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There are a lot of safety issues for an operator to watch for: falling objects, fire, debris, holes and dozens more. But how do you protect an operator from something he can't see?

Noise, vibration and harshness (NVH) is a serious health issue facing operators, but bigger ear plugs and thicker seat cushions aren't going to solve it alone. When deciding how to conquer the NVH forces, it may be best to know what the sources of noise, vibration and harshness are.

Vehicle noise can derive from a variety of places — engine, muffler, fan, hydraulic system, accessories such as gears, chains and other vibrating components — and each system has a multitude of noise reducing solutions.

Perception of noise directly influences a customer's acceptance of a product. "The overall noise level of our products is the parameter that is documented in product literature, but it's the customer's perception of sound quality that is the true measure of perceived product quality," says Mike Beyer, technical specialist - NVH, Eaton Corp., Eden Prairie, MN.

Noise is a wave

Noise: According to NVHmaterials.com, both structural borne and airborne noise have two unique ways of treatment. Structure borne noise is solved through means of damping (no, not dampening, there's no need to get anything wet) and isolation. Airborne noise can be blocked by barriers (walls, thick glass) or reduced by absorbers, such as foam insulators.

Vibration: Whole body vibration (WBV) deals with the transmission of vibration into the human body and the effects that vibration can have on an operator in the short- and long-term.

Shock vibration is a more jarring and unpredictable vibration that may occur while driving over a rut or hole causing an immediate effect or injury in the short-term to the operator.

Harshness: The human perception of noise, or vibration, or a combination of the two, that cannot be measured directly in engineering units. Each person has his or her own opinion about harshness, although there are common threads to our likes and dislikes which influence our preferences for one product over another.

Hydraulic system

Eaton's Fluid Conveyance Noise, Vibration and Harshness Technology lab (Eaton FC NVH), Maumee, OH, is an integrated and custom solution to fully optimize noise and vibration reduction within any hydraulic system where the transfer of fluids is present.

The use of Eaton's FC NVH solution can be applied in applications which range from power steering lines, to hydraulic pumps, to active ride systems. Eaton has provided fluid conveyance solutions for two decades for automotive applications and is now applying similar techniques for heavy-duty applications.

Variations in fluid flow, or pressure ripples, are created by the pump. The ripples create energy fluctuations which pass through the fluid to the structural components and into the air as noise. "Whether it's fluid-borne or airborne, noise is still a wave," says Chris Schadewald, engineering director, Fluid Conveyance Div., Eaton Fluid Power - Hydraulics Business.

Eaton FC NVH utilizes a custom hose assembly that specifically targets the fluid borne noise to reduce overall noise levels without over attenuation. A special tuner cable is designed to match the specific dynamics of each machine.

Specially designed tuning cables allow energy from the pressure ripple to escape at the wave's peak, reducing the amount of energy transferred to the system, thus lowering the amount of airborne noise released. Eaton's software analyzes hydraulic system characteristics to optimize the noise reduction.

Eaton's FC NVH lab allows Kurt Steinberger, lead engineer - NVH, Eaton Fluid Power - Hydraulic Business, to test systems or machines on site and utilize Maumee's fluid conveyance prototyping capabilities, as well as its materials test lab, to diagnose the noise problem, design and create a unique system solution in one location.

"Due to the fact that there is no one-size-fits-all solution, the challenge is to work within the OEM's design parameters as it relates to product envelope size and system pressure," says Steinberger. The Eaton FC NVH team needs to work within the OEM's design parameters. Not only can Eaton provide the NVH solution to the customer, but the solution might also result in additional benefits which could include an increase in production throughput and a reduction in components and overall machine weight.

Eaton's capabilities allow the NVH technology team to find more proactive solutions to give OEMs a more off-the-shelf solution. Right now each solution is custom made, but with more research, common elements will emerge.

Complementing Eaton's FC NVH capabilities are an in-house hemi-anechoic chamber in Eden Prairie, MN, and proprietary software. These tools enable Eaton to diagnose overall sources of NVH, model the system and run simulations to find the optimal solutions, and present the results and options to the customer.

By reducing noise in the hydraulic system at its source, Eaton can offer benefits including operator safety/fatigue reduction, a competitive advantage in the market, and the elimination of alternative noise suppression devices such as a resonator, attenuator or accumulator, which lowers part numbers, assembly time and cost.