test 1 mekanik mesin
DESCRIPTION
mekanik mesin test 1TRANSCRIPT
FAKULTI KEJURUTERAAN MEKANIKAL DAN PEMBUATAN
UNIVERSITI TUN HUSSEIN ONN MALAYSIA
BDA20303MECHANIC OF MACHINE
TEST 1 ( 2 Hour)
Q1 Figure Q1 shows a motor accelerating a hoist with diameter 0.9 m, through two sets of gear reducing system. The number of teeth on gear 1, gear 2, gear 3 and gear 4 are 100, 350, 100 and 450 respectively. Moment of inertia for the motor shaft is 5 kgm2, middle shaft is 20 kgm2 and hoist shaft is 100 kgm2. The rope that is encircled on the hoist must capable to accelerate up a load of M kg that is sliding on a 1 in 50 slope at acceleration of 3 m/s2. Friction on the slope is 1000N and the total torque at motor required to raise the load is 1500Nm. Gear efficiency of gear set 1-2 is 90% and gear efficiency for gear set 3-4 is 95% gear. The friction torque effect at the middle shaft is Nm and at the hoist shaft is Nm. Investigate the mass of the load at the above conditions.
Motor
Gear 1
Gear 2
Gear 3
Gear 4
Hoist
Load
Figure Q1
Q2 A pulley of 150 mm effective diameter running at 1500 rev/min drives a followers of 750 mm diameter, the two shafts being parallel, 1 m apart and the free parts of the belt considered straight. The belt has a mass of 0.4 kg/m and the maximum tension is to be 72 N. Estimate,
1. Maximum tension difference allowing for the inertia of the belt if μ = 0.4.
2. The speed of the driven pulley at the maximum condition and the power transmitted to it if the belt has a cross-section area of 320 mm² and E for the material is 300 MN/m².
Skema Jawapan
SOLUTION TO Q1
Total torque required by motor to raise load
where = Torque to overcome equivalent inertia (refer to motor side).
=Torque to accelerate the load through gear system
Total torque to overcome friction effect.
a) Consider for
For double set of gear reducing system,
1
1
1
1
1
kgm2
For the overall gear ratio,
From , thus, rad/s2
Also from gear ratio, , thus, rad/s2
Thus Nm
b) Consider for as in Figure 15;
2
1
1
1
1
1From
N
Thus, torque to accelerate hoist
Nm
Use gear efficiency to relate with
Nm
c) Consider for
Friction effect can be grouped together to form where;
Nm
RF Mg
1F
θ
Mg sinθ
r
F1
hoist
Figure 18: inclined loading
1
1
1
1
1
1
1
1
2
1
From
Thus kg
Solution Question 2
1
1
25