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PROBLEM 8.121
A cable is placed around three parallel pipes. Two of the pipes are
fixed and do not rotate; the third pipe is slowly rotated. Knowing
that the coefficients of friction are
0.25
s
and
0.20,
k
determine the largest weight W that can be raised (a) if only pipe
A is rotated counterclockwise, (b) if only pipe C is rotated
clockwise.
PROBLEM 8.122
A cable is placed around three parallel pipes. Knowing that the
coefficients of friction are
0.25
s
and
0.20,
k
determine
(a) the smallest weight W for which equilibrium is maintained,
(b) the largest weight W that can be raised if pipe B is slowly
rotated counterclockwise while pipes A and C remain fixed.
PROBLEM 8.123
A cable is placed around three parallel pipes. Two of the pipes are
fixed and do not rotate; the third pipe is slowly rotated. Knowing
that the coefficients of friction are
0.25
s
and
0.20,
k
determine the largest weight W that can be raised (a) if only pipe A
is rotated counterclockwise, (b) if only pipe C is rotated clockwise.
PROBLEM 8.124
A recording tape passes over the 20-mm-radius drive drum B and
under the idler drum C. Knowing that the coefficients of friction
between the tape and the drums are
0.40
s
and
0.30
k
and
that drum C is free to rotate, determine the smallest allowable value
of P if slipping of the tape on drum B is not to occur.
PROBLEM 8.125
Solve Problem 8.124 assuming that the idler drum C is frozen and
cannot rotate.
PROBLEM 8.124 A recording tape passes over the 20-mm-radius
drive drum B and under the idler drum C. Knowing that the
coefficients of friction between the tape and the drums are
0.40
s
and
0.30
k
and that drum C is free to rotate,
determine the smallest allowable value of P if slipping of the tape
on drum B is not to occur.
PROBLEM 8.126
The strap wrench shown is used to grip the pipe firmly without marring the external surface of the pipe.
Knowing that the coefficient of static friction is the same for all surfaces of contact, determine the
smallest value of
s
for which the wrench will be self-locking when
200 mm, 30 mm,ar
and
65 .
PROBLEM 8.126 (Continued)
PROBLEM 8.126 (Continued)
PROBLEM 8.127
Solve Problem 8.126 assuming that
75 .
PROBLEM 8.126 The strap wrench shown is used to grip the pipe firmly without marring the external
surface of the pipe. Knowing that the coefficient of static friction is the same for all surfaces of contact,
determine the smallest value of
s
for which the wrench will be self-locking when
200 mm, 30 mm,ar
and
65 .
tan
a
FDE r
PROBLEM 8.127 (Continued)
