General · EdgepediaSeptember 17, 20267 min read

Reaper

A reaper is an agricultural machine that cuts standing grain crops, replacing the hand sickle with a powered blade that moves back and forth through the stalks while the machine advances across the field, severing plants in a continuous swath.¹

Key fact	Detail
Function	Cuts grain stalks with a reciprocating cutter bar as the machine moves through the crop, replacing hand sickle harvesting¹
Earliest practical machine	Patrick Bell's reaping machine, made 1827-1828 in Scotland, believed to be the first practical mechanical reaper²
First US patents	Obed Hussey patented a reaper in 1833; Cyrus McCormick's patent followed in 1834³
Bell's output	Two horses pushing from behind; cut on average one acre per hour²
Field capacity today	A self-propelled reaper in Nepal harvested 0.13 ha/h at 68.69% field efficiency, against 0.0084 ha/h for sickle harvesting⁴
Cost advantage	A small-farm reaper in Iran cost $20/ha to operate against $154/ha for manual harvesting⁵
Quality standard	The Philippine rice reaper standard requires at least 65% field efficiency and no more than 1.5% total machine loss⁶

How a reaper works

At its most basic, a reaper serves as a substitute for the hand sickle: as the machine travels forward, a mechanical blade swings back and forth through the stalks, cutting the plants in an unbroken swath.¹ The late-nineteenth-century McCormick "Daisy" self-rake reaper illustrates the classic layout: an operator sat on a seat mounted on the left wheel axle driving two horses or mules, a reciprocal cutter bar more than five feet long carried three triangular sickle blades oscillating through guard teeth, and three rotating arms with three-inch projections raked the cut grain into gavels, which still had to be hand-tied rather than bound and shocked by the machine.⁷^•¹⁵

Two features of the earliest machines persist in modern combine harvesters. Patrick Bell devised a rotating reel with paddles to gather the crop into the cutting mechanism, and a set of reciprocating blades that shear the stems with a scissor-like side-to-side motion.²

Early development

Patrick Bell. The Reverend Patrick Bell of Forfarshire, Scotland, designed his machine in the mid-1820s; the surviving example is dated 1827-1828 and is believed to be the first practical mechanical reaper.² The crop was collected by a revolving reel onto an inclined apron that delivered the corn at the sides of the machine. It was designed for a single horse, but one horse proved inadequate, and it was modified for two horses walking behind and pushing the machine through collars harnessed to a pole, cutting on average one acre per hour.² Only a small number were built, and the extent of Bell's influence has been controversial; four were exported to the USA before 1831, the year Cyrus McCormick introduced a more commercially successful machine. Bell received belated recognition: in 1867, two years before his death, the Highland and Agricultural Society of Scotland awarded him a £1000 prize.²

Hussey and McCormick. Obed Hussey and Cyrus McCormick were rivals for the honor of developing the first successful grain harvester in the United States. Hussey, of Baltimore, Maryland, patented a reaper in 1833 and had sold about 500 machines by 1850; McCormick's patent was 1834.³ During the first four years of the rivalry Hussey was the commercial winner by default, since McCormick withheld his machine from the marketplace while he made the numerous modifications needed to make it work well under most conceivable harvest conditions; McCormick himself later said he did not sell his first machine until 1839.⁸

McCormick's commercial success. McCormick was born in Virginia in 1809 and patented the reaper in 1834; his machine harvested up to fifteen acres of wheat a day, against three acres cut by hand.⁹ In 1847 he built a reaper factory in Chicago on Water Street next to the Chicago River; by the following year the business that became the McCormick Harvesting Machine Company had made seven hundred machines, by 1850 the number had more than doubled, and by 1868 ten thousand reapers were made annually.⁹ In 1851 American reapers from McCormick and Hussey created a stir at the Great Exhibition in London and helped promote the acceptance of reapers in Britain.² In 1902 the McCormick company merged with the Deering Harvester Company and three other rivals to form the International Harvester Company.⁹

Refinements. The reaper was improved steadily. In the 1850s self-rake reapers eliminated the workers needed to rake the platform where stalks fell; in the 1870s a binder was added to tie sheaves and drop them on the ground; and from the 1920s tractors pulled reapers and binders.⁹ The 1895 Daisy self-rake shows the change in crew size: McCormick's earlier "Old Reliable" model had required two men, one raking grain from the apron as the reaper drove along, while the Daisy eliminated the second operator.⁷

Modern reapers

Reapers remain in use where combine harvesters are uneconomic, particularly small, irregular, or wet paddy fields in Asia. Designs include self-propelled walking-type machines, power-tiller-mounted reapers, and reaper-cum-binders that also tie the cut crop into bundles.¹⁰

Measured performance. A Chinese walking-type self-propelled reaper tested in Lalitpur, Nepal, achieved an average effective field capacity of 0.13 ha/h with 68.69% field efficiency at an operating speed of 1.72 km/h, while sickle harvesting managed 0.0084 ha/h.⁴ In Chhattisgarh, India, a self-propelled reaper-cum-binder with a 1400 mm cutter bar operated at 2.5 km/h reached a field capacity of 0.28-0.32 ha/h, about 44 times the traditional manual method, and saved 2223 to 2464 Rs/ha over local and improved sickles on rice; bundling was unsatisfactory in soybean, producing 21% grain loss.¹¹ In Iran, a reaper designed for small and rough fields, with a 1 m cutter bar and a 6.5 hp engine, ran best at a forward speed of 0.5 m/s, which gave the lowest crop losses; its total operating cost was $20/ha against $154/ha for manual harvesting, and the minimum justified ownership area was 1.3 ha.⁵

Standards and known problems. The Philippine standard for rice reapers, PNS/PAES 212:2015, sets minimum field efficiency at 65%, maximum header loss at 0.5%, maximum conveying loss at 1.0%, maximum total machine loss at 1.5%, and a maximum noise level of 92 dB(A); cutting elements must be carbon tool steel in the AISI 1080 to 1085 range with a case-hardened serrated portion.⁶ Surveys of reaper users in Bangladesh rank the leading problems as lack of repair and maintenance facilities, inability to repair in local workshops, wheel problems, and transportation difficulty, with excessive vibration and noise of the star wheel the top functional complaints.¹² In hilly Himachal Pradesh, a power-tiller-operated reaper performed well in large plots but was not found feasible for small, irregular plots under 150 m².¹³

Relation to the combine harvester

A reaper performs only the cutting step, leaving threshing to a separate stationary thresher; in comparative trials of wheat harvesting in Bihar, India, the semi-mechanized option paired a tractor-mounted reaper-cum-binder with a 1.37 m working width and a stationary thresher, while the fully mechanized option used a self-propelled combine with a 3.6 m working width.¹⁴ The reaper's core mechanisms, the rotating reel and the reciprocating cutter bar, carry through from Bell's 1820s machine into modern combines.²

References

Initially written Sep 17, 2026 · Reviewed: Sep 30, 2026; Oct 21, 2026 · Edited: Oct 15, 2026; Oct 21, 2026