Brock Institute for
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Design notes
Continuous rotary motion input to intermittent
reciprocating linear motion output
These notes are intended to describe the design sequence and geometry underlying the class of mechanisms that convert continuous rotary input motion to an intermittent reciprocating linear motion such as the one animated at http://www.brockeng.com/mechanism/Intermittent.htm.
The mechanism has the following parts with dimensions as described. (Description or numerical values that are applicable to the example are shown in square brackets):
The design proceeds by the following steps:
Figure 1. Output vs. input profile.
Figure 2. Interface between input spoke and output
step.
and the geometry is specified in Figure 3.
Figure 3. Calculating radius, R, and step, S.
Given the stroke, L, and the ramp-up angle, U, the spoke radius, R, is determined. With spoke radius, R, and ramp-up angle, U, the frame step, S, is determined.
For a single input wheel with equal length spokes, the ramp-up angle, U, and the ramp-down angle, D, will be equal. As a result, the return step on the bottom of the frame will have the same geometry as the one at the top. If a more complex input / output profile is desired, it can be accommodated with correspondingly more complex mechanism arrangements.
Copyright 2003, Brock Engineering, Fred Klingener May be reproduced for personal use with this notice. |
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