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PROBLEM 8.75
The ends of two fixed rods A and B are each made in the form of a single-threaded screw of mean radius
6 mm and pitch 2 mm. Rod A has a right-handed thread and rod B has a left-handed thread. The
coefficient of static friction between the rods and the threaded sleeve is 0.12. Determine the magnitude of
the couple that must be applied to the sleeve in order to draw the rods closer together.
PROBLEM 8.76
Assuming that in Problem 8.75 a right-handed thread is used on both rods A and B, determine the
magnitude of the couple that must be applied to the sleeve in order to rotate it.
PROBLEM 8.75
The ends of two fixed rods A and B are each made in the form of a single-threaded
screw of mean radius 6 mm and pitch 2 mm. Rod A has a right-handed thread and rod B has a left-handed
thread. The coefficient of static friction between the rods and the threaded sleeve is 0.12. Determine the
magnitude of the couple that must be applied to the sleeve in order to draw the rods closer together.
PROBLEM 8.77
A lever of negligible weight is loosely fitted onto a 75-mm-
diameter fixed shaft. It is observed that the lever will just start
rotating if a 3-kg mass is added at C. Determine the
coefficient of static friction between the shaft and the lever.
Copyright © McGraw-Hill Education. Permission required for reproduction or display.
PROBLEM 8.78
A hot-metal ladle and its contents weigh 130 kips. Knowing that the
coefficient of static friction between the hooks and the pinion is 0.30,
determine the tension in cable AB required to start tipping the ladle.
PROBLEM 8.79
The double pulley shown is attached to a 10-mm-radius shaft
that fits loosely in a fixed bearing. Knowing that the coefficient
of static friction between the shaft and the poorly lubricated
bearing is 0.40, determine the magnitude of the force
P
required
to start raising the load.
PROBLEM 8.80
The double pulley shown is attached to a 10-mm-radius shaft
that fits loosely in a fixed bearing. Knowing that the coefficient
of static friction between the shaft and the poorly lubricated
bearing is 0.40, determine the magnitude of the force
P
required
to start raising the load.
PROBLEM 8.81
The double pulley shown is attached to a 10-mm-radius shaft
that fits loosely in a fixed bearing. Knowing that the coefficient
of static friction between the shaft and the poorly lubricated
bearing is 0.40, determine the magnitude of the smallest force
P
required to maintain equilibrium.
PROBLEM 8.82
The double pulley shown is attached to a 10-mm-radius shaft
that fits loosely in a fixed bearing. Knowing that the coefficient
of static friction between the shaft and the poorly lubricated
bearing is 0.40, determine the magnitude of the smallest force
P
required to maintain equilibrium.
PROBLEM 8.83
The block and tackle shown are used to raise a 150-lb load. Each of the 3-in.-
diameter pulleys rotates on a 0.5-in.-diameter axle. Knowing that the coefficient
of static friction is 0.20, determine the tension in each portion of the rope as the
load is slowly raised.
PROBLEM 8.84
The block and tackle shown are used to lower a 150-lb load. Each of the 3-in.-
diameter pulleys rotates on a 0.5-in.-diameter axle. Knowing that the coefficient
of static friction is 0.20, determine the tension in each portion of the rope as the
load is slowly lowered.
