Meriam, Kraige & Bolton — Analysis of Structures: Problem 6_117

⚡ Mecademy AIENG정역학 · ch6  Problem Statement The design of the cam-lock vise provides a quick positive clamping action with a friction coefficient between the cam and the movable jaw A of 0.30. (a) As the cam and lever are rotating clockwise approaching the locking position shown with P = 30 lb, determine the clamping force C. (b) With P removed, find the friction force F in the locking position. (c) Determine the force P', opposite from P, required to release the clamp. Problem 6/117 (a) Clamping force C To determine the clamping force , we analyze the equilibrium of the cam as it rotates clockwise. Let the pivot be the origin . Based on the geometry provided in the diagram, the contact point between the cam and the movable jaw is located at and (above the centerline to ensure locking occurs during clockwise rotation). 1. Formula: Sum of moments about pivot : where is the moment of force , is the moment of the normal reaction force (which equals clamping force ), and is the moment of the friction force . 2. Substitution: Moment of : (Clockwise is negative). Moment of normal force : The jaw is to the left, so it exerts a normal force on the cam in the direction. At , this force creates a clockwise moment: . Moment of friction force : For clockwise rotation ( is clockwise), the velocity of the cam at contact point is . The vertical component is upward, so the friction force from the jaw on the cam acts downward: . C O(0,0) KAx= −2 in.y=0.5 in. O M = ∑ O M + P M + N M = F f 0