For an assembly line, you need to design a linkage that moves a point P in approximately a straight line over a distance of 24” in one second. It is also specified that P must return from the endpoint back to the starting point in five seconds, giving a total cycle time of six seconds. The 24” section must be as straight as possible and the speed of P may not vary more than 5% during this part of the cycle when the crank is driven at a constant speed.
Read the section “Designing Optimum Straight-Line Fourbar Linkages” design a Hoeken-type linkage for these performance specifications.
1. Provide the link lengths (L1, L2, L3, L4) in inches and show clearly how you determined these.
2. What is the average velocity of P over the 24” path, in inches per second?
3. What is the maximum deviation in velocity ( v), in inches per second, over ? the 24” section of the path?
4. What is the maximum deviation (in inches) of P from the straight line?
5. What must be the speed of the motor that drives the crank, in RPM (revolutions per minute)?
6. Draw the linkage to scale, preferably in the position where P is at the beginning of the 24” section. Indicate dimensions of the linkage in your drawing. If you are not sure how to draw the assembled linkage,. If you wish to use a CAD package to assemble and draw your mechanism, that is fine too.