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DetroitTom · 05-02-2008, 09:50 AM

I worked in automotive noise and vibration for years. Here are some basic tips.

Quiet the exhaust and intake as much as you can first. Get the exhaust discharge & air intake away from the operator as much as possible. There are sophisticated ways to tune intake and exhausts, but volume works wonders in general.

There are three basic kinds of sound packaging.

An absorber is placed on a surface to keep sound from being reflected. Typically in a car this is on the engine side of the firewall and under the hood. Melamine foam would be good for a tractor. Thicker is better, spaced off the surface increases efficiency.

Damping is provided by heavy rubber or tar paper types of material. It works by mass loading a panel and turning vibration caused by sound waves into heat. Typically this is installed on floors and other panels that are between the operator and the sound source. The Dynamat is an example of a damping material.

The third kind of sound packaging is a barrier. This is basically a heavy, dense material separated from the sheet metal by a soft material like foam or felt. The high end stuff uses lead sheets sandwiched in foam. Typically these are used on the passenger side of the firewall and on the floor,with carpet fused to the top. The thicker the soft (decoupler) material, the more effective it is.

A final tip, sealing of the cab is all important for high frequency noise like diesel clatter and hydraulic squeals.

Good luck.

05-02-2008, 09:50 AM	#14 (permalink)
DetroitTom Silver Member Join Date: Sep 2002 Posts: 149	Re: What kind of foam for sound deadening I worked in automotive noise and vibration for years. Here are some basic tips. Quiet the exhaust and intake as much as you can first. Get the exhaust discharge & air intake away from the operator as much as possible. There are sophisticated ways to tune intake and exhausts, but volume works wonders in general. There are three basic kinds of sound packaging. An absorber is placed on a surface to keep sound from being reflected. Typically in a car this is on the engine side of the firewall and under the hood. Melamine foam would be good for a tractor. Thicker is better, spaced off the surface increases efficiency. Damping is provided by heavy rubber or tar paper types of material. It works by mass loading a panel and turning vibration caused by sound waves into heat. Typically this is installed on floors and other panels that are between the operator and the sound source. The Dynamat is an example of a damping material. The third kind of sound packaging is a barrier. This is basically a heavy, dense material separated from the sheet metal by a soft material like foam or felt. The high end stuff uses lead sheets sandwiched in foam. Typically these are used on the passenger side of the firewall and on the floor,with carpet fused to the top. The thicker the soft (decoupler) material, the more effective it is. A final tip, sealing of the cab is all important for high frequency noise like diesel clatter and hydraulic squeals. Good luck.