Saving cost and time was a motivation to develop a mechanized harvesting system for chickpeas, which are manually uprooted on fallow fields in developing countries. A tractor-pulled harvester with a modified stripper header was designed and fabricated, in which passive fingers with V-shaped slots removes chickpea pods from anchored plant; batted reel sweeps the pods across the platform. Field experiments were conducted to determine the effect of slot width and reel speed on machine performance in terms of harvesting losses. Minimal losses were found when the design was configured with a slot width of 4 cm, reel speed of 50 rpm and reel kinematic index of 1.6. The prototype harvester with a 1 m working width produced the work rate of 0.18 ha h -1 and exhibited acceptable working quality. The main conclusion is that the modified stripper harvester can work in unevenness ground where other machines cannot operate.Additional key words: Cicer arietinum; losses; mechanized harvesting; performance; stripper header.* Corresponding author: h.golpira@uok.ac.ir Received: 01-08-12. Accepted: 14-11-13.Abbreviations used: D (reel diameter, m); H m (weight of removed pods with the stem, kg); H p (weight of harvested pods on the header, kg); L (total losses, %); L p (weight of remained pods on the plant, kg); L s (weight of shattered pods on the ground, kg); MOG (material other than grain); n (speed of the reel, rpm); v (forward speed, km h -1 ); V (peripheral speed of the reel km h -1 ); λ (reel kinematic index, dimensionless).

Interest in the development of stripper headers is growing owing to the excessive losses of combine harvesters and costs of manually harvesting for chickpeas. The design of a new concept can enhance the mechanized process for chickpea harvesting. A modified stripper platform was designed, in which passive fingers with V-shape slots remove the pods from the anchored plant. The floating platform was accompanied by a reel to complete the harvesting header. Black-box modeling was used to redesign the functional operators of the header followed by an investigation of the system behavior. Physical models of the platform and reel were modified to determine the crucial variables of the header arrangement during field trials. The slot width was fixed at 40 mm, finger length at 40 mm, keyhole diameter at 10 mm and entrance width at 6 mm; the batted reel at peripheral diameter of 700 mm and speed at 50 rpm. A tractormounted experimental harvester was built to evaluate the work quality of the stripper header. The performance of the prototype was tested with respect to losses and results confirmed the efficiency of the modified stripper header for chickpea harvesting. Furthermore, the header with a 1.4 m working width produced the spot work rates of 0.42 ha h -1 . Additional key words: black-box modeling; chickpea harvesting; design; losses; stripper header. Abbreviations used: MOG (material other than grain); p.t.o. (power take-off). Nomenclature: D (reel diameter, m); n (speed of the reel, rpm); n w (speed of the ground wheel, rpm); T (number of tooth on reel gear); T w (number of tooth on ground gear); v (forward speed, km h -1 ); V (peripheral speed of the reel, km h -1 ); W dp (weight of detached pods on the header, kg); W pg (weight of detached pods on the ground, kg); W ud (weight of remained pods on the plant, kg); Ï (reel kinematic index, dimensionless).

Aim of study: This paper presents a mathematical modeling approach to redesign the reels of chickpea harvesters for harvest efficiency.Area of study: A prototype chickpea harvester was designed and evaluated on the Dooshan farm of the University of Kurdistan, Sanandaj, Iran.Material and methods: The strategy used for reducing harvesting losses derived from the dynamic study of the reel applied to the chickpea harvester. The machine was designed such that bats of a power take-off (PTO)-powered reel, in conjunction with passive fingers, harvest pods from anchored plants and throw the pods into a hopper. The trochoid trajectory of the reel bats concerning reel kinematic index, and plant height and spacing was determined for redesigning the reel.Main results: This kinematic design allowed an estimation of the reel orientation at the time of impact. The experimentally validated model offers an accurate and low computational cost method to redesign harvester reels.Research highlights: The new chickpea harvester implemented with a four fixed-bat reel, a height of 40 cm above the ground for the reel axis, and featuring a kinematic index of 2.4 was capable of harvesting pods with harvesting efficiency of over 70%; a significant improvement in harvesting performance.

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