scholarly journals Discussion: “Design of Drag-Link Mechanisms With Minimax Transmission Angle Deviation” (Tsai, L.-W., 1983, ASME J. Mech. Transm. Autom. Des., 105, pp. 686–690)

1983 ◽  
Vol 105 (4) ◽  
pp. 691-691
Author(s):  
F. Freudenstein
Keyword(s):  
Transmission Angle ◽  
Angle Deviation ◽  
Drag Link

Design of Drag-Link Mechanisms With Minimax Transmission Angle Deviation

1983 ◽  
Vol 105 (4) ◽  
pp. 686-690 ◽  
Author(s):  
L.-W. Tsai
Keyword(s):  
Optimum Design ◽  
Design Criterion ◽  
Parameter Design ◽  
Cubic Equation ◽  
Design Charts ◽  
Link Mechanism ◽  
Transmission Angle ◽  
Angle Deviation ◽  
Drag Link ◽  
Maximum Transmission

In this paper, the design equations are derived for the synthesis of a drag-link mechanism, with given output-link rotation and the corresponding input-link rotation. The design criterion used is based on the maximum capability of a drag-link mechanism to provide a given delay or advance in the output motion. The solutions are given as a single-valued parametric set of equations for the link lengths. The transmission-angle optimization is accomplished by the minimization of the maximum transmission-angle deviation from 90 deg. It is shown that the optimum design can be obtained by solving a cubic equation in a single parameter. Design charts for the optimum design of a drag-link mechanism were developed. It is also shown that there is a one-to-one correspondence between the design of a crank-and-rocker mechanism and the drag-link mechanism.

On the Derivation of Grashof-Type Moveability Conditions With Transmission Angle Control for Spatial Mechanisms

1987 ◽  
Author(s):  
J. Rastegar
Keyword(s):  
Approximation Techniques ◽  
Link Type ◽  
Revolute Joints ◽  
Spatial Mechanisms ◽  
Transmission Angle ◽  
Full Rotation ◽  
Drag Link

Abstract Derivation of Grashof-type conditions for spatial mechanisms that may include transmission angle limitations are discussed. It is shown that in general, different conditions need to be derived for each one of the existing configurations of the mechanism. In the absence of any transmission angle control, the conditions would be identical for pairs of configurations. As an example, for RRRSR mechanisms, Grashof-type conditions that ensure crank rotatability, the existence of a drag link type of mechanism, single or multiple changeover points, the possibility of full rotation at intermediate revolute joints, etc., are determined. A general discussion of the problems involved in such derivations, the use of approximation techniques to overcome some of the problems, and several other related subjects are presented.

Design of Centric Drag-Link Mechanisms for Delay Generation With Focus on Space Occupation

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
Abdullah F. Al-Dwairi
Keyword(s):  
Length Ratio ◽  
Link Length ◽  
Link Mechanism ◽  
Maximum Delay ◽  
Transmission Angle ◽  
Quality Of Motion ◽  
Nonuniform Rotation ◽  
Drag Link ◽  
Space Occupation

Planar drag-link mechanism is a Grashofian four-bar chain with the shortest link fixed. In practice, the mechanism is used as a coupling between two shafts to convert uniform rotation of the driving shaft into a nonuniform rotation of the driven shaft. The nonuniformity in rotation is characterized by a cyclically increasing and decreasing delay (or advance) in the displacement of the driven shaft relative to that of the driving shaft. Drag-link synthesis problems include synthesizing the mechanism to generate a specified maximum delay. In a drag-link mechanism, the longer links make a full rotation about fixed pivots, which results in a relatively large installation space. This calls for designing drag-link mechanisms with a focus on space occupation, along with the traditional criteria of quality of motion transmission. Using position analysis, we investigate the relationships among mechanism space occupation, extreme transmission angle, and the generated maximum delay. Space occupation is represented by the link-length ratio of input link to fixed link. Given a desired maximum delay, the proposed approach suggests finding a unique extreme transmission angle value for which this link-length ratio is at a minimum. A closed-form solution to drag-link synthesis to generate a specified maximum delay is developed based on a compromise between quality of motion transmission and space occupation. For any drag-link designed by this compromise, the coupler link and the output crank are of the same length. Based on the obtained design equations, a graphical design solution and a method for evaluating space occupation are provided.

