The main purpose of this study is to develop the grain-conveying unit to the
grain tank of Fiat combine harvester. The modified grain conveying unit was proposed
to avoid the continues wearing in the transmission bevel gearbox of distribution auger
and grain elevator. to increase the combine field capacity and to improve overall
efficiency of the combine. The grain-conveying unit includes elevator, bevel gearbox and grain
distribution auger. The grain-conveying unit 0 f Fiat combine was developed in this
study on two stages, the first stage was to change the fixing place of grain elevator
and distribution auger with respect to the grain tank. While, the second stage was to
change the transmission bevel gearbox between distribution auger and grain elevator
by two sprocket wheels and chain. The development was carried out in a private
workshop in Mansoura City. The field experiments were conducted at different far-ms
in Dakhalia Governorate during the wheat harvesting seasons of 2002 and 2003.
Harvesting of Sakha 93 wheat variety was carried out using the Fiat combine
harvester before and after development taking place. The total losses, field capacity
and efficiency, combine performance efficiency and criterion harvesting cost as a
function of change in drum speed, grain moisture content and reel index were
considered. Development of grain conveying unit of the grain tank of Fiat combine
harvester decreased the total grain losses by about 1.8-4% and the total grain
damage (visible and invisible) by about 15-30% compared with its results before
development. Using the developed combine improved overall performance efficiency
and recorded the maximum values of effective field capacity and efficiency (3.03
fed.lh and 76.4%, respectively) compared with the performance of un-developed
combine (2.88 fed.lh and 63.9 %, respectively) at forward speed of 4.5 km/h. The
minimum value of criterion cost (120.89LE/fed.) was recorded with the developed
combine at drum speed of 30.2 mIs, reel index 1 :1.3 and grain moisture content of
20.2% compared with 126.87 LE/fed for the un-developed combine under the same
previous conditions.