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Unformatted text preview: r Clutch
C. It may be noted that when the
annulus gear is fixed, the sun gear
Sun and Planet gears.
provides the drive and when the
sun gear is fixed, the annulus gear
provides the drive. In both cases, the arm acts as a follower. Oil
Gears Input Sun
Flange Note : The gear at the centre is called the sun gear and the gears whose axes move are called planet gears. Fig. 13.9. Compound epicyclic gear train. Chapter 13 : Gear Trains l 443 Let T A , T B , T C , and T D be the teeth and N A, N B, N C and N D be the speeds for the gears A , B ,
C and D respectively. A little consideration will show that when the arm is fixed and the sun gear D is
turned anticlockwise, then the compound gear B -C and the annulus gear A will rotate in the clockwise
The motion of rotations of the various elements are shown in the table below.
Table 13.4. Table of motions.
Revolutions of elements
No. Conditions of motion Arm Gear D Compound gear
B-C 1. Arm fixed-gear D rotates
through + 1 revolution 0 +1 – TD
TC – 2. Arm fixed-gear D rotates
through + x revolutions 0 +x – x× TD
TC –x × 3. Add + y revolutions to all
elements +y +y +y 4. Total motion +y x +y y–x× Gear A TD TB
TC TA TD TB
TC y –x× TD TB
TC TA Note : If the annulus gear A is rotated through one revolution anticlockwise with the arm fixed, then the
compound gear rotates through T A / T B revolutions in the same sense and the sun gear D rotates through
T A / T B × T C / T D revolutions in clockwise direction. Example 13.6. An epicyclic gear consists of three gears A, B and C as shown in Fig. 13.10.
The gear A has 72 internal teeth and gear C has 32 external teeth. The gear B meshes with both A
and C and is carried on an arm EF which rotates about the centre of A at 18 r.p.m.. If the gear A is
fixed, determine the speed of gears B and C.
Solution. Given : T A = 72 ; T C = 32 ; Speed of arm EF = 18 r.p.m.
Considering the relative motion of rotation as shown in Table 13....
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This note was uploaded on 02/13/2014 for the course MIE 301 taught by Professor Celghorn during the Fall '08 term at University of Toronto.
- Fall '08