Results
In order to make use of the analysis methods that were taught in class, the group needed to break this mechanism into two separate mechanisms and superimpose the solutions to from the input to the output.
The ram is mounted to ground at a 60 degree angle and serves as the lone input for our machine. Mounted with its slider and adjacent attachment to point {B and A} was the first mechanism needed to be analyzed and is determined to be a four-bar slider crank inverted to 60 degrees (Note: NOT an Inverted Slider Crank!). The “ground” link for the slider crank is rotated to sixty degrees from absolute ground to match the book equations for a slider crank. This was needed because the slider cranks solved for in class had constant offsets; without rotating the ground link for the slider crank, our offset would not be constant.
When looking at the picture, it is relevant that arm {AB} of our slider crank can also be analyzed as part of a pin-joined four-bar that is creating the needed output. Bar AB is the link that allows us to superimpose the ram input onto the lift output. Given a ram speed and acceleration, which was estimated from the total ram extension divided by an average lifting time, the group solved the slider crank for the kinematics of point B and transferred these results to the four-bar problem. Already having solved for theta2 and the position, velocity and acceleration of a point on “link 2”, it was relatively simple to solve for the output of the lift.
