Abstract

Tractor operator comfort is affected by how much noise tractor produces during continuous operation. Noise at work in agriculture or horticulture can cause hearing loss. A tractor without cabin and one with cabin (closed window and open window) loaded with mounted moldboard plow and disk harrow were tested for noise level in different gears at the driver's ear and bystander ear. The permissible exposure time for safe hearing effect was calculated. The sound level trend versus gears was also shown. Results showed that the Sound Pressure Level (SPL) at the driver ear for the tractor without cab in all gears ranging from a low of 91 dB(A) to a high of 93 dB(A) were more than National Institute for Occupational Safety and Health (NIOSH) allowable 85 dB(A) criteria for eight hour of operation. All domestically manufactured in Iran are without cabin. The SPL of the tractor with open windows cab with a range of 86 to 88 dB(A) was also higher than the standards, but lower than that for the tractor without cab. Loading with moldboard and disk did show significant effect at Hi 1 gear for no cabin and open window cabin. The SPL for closed cabin in all cases stayed below 82 dB(A). It was concluded that the driver should either stay on driving for less than 2 h with tractors without cabin and open window cabin or the only best way, the tractors should be equipped with factory made cabins. Using some kind of ear protection is another alternative. Even with the cabin type of tractors, drivers should avoid opening the window very often for say checking the operation of the machinery behind the tractor or in case the air conditioner malfunctions. Using some kind ear protection can be used for the safety but this may increase farm related injuries. Therefore it is recommended that homemade tractors are to be equipped with factory made cabins.

Key word: Sound pressure level (SPL), tractors, cabin, gears, driver's ear and bystander ear, loaded.