Introduction Mechanical systems Mechanical Systems This presentation describes

Introduction Mechanical systems Mechanical Systems This presentation describes some of the fundamental components and definitions of mechanical systems and mechanisms such as: 1. Links or bodies 2. Kinematic joints (pin, sliding, pin-sliding) 3. Open and closed chains 4. Commonly used mechanisms P. Nikravesh, AME, U of A

Pin and sliding joints Mechanical systems Pin and sliding joints link 1 A mechanical system consists of links (bodies) connected by joints. In this course all links are assumed non deformable (rigid). We mostly use two types of joints: Revolute (pin) joint ► link 2 Sliding joint: ► link 3 link 4 P. Nikravesh, AME, U of A

Pin-sliding joint Mechanical systems link 5 Pin-sliding joint Two links of a mechanical system may be connected by a combined pin-sliding joint. The joint provides rotational motion as a pin joint. ► It also provides sliding motion. ► And it also provides both rotational and sliding motions simultaneously. ► P. Nikravesh, AME, U of A link 6

Open and closed chains Mechanical systems can be categorized into open chains, closed chains, or combinations of open and closed chains. open chain example closed chain example P. Nikravesh, AME, U of A

Closed chains (mechanisms) Mechanical systems Closed chain systems A system may have one or more closed chains (loops). By definition a mechanism contains only closed chains. single loop mechanism double loop mechanism P. Nikravesh, AME, U of A

Commonly used mechanisms Mechanical systems Commonly used mechanisms Four-bar: A four-bar is a mechanism that consists of four links connected by four pin joints. Usually only three of the links are allowed to move. The links are numbered clockwise with the nonmoving link being link 1. Slider crank: A slider crank (or crank-slider) is a mechanism that consists of four links connected by three pin joints and one sliding joint. Usually only three of the links are allowed to move. The links are numbered clockwise with the nonmoving link being link 1. P. Nikravesh, AME, U of A O 2 link 1 O 4