Page 47 - Cam Design Handbook

THB2 8/15/03 12:48 PM Page 35

BASIC CURVES 35

Jerk, y''' = • Jerk, y''' = •

Displacement, y
Dwell
y, y', y", y''' Velocity, y'
C

5 D h

3
1
A Cam angle q b
Dwell
Jerk, y''' = • Acceleration, y"

FIGURE 2.4. Constant acceleration curve—DRD cam.

substituting in Eq. (2.12)
2 h
C =
b 2

2 h
displacement y = q 2 (2.17)
b 2
4 h
velocity y ¢ = q (2.18)
b 2
4 h
acceleration y ¢¢ = = a constant (2.19)
b 2
jerk y¢≤ = 0 except at dwell ends and the midpoint

b
££ b
q
2
In the other half of the curve (negative acceleration), the displacement is
q
y = C + C + C q 2 (2.20)
2
1
0