFA worked on the TA50 and TA55, to complement the TA60, which was rescaled and optimized to a 50-foot unit, then re-assembled using shared components between the 50- and 60-foot units to create the TA55.

RFA worked with Altec so the TA60 could be manufactured easily within Altec’s existing production system capabilities and standards. RFA’s manufacturing drawings detailed materials and sizes, clearance fits, welds, and machining. RFA aligns to its clients’ internal practices and standards during product design, stress analysis and production of manufacturing drawings. Altec’s lead engineer explained,“RFA can flex their schedule and staffing levels to meet the constantly changes needs of a design effort.”

As Altec prepared for prototype validation testing, RFA’s final stress results identified locations for placing strain gauges during cycle testing. ANSYS and Nastran simulation tools identified load cases that are difficult to test, and helped monitor locations that are difficult to strain gauge. Cycle testing simulated a lifetime of use in months. Success was achieved when test results correlated with both classical structural engineering calculations and FEA.

RFA measures success by tracking repeat customers, and Altec is highly satisfied with its ongoing partnership with RFA. RFA and Altec have since partnered on projects out of five Altec design centers located across the country from Duluth, Minnesota, to Creedmore,North Carolina. For instance, when Altec built a new factory in Shelby, North Carolina, RFA provided short-term staffing needs.

RFA Minnesota Engineering builds success

RFA provides engineering services to original equipment manufacturers in the utility, mining, construction, agricultural and defense sectors. RFA extends its clients’ existing in-house engineering capabilities with the ability to consistently execute complex projects and provide out-of-the box problem solving capabilities. RFA has provided these services to industry-leading clients including Caterpillar and John Deere continuously for decades. More than 200 manufacturers across the United States have leveraged RFA’s mechanical, structural, and electrical system design to reduce product development time and get to market ahead of their competitors with superior products.

Over 90 percent of RFA’s business comes from repeat clients. With 225 employees, RFA hires, trains and retains qualified and motivated professional staff. In 2008, RFA expanded its design center in Eden Prairie, Minnesota by almost 40%. Another 125 professionals have long term assignments at RFA client facilities, bringing its staff to a total of 225. RFA has the people, processes tools, and expertise to make projects succeed.

Concurrent with design development, RFA completed its stress analysis. The goal was strong but lightweight component parts to increase payloads at all reaches, and to keep manufacturing costs low. RFA developed rigorous classical structural engineering calculations to analyze stress as the shape, material, and weight for each component part evolved. With hundreds of engineering calculations, RFA engineers/designers examined structurally significant components through all operational ranges. Each component - booms; hydraulic cylinders; glue joints; pins and bearings - was cross-checked against Altec's in-house design and production standards. Classical structural calculations flagged problematic load cases for finite element analysis (FEA).