22-08-2013, 03:34 PM
Scotch Yoke Analysis
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INTRODUCTION
In this lab experiment you will be studying a scotch yoke mechanism that converts circular
motion into linear motion. One way of measuring velocity is by the use of a velocity transducer.
This laboratory apparatus consist of velocity transducer mounted to measure the linear velocity
of the scotch yoke mechanism. The goal is to calibrate the velocity transducer to measure
velocity.
Part I Equations of harmonic Motion
1. The displacement motion of the scotch yoke mechanism (Figure 1) produces a simple
harmonic motion which is defined as:
s(t) = so sin ωt
Measure the total travel for the scotch yoke mechanism. From the travel measurement,
calculate the maximum displacement value, so. Note: so can be and must be measured as 1⁄2
of the linear system travel.
2. Determine what the time-dependent equation for velocity is by differentiating the
displacement equation in 1. When does the maximum velocity occur and how can we
calculate the maximum velocity?
3. The frequency with which a process repeats itself is called cyclic frequency, f, and is typically
measured in cycles per second, or hertz (Hz). However, circular frequency is also useful in
studying cyclic relations. Circular frequency, ω, has units of radians per second (rad/sec).
The connection between the two stem from the fact that one cycle is equivalent to 2π radians
( ω =2 π f ). Determine a conversion factor for converting the period, T, to circular
frequency, ω. Determine a conversion for converting RPM to circular frequency, ω.