PES INSTITUTE OF TECHNOLOGY BANGALORE – SOUTH CAMPUS
Hosur Road, (1K.M. Before Electronic City), Bangalore – 560 100
DEPARTMENT OF MECHANICAL ENGINEERING
SCHEME AND SOLUTION – II INTERNAL TEST
Subject
:KINEMATICS OF MACHINES
Semester: IV
Sub. Code
Name of the faculty
:10ME44
:VEERESH & AZHARUDDIN KAZI
Section: A & C
Q.No
1(A)
Marks
Explain with neat sketches types of gear trains.
Simple gear Train
The typical spur gears as shown in diagram. The direction of rotation is reversed from one gear
to another. It has no affect on the gear ratio. The teeth on the gears must all be the same size so
if gear A advances one tooth to B
Compound gear Train
Compound gears are simply a chain of simple gear trains with the input of the second being
the output of the first. A chain of two pairs is shown below. Gear B is the output of the first
pair and gear C is the input of the second pair. Gears B and C are locked to the same shaft and
revolve at the same speed. For large velocities ratios, compound gear train arrangement is
preferred.
Reverted Gear Train
The driver and driven axes lies on the same line. These are used in speed reducers, clocks and
machine
tools.
05
1(B)
05
Derive an expression for torque in an epicyclical gear train.
The energy equation is
MtiNi+MtoNo+MtfNf = 0
The torque equation is
Mti+Mto+Mtf = 0
Where
I = Input torque
O = Output Torque
F = Holding or fixing torque
Mti = 1000xPx60/2πNi
R
C-72
A-80
D-48
B-40
2
In the planetary reduction unit shown in fig ‘a’, gear 2 runs at 200rpm CW, Gears 3, 4 are
compound gears and is free to rotate on the arm A. Determine number of teeth on gear 1,
Speed and direction of rotation of gear 5 and arm A.
Given
T2 = 25, T3 = 35, T4 = 20, T5 = 40, T1=?
10
Internal Gear 1
3
4
1
ARM
2
5
T1 = 80
TV = -0.1785 Considering gears 1,2,3,4 and arm A
Na = 30.39 rpm CW
TV = 0.357 Considering gears 2,3,4,5 and arm A
N5 = 90.94 rpm CW
3
In the fig ‘b’ shown below Gears A, D, E are free to rotate on the axis P. The compound gear
BC rotate on axis Q at the end of the arm R, all the gears have equal pitch. The gears D, E are
internal gears. Gear A rotates at 90 rpm CCW and gear D rotates at 450 rpm CW. Find speed
and direction of arm R and gear E.
P
Q
Td = 84
Te = 108
x = -490.9
y = 400.9
E
D
A-18
B-45
C-21
Ne = 482.71 CW
10
4
An epicyclical gear train shown in fig ‘c’ consists of two sun wheels A & D with 80 and 48
teeth. The sun wheels are engaged with compound planet wheels B & C, the number of teeth
on gear C is 72. Find the speed and direction of wheel D when wheel A is fixed. The arm R
makes 200 rpm CW. If 2KW is transmitted by the arm, what is the torque required to hold the
sun wheel A.
R
10
C-72
A-80
D-48
B-40
Tb = 40
x = -200
Mtr = 95.49 N-m
5 (A)
Nd = -400 rpm
Mtd = 47.74 N-m
Classify Cams with neat
sketch
y = 200
Mta = -143.23 N-m
05
5 (B)
Draw the cam profile for following conditions:
Follower type = roller follower, off-set to the right by 5mm; lift = 30mm; base circle radius
=25mm; roller radius = 5mm; out stroke with SHM, for 1200 cam rotation; dwell for 600 cam
rotation; return stroke during 1200 cam rotation; first half of return stroke with Uniform
velocity and second half with UARM; dwell for the remaining period
15
6(A)
05
Classify Followers with neat sketch.
6(B)
Draw the cam profile for following conditions:
15
Follower type = roller follower, off set to the right of cam axis by 18mm; lift = 35mm; base
Circle radius = 50mm;roller radius = 14mm; out stroke with SHM in 0.05sec; dwell for
0.0125sec; return stroke with UARM, during 0.125sec;
dwell for the remaining period.
During return stroke, acceleration is 3/5 times retardation. Determine max. Velocity and
acceleration during out stroke and return stroke if the cam rotates at 240 rpm