This standard outlines the specifications for processed timber intended for use in lorry body construction in India. It details approved wood species, dimensional criteria, moisture thresholds, permissible defects, and necessary preservative treatments to guarantee strength and longevity. It serves as a critical reference for manufacturers, engineers, and quality inspectors engaged in timber procurement and preparation for commercial vehicle bodies.
Overview
This standard outlines the specifications for processed timber intended for use in lorry body construction in India. It details approved wood species, dimensional criteria, moisture thresholds, permissible defects, and necessary preservative treatments to guarantee strength and longevity. It serves as a critical reference for manufacturers, engineers, and quality inspectors engaged in timber procurement and preparation for commercial vehicle bodies.
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Contents
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Frequently Asked
IS 2179 (1979) specifies a list of approved timber species categorized by component for lorry body fabrication. For cross-bearers and longitudinal runners, species include Aini (Artocarpus hirsutus), Bijasal (Pterocarpus marsupium), Deodar (Cedrus deodara), Hathipaila (Pterospermum acerifolium), Kala-siris (Albizia odoratissima), Kokko (Albizia lebbeck), Mundani (Acrocarpus fraxinifolius), Padri (Stereospermum spp.), Safed-siris (Albizia procera), Sissoo (Dalbergia sissoo), Teak (Tectona grandis), and Thingan (Hopea odorata). For body sides, floors, front, and tailboards, consult Appendix A of the standard for detailed species recommendations.
According to IS 2179, the moisture content limits for converted timber depend on thickness and climatic zone. Timber with thickness of 50 mm or more should have moisture content between 10% and 16% measured within 20 mm from the surface. Timber less than 50 mm thick should range between 8% and 14%. In humid or rainy areas such as Assam and Malabar, an additional tolerance of +3% moisture content is permitted, aligning with zone definitions in IS 287-1973 to ensure durability and dimensional stability.
Timber used in lorry bodies must be free from major defects like centre-heart (pith), decay, shakes, spike or slay knots, spiral or twisted grain, twist, and active insect damage. Permissible defects are limited to minor, non-structural flaws as defined in Clause 7 of IS 2179. Surface cracks within specified depths (depending on timber thickness) are allowed on surfaces excluding the ends. Minor sound knots are acceptable if within size and spacing limits, ensuring structural integrity is not compromised.
IS 2179 mandates that timber containing sapwood must undergo pressure treatment with approved preservatives as per IS 401-1967. Prophylactic treatments are required for species marked in Appendix A to protect against decay and insect attack. Seasoning as per IS 1141-1973 is also compulsory. Additionally, timber ends should be coated with materials such as thick coal tar, bituminous paint, rosin and lamp black mixture, hardened gloss oil, paraffin wax, molasses and lime, or specialized anti-splitting preservatives to prevent moisture ingress and prolong service life.
The dimensions of timber planks and scantlings are to be provided as ordered by the purchaser, with IS 2179 not prescribing fixed sizes. Moisture content must be controlled within specified limits: 10% to 16% for thicknesses 50 mm and above, and 8% to 14% for thinner pieces. Knot tolerances are specified allowing live knots up to 10 mm freely, and 10 to 35 mm knots if spaced at least 30 cm apart with a maximum of two knots per meter. Dead knots up to 6 mm are allowed freely, with 6 to 25 mm under similar conditions as live knots. These measures ensure structural performance and reliability.
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