Friday, October 25, 2019
hand tools :: essays research papers
Hand Tools and Devices Ergonomically oriented hand tool design: Maintain a straight wrist     Maintain a straight wrist      Bent Nose Pliers. Such tools permit grasping, cutting, or turning objects while the wrist remains in a relatively straight position.          Hammer With Deviated Handle. The slightly bent handle maintains a straight wrist during the final impact position. Maintain a straight wrist     Maintain a straight wrist      Soldering Iron. The perpendicular bend of the head permits application of heat to a distal object while avoiding deviation of the wrist.          Saws, Power Wrench, Knife. A perpendicular handle (pistol grip) maintains a straight wrist during cutting, sawing, or rotary operations such as drilling or nut tightening. Maintain a straight wrist     Provide an optimal grip span      Cylindrical Handle. A tool for rotary action on a horizontal work piece maintain the wrist in a straight position.          Excessive grip span does not allow optimal application of force and imposes undue stress upon the joints. Avoid tissue compression     Protect against heat, cold, vibration extremes      Excessively thin or short handles cause small surface areas which in turn cause excessive pressure on tissues, leading to loss of local circulation.     Circulation is also affected by other factors such as vibration and temperature extremes from the tool of from the immediate environment. Gloves and insulating materials are used as protective devices. Second handle     Expanding spring An additional handle for powered tools, located near the front end, helps support a heavy tool, resistance to excessive torque, and safe placement of the tool on to the work piece.           Expanding spring on handles opens handles without stressful operator effort. Thumb stop     Gloves      A thumb stop improves stability, increases thrust force, and avoids slippage.     Gloves may be unavoidably used in inclement circumstances. Compensations must be made, when gloves are used, for a diminished grip force, diminished manual dexterity, and increased bulkiness which requires large handle dimensions. General considerations     Loss of grip      The functional assignment of the hands. Hands, when used with a tool, may be classified into the holding hand and the assisting hand.          Dropped Tool. Power saw dropped on foot. Loss of grip     Loss of grip      Slipping Hazard. Hand slips on to unguarded surface.          Curved Knife Guard. Loss of grip     Loss of grip      Knife. Ring guard. Enclosure for one finger.          Knife. Handle guard. Enclosure for all fingers. Balanced power tool     Second handle      Handle located at center of gravity.          A second handle near the front of a large tool allows added control. A second handle will also aid in resisting high torque forces. Crushing in between     Accidental activation      Handle Stops. Handle stops allowing at least 2.5 cm clearance prevent crushing fingers between handles.
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