AbstractThe failure of spring bolt in front leaf spring dump truck unit was investigated. Root cause of spring bolt fracture was determined from fracture surface, and condition of spring bolt. The failure of spring bolt was caused by torsional shear. The load that been caused fracture is single-overload. Supporting factors of failure were caused by no lubrication, road condition, and unit load. Position of failure was happened in groove and close by threads, because that area possess a high stress concentration. Keywords: spring bolt, fracture surface, torsional shear, single-overload AbstrakPenyebab kegagalan spring bolt pada front leaf spring unit dump truck telah dilakukan investigasi. Penyebab patahan spring bolt ditentukan berdasarkan bentuk permukaan patahan (fracture surface), dan kondisi spring bolt. Spring bolt mengalami perpatahan yang disebabkan adanya torsional shear. Pembebanan yang telah menyebabkan perpatahan adalah pembebanan secara single-overload. Faktor-faktor penunjang patahan dikarenakan tidak adanya pelumasan, kondisi jalan, dan muatan unit. Posisi patahan terjadi di groove dan dekat ulir karena bagian tersebut memiliki konsentrasi tegangan yang tinggi. Kata kunci: spring bolt, fracture surface, torsional shear, single-overload
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