Gear - 1
N1 = 65
LAB 4, PROBLEM # 7: ALARM CLOCK GEAR TRAIN
A. First goal is to find ω9 / ω1. You MUST follow the gear path; gear 1 to 2 to 3...
Gear - 2
N2 = 12
When gears are on separate shafts (I.e between gears 1 and 2):
= (Nb / Na)
Ni = # of teeth on gear i
ωa / ωb
Gear - 3
N3 = 60
When gears are on the same shaft (I.e. between gears 2 and 3):
ωa = ωb
Gear - 4
N4 = 8
Gear - 5
N5 = 64
B. Second goal is to find the torque ratio (Τ9 / Τ1) using power flow.
You can relate the power between gears 1 and 9 directly! You do not have to go through each gear as you did above.
ηm x PIN
ηm x T1 x ω1
=
=
Gear - 6
N6 = 8
Gear - 7
N7 = 56
POUT=
T9 x ω9
To Hour Hand
To Minute Hand
Gear train receives
energy/power from spring
Timing mechanism
regulates speed of
gear 9 which then
regulates the speed
of gear 1 via the
gear train.
9
4
3
1
Gear - 8
N8 = 7
2
Spring Container
7
Gear - 9
N9 = 15
8
5
To Alarm Striker
6
Wind to input energy: E = T(θ) dθ
For our rough estimate, we assumed T was near constant so E ~ T ∆θ
This energy is stored in the spring