Motion Transformation Systems The mechanical fxn of relaying

Motion Transformation Systems The mechanical fxn of relaying a motion from 1 part to another while altering the nature of the motion.

5 Systems 1) Rack and Pinion Systems 2) Screw Gear Systems Type 1 3) Screw Gear Systems Type 2 4) Cam and Follower Systems 5) Slider-Crank Mechanisms

Rack and Pinion Systems Rotation to Translation or Translation to Rotation Reversible

Rack and Pinion • • • at least 1 gear = a pinion 1 straight bar with teeth = rack teeth on rack and pinion must be identical frequent lubrication the greater the # of teeth the slower the rotation

Rack and Pinion Animation http: //www. youtube. com/watch? v=D 3 Mr. Ungdl CQ

Screw Gear Systems Type 1 • the screw is the driver • rotational is transformed into translational • e. g. jacks for lifting cars

Screw Gear Type 1 Scissor Car Jack http: //www. youtube. com/watch? v= Qe. B 2 Yx. Mqog. I

Screw Gear Systems Type 2 • the nut is the driver • rotational to translational • e. g. pipe wrenches

Screw Gear Type 2 Pipe Wrench http: //www. youtube. com/watch? v=HYspwt. CZ 1 yo

Screw Gear Systems • type 1 (car jack) has the nut connected to the screw so that the nut cannot rotate • in both systems the threads of the screws and nuts must match • type 2 (monkey wrench) has the nut fixed so that its only possible motion is rotational

Cam and Follower Systems • transform the rotational motion of a cam into the recriprocating translational motion of a follower • a back and forth movement like that of a sewing machine • cams = rotational axis is centred • eccentric cams = rotational axis is off-centre

Cam and Follower • the follower must be guided in its translational motion • the shape of the cam determines how the follower will move • a device such as a return spring is usually necessary to keep the follower in continual contact with the cam

Cam and follower http: //www. youtube. com/watch? v=Zbds. Gf_t 8 h s

Slider-Crank Mechanisms • used in internal combustion engine • to transform the translational motion of the pistons into the rotational motion of the crank

Slider - Crank Mechanisms • the connecting rod contains 2 bushings to attach it to the crank and piston • the cylinder must guide the part moving in translation • frequent lubrication

Slider - Crank Mechanisms http: //www. youtube. com/watch? v=Kn. ASJHtb. G B 0