Design of Drag-Link Mechanisms With Optimum Transmission Angle

1983 ◽  
Vol 105 (2) ◽  
pp. 254-258 ◽  
Author(s):  
Lung-Wen Tsai
Keyword(s):  
Extreme Values ◽  
Angular Displacement ◽  
Output Link ◽  
Link Length ◽  
Design Charts ◽  
Link Mechanism ◽  
Transmission Angle ◽  
New Criterion ◽  
Four Bar Linkage ◽  
Drag Link

In this paper, a new criterion for the design of a drag-link mechanism with optimum transmission angle is established. The transmission angle, the angle between the coupler link and output link of a four-bar linkage, is considered to be optimized when its extreme values deviate equally from 90 deg. Based on this criterion, design equations and design charts are developed. It is shown that the optimum drag-link mechanism is a turning-block linkage. It is also shown that to displace the drag-link mechanism with optimum transmission angle from its minimum lag to its maximum lag position, the input link must always rotate 180 deg and the corresponding angular displacement of the output link depends only on the link-length ratio of the output link to the fixed-link.

On the Derivation of Grashof-Type Movability Conditions With Transmission Angle Limitations for Spatial Mechanisms

1989 ◽  
Vol 111 (4) ◽  
pp. 519-523 ◽  
Author(s):  
J. Rastegar
Keyword(s):  
Approximation Techniques ◽  
Link Type ◽  
Revolute Joints ◽  
Spatial Mechanisms ◽  
Transmission Angle ◽  
Full Rotation ◽  
Drag Link

Derivation of Grashof-type movability conditions for spatial mechanisms that may include transmission angle limitations is discussed. It is shown that in general, different conditions must be derived for each configuration (branch) of a mechanism. In the absence of transmission angle limitations, the conditions become identical for pairs of configurations. As an example, Grashof-type conditions that ensure crank rotatability, existence of drag link type of mechanisms, the presence of single or multiple changeover points, and the possibility of full rotation at intermediate revolute joints are derived for a spatial RRRSR mechanism. The problems involved in such derivations, the use of approximation techniques, and a number of related subjects are discussed.

The Design of the Spherical Drag-Link Mechanism

1967 ◽  
Vol 89 (1) ◽  
pp. 177-181 ◽  
Author(s):  
A. H. Soni ◽  
L. Harrisberger
Keyword(s):  
Design Chart ◽  
Link Mechanism ◽  
Transmission Angle ◽  
Drag Link

The spherical drag-link mechanism has been designed using an approach based on minimum transmission angle. Explicit relationships have been derived for the required dimensions which satisfy the criteria of minimum transmission angle, and a design chart for the solution of spherical drag-link mechanisms (similar to that of Hain) is presented. Also, the seven cognates of the spherical drag-link mechanisms are identified and discussed.

Geometrically Approximated Grashof-Type Movability Conditions for Spatial RSRC Mechanisms With Transmission Angle Limitations

1989 ◽  
Author(s):  
J. Rastegar ◽  
Q. Tu
Keyword(s):  
Closed Loop ◽  
The Other ◽  
Transmission Angle ◽  
Presence And Absence ◽  
Drag Link

Abstract For closed-loop spatial RSRC mechanisms, Grashof-type movability conditions (i.e., conditions for the existence of crank-rocker and drag link types of mechanisms) are derived using geometrical approximation. The movability conditions are derived in the presence and absence of transmission angle limitations. The mechanism has two branches (configurations). Without transmission angle limitations, both configurations have identical movability conditions. However, by including transmission angle limitations, the movability conditions become different for each configuration of the mechanism. The movability conditions eliminate the possibility of changeover from one configuration to the other.

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