Unformatted text preview: eel increases, by the same amount. This may be well understood by
drawing the table of motions as follows :
* This difficulty does not arise with the front wheels as they are greatly used for steering purposes and are
mounted on separate axles and can run freely at different speeds. 459 l Chapter 13 : Gear Trains
Table 13.17. Table of motions.
Revolutions of elements
Step No.
1. Conditions of motion Gear B Gear C Gear B fixedGear C rotated
through + 1 revolution (i.e.
1 revolution anticlockwise ) 0 Gear E +1 + Gear D TC
TE – TC TE
×
= –1
TE TD (3 TC = TD )
TC
TE 2. Gear B fixedGear C rotated
through + x revolutions 0 +x 3. Add + y revolutions to all
elements +y +y +y 4. Total motion +y x +y y + x× +x × –x
+y TC
TE y–x From the table, we see that when the gear B , which derives motion from the engine shaft,
rotates at y revolutions, then the speed of inner gear D (or the rear axle Q) is less than y by x revolutions and the speed of the outer gear C (or the rear axle P) is greater than y by x revolutions. In other
words, the two parts of the rear axle and thus the two wheels rotate at two different speeds. We also
see from the table that the speed of gear B is the mean of speeds of the gears C and D.
Example 13.16. Two bevel gears A and B (having 40 teeth and 30 teeth) are rigidly mounted
on two coaxial shafts X and Y. A bevel gear C (having
50 teeth) meshes with A and B and rotates freely on one
end of an arm. At the other end of the arm is welded a
sleeve and the sleeve is riding freely loose on the axes of
the shafts X and Y. Sketch the arrangement.
If the shaft X rotates at 100 r.p.m. clockwise and
arm rotates at 100 r.p.m.anitclockwise, find the
speed of shaft Y.
Solution. Given : T A = 40 ; T B = 30 ; T C = 50 ; N X
= N A = 100 r.p.m. (clockwise) ; Speed of arm = 100 r.p.m.
(anticlockwise)
The arangement is shown in Fig. 13.22.
The table of motions is drawn as below :
Fig. 13.22
Table 13.18. Table of motions.
Revolutions of elements
Step No. Conditions of moti...
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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
 CELGHORN

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