3. A gear train is a combination
of gears used to transmit
motion and power from one
shaft to another
It is also known as train of
toothed wheels
Gear trains may use spur,
bevel or spiral gears.
4. Used to either speed up or stepped
down the speed of driven shaft and
follower.
Examples :- 1) Automobile
2) Clocks
3) Ships
4) Watches
5) Lathe Machines etc.
7. As gear A drives gear B .
Gear C is rigidly mounted on gear on the
axis of gear B so speed will be same.
Gear C drives the gear D
8. 1) For gear A and B :
NB ∕ NA = tA ∕ tB = dA ∕ dB….(1)
2) For gear C and D :
ND ∕ NC = tC ∕ tD = dC ∕ dD…(2)
Multiplying (1) and (2)
NB ∕ NA × ND ∕ NC = tA ∕ tB × tC ∕ tD
= dA ∕ dB × dC ∕
dD
9. But NB = NC (Since gear B and C are fixed
on same shaft )
Therefore,
Velocity ratio, ND∕ NA= tA ∕ tB × tC ∕ tD
= dA ∕ dB × dC ∕
dD
10. ND∕ NA=
Product of number of teeth on drivers
Product of number of teeth on followers
ND∕ NA =
Product of diameters of drivers
Product of diameters of followers
11. 1) Higher and lower velocity ratio can be
obtained .
2) Velocity ratio for the given distance
between driving and driven shaft can be
obtained.
12. Kenneth J. Waldron, Gary L. Kizel,
Kinematics, Dynamics and Design of
Machinery ,Second Edition, 2010