Question

Consider the following statements about radial cams:

Which of the statements given above is/are correct?

• A. 1 only
• B. 2 only
• C. Both 1 and 2
• D. Neither 1 nor 2

Answer 1

The correct option is D Neither 1 nor 2

(i) Prime circle is the circle which is tangent to pitch curve.

While drawing pitch curve a circle of radius equal to sum of the radius of base circle and roller radius is drawn.

$\therefore \text{Prime circle radius = base circle radius + roller radius}$

$T_p=r_b+r_r$

Base circle is the circle on which cam profile is generated i.e. it has minimum radius and it is tangent to cam profile.

(ii) If the axis of follower passes through the cam centre (pivot) then it is called radial cam

h = displacement of follower

$V_f=\text{velocity of follower along follower axis}$

$V_s=\text{sliding velocity tangent to the cam}$


$\tan \theta =\frac{V_f}{(r_b+r+h)\omega }=\frac{\frac{dh}{dt}}{(r_b+r+h)\frac{d\theta }{dt}}$

$=\frac{\left(\frac{dh}{d\theta }\right)}{(r_b+r+h)}=\frac{\frac{dh}{d\theta }}{r_b+r+h}$

During complete rotation of cam, pressure angle doesn't remain constant. It varies with

$=\frac{\left(\frac{dh}{d\theta }\right)}{r_b+r+h}$