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Technical Innovations
Barry Controls helps Sears with shock and vibration
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Barry Controls and Sears Seating engineering teams developed the torsional spring seat suspension as an alternative to traditional shock and vibration damping.
The torsional spring, which is directly beneath the operator and forward in the suspension area, is said to offer exceptional ride performance.
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Sears Manufacturing has enlisted the help of Barry Controls, a designer and manufacturer of shock-, vibration-, and noise-control products, to help lessen the jolts, jostles, and bumps experienced by operators of heavy equipment through improved seating. Sears Seating, a $100 million-a-year, privately held company owned by the fourth and fifth generations of the Sears family, supplies products to companies such as Deere & Co., Caterpillar, NACCO, and Melroe.
To maintain its market-leading position, Sears Seating must constantly develop new and unique technologies. According to Kent Wichelt, Vice President of Off-road Engineering, "The Sears engineering team decided that traditional methods of damping vibration and larger impacts in industrial and light construction seating no longer served their purpose." Sears was using steel springs to isolate shock and vibration, which requires numerous mechanisms and different types of attachments. The large number of components required by traditional seating resulted in high costs in a cost-sensitive market.
In the attempt to streamline and simplify its seating products, Sears enlisted Barry Controls to help it design and engineer a rubber torsional spring for seat suspensions that would absorb vibration and larger impacts and reduce the number of components. However, the product was new to both companies.
The Sears team worked very closely with Barry engineers to develop this new technology. The torsional spring is located in the scissor mechanism that joins the seat's upper and lower suspension housing. The outer portion (drive arm) of the spring bears against the scissor shafts, while the inner spring is attached to the lower housing. The spring sits directly beneath the operator, forward in the suspension area. The resulting product offers a simple, compact, and clean design with few moving parts. It is packaged well and is notable for its simplicity, updating the traditional means of isolating vibration and shock.
Both Barry and Sears put the torsional spring through vigorous testing to prove that the design's operation would be much smoother. Production of seats using the new design began in the second quarter of 1999, and Sears' European operation, Sears Europe, has also started producing seats with the torsional spring.
For more information from Barry Controls, call 617-787-1555 or circle 418.
SAE Off-Highway Engineering April 2000
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