AIA: Tilt Table Simplifies Testing
Established in 1974, E-One Inc. (Ocala, FL) employs more than 1,300 people and manufactures fire and rescue vehicles used by fire departments, rescue and EMS squads, and airport emergency crews.
One of the requirements for E-One's aircraft rescue and fire fighting (ARFF) trucks is that they meet a static rollover threshold in accordance with SAE J2180. Put simply, the SAE specification determines the angle at which the trucks will tip over.
E-One previously performed this test using two tilt tables that were manufactured in-house and spaced approximately 25 feet apart. This equipment, however, began to fall short for two reasons. First, today's trucks are heavier than in years past. Second, it has always been difficult to control the tilt angle by coordinating two independent hydraulic tables.
To solve the problem, E-One contacted the West Bend division of Bushman Equipment Inc. (Butler, WI), which built a single, high-capacity table to take the place of the two smaller ones. Based on projected loads, the tilt table was built with a drive-on top and measures 11 by 40 feet, with enough capacity to tilt loads weighing up to 150,000 pounds. In its folded-down position, the table is about 3 feet tall. E-One added concrete ramps leading on and off the table.
The table was manufactured at the Bushman West Bend facility in Menomonee Falls, WI. It consists of two main structures-the base and a tilt top where the truck is tested-which are hinged along one side. Tilting is performed with five, 7-inch-diameter dual-acting hydraulic cylinders, operating at a system pressure of 2,000 psi from a 25-hp hydraulic power unit.
During a test, the truck is driven onto the table, and its axles are secured with chains. The truck is tilted to the point where the tires begin to lift off the table. This rollover threshold is then recorded.
Since the table is used outdoors, all controls are housed in NEMA 4X stainless steel cabinets. The operator's console is equipped with operating switches and a position readout. Once energized, the table tilts at a rate of 0.25 degree per second. An inclinometer is incorporated into the table. Digital readouts are located on the operator's console and on a separate 6-inch, freestanding scoreboard visible to everyone in the test area.
According to E-One manufacturing engineer Greg Hofmann, the table's precision and ease of use has improved his company's ability to deliver quality products in a timely manner.
"The stability of any vehicle is determined by a low center of gravity," Hofmann says. "This tilt table not only allows us to test ARFF vehicles, but also a host of other trucks...With this test data we are now determining critical center of gravity information which is crucial as we develop and refine our designs. This gives E-One a sharp, new competitive edge in the marketplace."
For more on heavy test and material handling equipment, call 800-558-7850, visit www.westbendequipment.com or eInquiry 2.