Gear Trains

1
Example 3
Figure shows an epicyclic gear train with the
following specifications A and B has 40 and 80
teeth external and internal respectively. C and
D is a compound gear wheels has 20 and 50 teeth
external.
Dr.T.V.Govindaraju,SSEC
2
Example 3
E and F is a compound gear wheel has 20 and 40
teeth external. G has 90 teeth external. Gear
wheel A is fixed and the arm runs at 100 rpm in
clockwise direction. Determine the torque exerted
on the gear wheel G, if the input torque to the
arm is 1000 N-m.
Dr.T.V.Govindaraju,SSEC
3
Example 3
www.mekanizmalar.com
Dr.T.V.Govindaraju,SSEC
4
Example 3
Dr.T.V.Govindaraju,SSEC
5
Example 3
Dr.T.V.Govindaraju,SSEC
6
Example 3
When A is fixed m n 0 Arm rotates at 100
rpm n 100 rpm ? m -100 rpm
a)      Speed of compound gear wheel C
D -2m n 200 100
300 rpm (CW) b)      Speed of gear B
-½ m n -½
? -100 100 150 rpm (CW)
Dr.T.V.Govindaraju,SSEC
7
Example 3
c)      Speed of gear G

d)      Speed of compound gear wheel E F
5 ?
-100 100 - 400 rpm (CCW)  Input rate of work
Tarm ? ?arm and Output rate of work TG
? ?G Tarm ? ?arm TG ? ?G ?
1000 ? 100 TG ? 322.2
TG 310.36 N-m
Dr.T.V.Govindaraju,SSEC
8
Example 3-algebraic method
Speed of compound wheel C D
Dr.T.V.Govindaraju,SSEC
9
Example 3-algebraic method
Speed of compound wheel C D
Dr.T.V.Govindaraju,SSEC
10
Example 3-algebraic method
Speed of gear B
Dr.T.V.Govindaraju,SSEC
11
Example 3-algebraic method
Speed of gear B
Dr.T.V.Govindaraju,SSEC
12
Example 3-algebraic method
Speed of gear G
Dr.T.V.Govindaraju,SSEC
13
Example 3-algebraic method
Speed of gear G
Dr.T.V.Govindaraju,SSEC
14
Example 3-algebraic method
Speed of compound gear wheel E F
Dr.T.V.Govindaraju,SSEC
15
Example 4
In an epicyclic gear of sun and planet type
shown in figure, the pitch circle diameter of the
annular wheel A is to be nearly 216mm and module
4mm. When the annular ring is stationary, the
spider that carries three planet wheels P of
equal size to make one revolution for every five
revolution of the driving spindle carrying the
sun wheel.
Dr.T.V.Govindaraju,SSEC
16
Example 4
Determine the number of teeth for all the wheels
and the exact pitch circle diameter of the
annular wheel. If an input torque of 20 N-m is
applied to the spindle carrying the sun wheel,
determine the fixed torque on the annular wheel.
Dr.T.V.Govindaraju,SSEC
17
Example 4-Continued
Solution Module being the same for all the
meshing gears
tA tS 2tP
www.mekanizmalar.com
Dr.T.V.Govindaraju,SSEC
18
Example 4-Continued
Dr.T.V.Govindaraju,SSEC
19
Example 4-Continued
Dr.T.V.Govindaraju,SSEC
20
Example 4-Continued
Dr.T.V.Govindaraju,SSEC
21
Example 4-Continued
If L rotates 1 revolution ? n 1 (1) The
sun wheel S to rotate 5 revolutions
correspondingly ? n m 5 (2) From (1) and
(2) m 4 When A is fixed
Dr.T.V.Govindaraju,SSEC
22
Example 4-Continued
But fractional teeth are not possible therefore
tS should be either 13 or 14 and tA
correspondingly 52 and 56.
Trial 1 Let tA 52 and tS 13
Trial 2 Let tA 56 and tS 14
Dr.T.V.Govindaraju,SSEC
23
Example 4-Continued

• tA 56, tS 14 and tP 21
• ? PCD of A 56 ? 4 224 mm
• Also
• Torque on L ? ?L Torque on S ? ?S
• Torque on L ? ?L
• Fixing torque on A (tL tS) 100 20 80
  N-m

Dr.T.V.Govindaraju,SSEC
24
Example 4-Algebraic method
Dr.T.V.Govindaraju,SSEC
25
Example 4-Algebraic method
Dr.T.V.Govindaraju,SSEC
26
Example 4-Continued
But fractional teeth are not possible therefore
tS should be either 13 or 14 and tA
correspondingly 52 and 56.
Trial 1 Let tA 52 and tS 13
Trial 2 Let tA 56 and tS 14
Dr.T.V.Govindaraju,SSEC
27
Example 4-Continued

• tA 56, tS 14 and tP 21
• ? PCD of A 56 ? 4 224 mm
• Also
• Torque on L ? ?L Torque on S ? ?S
• Torque on L ? ?L
• Fixing torque on A (tL tS) 100 20 80
  N-m

Dr.T.V.Govindaraju,SSEC