Unformatted text preview: The wheels B and C are compound and rotate together on a
pin carried at the end of arm E. The wheel D has internal
teeth and is fixed to the outer casing of the block so that it
does not rotate.
The wheels A and B have 16 and 36 teeth respectively with a
module of 3 mm. The wheels C and D have a module of 4
mm. Find : 1. the number of teeth on wheels C and D when
the speed of A is ten times the speed of arm E, both rotating
in the same sense, and 2. the speed of wheel D when the
wheel A i s fixed and the arm E r otates at 450 r.p.m.
[Ans. TC = 13 ; TD = 52 ; 500 r.p.m. anticlockwise] Fig. 13.39 11. A compound epicyclic gear is shown diagrammatically in Fig. 13.40. The gears A , D and E are free to
rotate on the axis P. The compound gear B and C rotate together on the axis Q at the end of arm F. All
the gears have equal pitch. The number of external teeth on the gears A , B and C are 18, 45 and 21
respectively. The gears D and E are annular gears. The gear A rotates at 100 r.p.m. in the anticlockwise
direction and the gear D rotates at 450 r.p.m. clockwise. Find the speed and direction of the arm and
the gear E.
[Ans. 400 r.p.m. clockwise ; 483.3 r.p.m. clockwise] 12. In an epicyclic gear train of the ‘sun and planet type’ as shown in Fig. 13.41, the pitch circle diameter
of the internally toothed ring D is to be 216 mm and the module 4 mm. When the ring D is stationary,
the spider A , which carries three planet wheels C of equal size, is to make one revolution in the same
sense as the sun wheel B for every five revolutions of the driving spindle carrying the sunwheel B .
Determine suitable number of teeth for all the wheels and the exact diameter of pitch circle of the ring.
[Ans. TB = 14 , TC = 21 , TD = 56 ; 224 mm] Fig. 13.40
13. Fig. 13.41 An epicyclic train is shown in Fig. 13.42. Internal gear A is keyed to the driving shaft and has 30 teeth.
Compound wheel C and D of 20 and 22 teeth respectively are free to rotate on the pin fixed to the arm
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- Fall '08
- gear, Gear Trains, Epicyclic gearing, epicyclic gear train