Script 39.5


Groundnuts, or peanuts, are one of the major cash crops in some regions of Thailand and are an important source of protein for rural people. Thousands of Thai farmers work farms of less than one hectare of land, producing groundnuts by manual methods. This is a

labour‑intensive process which, along with the low productivity of the land and the low quality of the nuts, results in a low income for farmers.

Traditional groundnut cultivation requires substantial time for land and seed preparation, planting, cultivating, and harvesting, as well as drying, dehusking, and cleaning the nuts before selling.

Mechanized equipment developed in Thailand to modernize peanut farming is now being introduced in Africa, Indonesia, and the Philippines. The manual peanut sheller benefits farmers by reducing the time it takes to shell the nuts. Shelling the nuts by hand produces 7‑l0 kilograms of shelled nuts per day, whereas the sheller has a capacity of 30‑60 kilograms of shelled nuts per hour. It can increase farmers’ incomes as shelled nuts bring in twice as much as unshelled nuts. The initial investment can be recovered quickly, often within the first year of commercial shelling.

The peanut sheller is made of a used rubber tire mounted in a metal housing with a concave wire screen bottom. As the wheel is cranked, the nuts enter the space between the tire and the screen, are dehulled, and drop through the screen into a trough. Winnowing can be done by hand or with a fan. The sheller is 95% efficient and only 3‑5% of the nuts are broken. It requires very little maintenance. The average cost per year for maintenance is US $3 to $5. Spare parts are easily available. During trials, a single machine processed 22 tonnes of nuts in one season without any repairs.

A less expensive version of the sheller has also been designed. It has a simpler and smaller frame and no trough. The nuts fall through the screen directly to the ground below. Its capacity is 25‑30 kilograms per hour and it has the same efficiency as the larger version. As well, a motorized rubber‑tire sheller with an integrated winnowing fan has been designed for use by large‑scale farmers, co‑ops, and local traders.

Cost and availability
The sheller costs approximately US $110 for the manual version and US $450 to $500 for the motorized version. The sheller is available from the following manufacturer:

Kunasin Manufacturing, l07‑l08 Sri‑Satchanalai Road, Sawankalok, Sukhothai, Thailand. Tel.: (055) 642ll9.


This article was published with the aid of a grant from the International Development Research Centre (IDRC), Ottawa, Canada. It is adapted from 101 Technologies from the South for the South, 1992, IDRC, P.O. Box 8500, Ottawa, Canada K1G 3H9.

Information Sources

Dr. Winit Chinsuwan Vice‑President, Research Affairs Khon Kaen University Khon Kaen 40002, Thailand Tel.: (66‑043) 237604; Telex: 55303 UNIKHON TH.

Resources and publications

The following resources are available from Dr. Chinsuwan, Khon Kaen University, Khon Kaen 40002, Thailand:

Construction Handbook for Groundnut Machinery, booklet in Thai and English with engineering drawings. Includes instructions for building the manual sheller as well as other groundnut equipment such as a stripper/winnower, a motorized peanut sheller, a grinder, and two types of planters.

Machinery for Groundnuts, leaflet. Available in Thai and English.

A 20‑minute promotional video covers the range of groundnut equipment developed at Khon Kaen University.  Available in English or Thai, PAL standard.