How does A MECHANISM work Kinematic pairs 运动副 三守告 May roll afike.oe rollalie.depsmnditz on Sictioe iint-1or2Dor GURI 3-3 ME357 Design Manufacturing Il How does A MECHANISM work ©A joint is a movable connection between two or more links (at their nodes),which allows some motions,or potential motions between the connected links. Higher pairs高副 Lower pairs低副 GURE 3-3 6
6 ME357 Design & Manufacturing II How does A MECHANISM work Kinematic pairs 运动副 How does A MECHANISM work A joint is a movable connection between two or more links (at their nodes), which allows some motions, or potential motions between the connected links. Higher pairs 高副 Lower pairs 低副
How does A MECHANISM work Lower Pairs square X-section Revolute (R)joint-1 DOF Prismatic (P)joint-1 DOF Helical (H)joint-1 DOF 铰链副 移动副△9 螺旋副 Ar △y +40 Cylindric (C)joint-2 DOF Spherical (S)joint-3 DOF 柱销副 球铰副 %"罩省3pof FIGURE 2-3 (a)The six lower pairs Prismatic Revolute Cylindric Spherical Helical Planar(F) DOF How does A MECHANISM work Higher Pairs-1 Names Typical form Degree of Comments freedom Roller rotates about this line at this Cylindrical instant in its motion.Roller does not slip on the surface on which it roller rolls. Cam rolls and slides on follower. Cam pair Spur gears.helical gears.and other gears.(rolls slides) Gear pair 7
7 Prismatic Revolute Cylindric Spherical Helical Planar (F) DOF 1 1 2 3 1 3 Lower Pairs How does A MECHANISM work 铰链副 移动副 螺旋副 柱销副 球铰副 平面副 Higher Pairs-1 How does A MECHANISM work
Higher Pairs-2 Names Typical form Degree of Comments freedom Ball rolls without slipping. Rolling ball Ball can rotate about any axis Ball in through its center and slides along cylinder axis. cylinder Body can rotate about any axis Spatial point through the contact point and slide in any direction in the tangent contact plane. Planar VS Spatial Close VS Open In a planar mechanism,all of A spherical mechanism is one the relative motions of the rigid in which each link has some bodies are in one plane or in point that remain stationary as parallel planes. the linkage moves and in which the stationary points of all links lie at a common location 8
8 Higher Pairs-2 Planar VS Spatial Close VS Open In a planar mechanism, all of the relative motions of the rigid bodies are in one plane or in parallel planes. A spherical mechanism is one in which each link has some point that remain stationary as the linkage moves and in which the stationary points of all links lie at a common location