Page 124 - Analysis and Design of Machine Elements

Analysis and Design of Machine Elements
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3 A coupling and gear is connected with a shaft by keys, as shown in Figure P4.6. The
shaft transmits a torque of T = 1000 N m, with slight impact. The shaft, gear and
coupling are made of medium carbon steel, cast steel and grey iron, respectively,
with corresponding allowable stresses of 120, 110 and 55 MPa, respectively. The shaft
diameters connecting the coupling and gear are d = 55 mm, d = 85 mm. The width
1
2
of the coupling and gear are L = 116 mm, L = 90 mm, respectively. Select the type
1
2
and dimension of keys and check their strength.

Figure P4.6 Illustration for Design Problem 3.

Structure Design Problems

1 To facilitate assembly and disassembly of a taper key, we usually fabricate a slope of
1 : 100 ___________.
(a) at the bottom of keyway on the shaft
(b) on the top side of key
(c) at the bottom of keyway on the hub
(d) both (b) and (c)

2 In a gear reducer shown in Figure P4.7, gears 2 and 3 are installed on the shaft II.
These two gears should be installed on _________.
Figure P4.7 Illustration for Structure Design Question 2.

(a) the two keys on the same generatrix
(b) thesamekey
∘
(c) the two keys located at an interval of 180 circumferentially
∘
(d) the two keys located at an interval of 120 circumferentially