11-CS-2 Engineering Communications · December 2015
Question 2 of 7: Cumulative Trauma Disorders and Machine Guarding
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
Notes on this paper
National Exams — December 2015 — 11-CS-2 Engineering in Society: Health and Safety. Closed book; approved calculator permitted. Any five of the seven questions constitute a complete paper; all questions are of equal value. Answers are written in point form but fully, as instructed. Complete answers to all seven questions follow.
Musculoskeletal injuries that develop gradually from repeated micro-trauma to muscles, tendons, nerves and joints (no single event).
Risk factors: high repetition, forceful exertions, awkward/static postures, contact stress, vibration, cold—especially combined over long durations.
Symptoms progress from discomfort/fatigue to pain, numbness, weakness and loss of function (hands, wrists, arms, shoulders, back).
(ii) Typical Disorders
(a) Trigger finger — inflammation/thickening of a flexor tendon/sheath so the finger catches and snaps when straightened; from repeated gripping.
(b) Carpal tunnel syndrome — compression of the median nerve at the wrist from swollen tendons; numbness, tingling, pain and weakness in the thumb/first fingers.
(c) Tenosynovitis — inflammation of a tendon and its synovial sheath (pain, swelling, restricted movement) from repeated/forceful tendon motion.
(iii) Basic Principles of Machine Guarding
Prevent contact with the danger zone; be secure and durable (not easily removed/defeated); create no new hazard; not interfere with the work; allow maintenance without full removal; and interlock where appropriate (machine stops if guard opened), backed by lockout/tagout for servicing.
