Question

5. Two helical torsion springs are used to counterbalance the weight of an overhead garage door. One spring is a right-hand spring, and the other is a left-hand spring. Each spring is made from standard oil-tempered steel with a diameter of d=0.225", has an outside diameter of D=1.78", and contains N=140 turns. The springs fit over a 1.0" diameter rotating shaft supported at three locations by bearings attached to the structure. A small wire rope is wound around each of the two end pulleys to support the weight of the door. The radius from the center of each pulley to the centerline of each rope is 2.5". The total length of wire rope excursion from the door-closed to the door-open position is 85". Determine a. The angular deflection of the springs (hint: determine number of shaft revolutions first) b. The maximum bending stress in the spring when the door is closed. c. What is the heaviest door that could be supported by the arrangement shown? $G_{max} = 190$ ksi (Hint: calculate the spring deflection from knowing how much the rope moves down)

          5. Two helical torsion springs are used to
counterbalance the weight of an overhead garage
door. One spring is a right-hand spring, and the
other is a left-hand spring. Each spring is made from
standard oil-tempered steel with a diameter of
d=0.225", has an outside diameter of D=1.78", and
contains N=140 turns. The springs fit over a 1.0"
diameter rotating shaft supported at three locations
by bearings attached to the structure. A small wire
rope is wound around each of the two end pulleys to
support the weight of the door. The radius from the
center of each pulley to the centerline of each rope
is 2.5". The total length of wire rope excursion from
the door-closed to the door-open position is 85". Determine
a. The angular deflection of the springs (hint: determine number of shaft revolutions first)
b. The maximum bending stress in the spring when the door is closed.
c. What is the heaviest door that could be supported by the arrangement shown?
$G_{max} = 190$ ksi (Hint: calculate the spring deflection from knowing how much the rope moves
down)

5. Two helical torsion springs are used to
counterbalance the weight of an overhead garage
door. One spring is a right-hand spring, and the
other is a left-hand spring. Each spring is made from
standard oil-tempered steel with a diameter of
d=0.225", has an outside diameter of D=1.78", and
contains N=140 turns. The springs fit over a 1.0"
diameter rotating shaft supported at three locations
by bearings attached to the structure. A small wire
rope is wound around each of the two end pulleys to
support the weight of the door. The radius from the
center of each pulley to the centerline of each rope
is 2.5". The total length of wire rope excursion from
the door-closed to the door-open position is 85". Determine
a. The angular deflection of the springs (hint: determine number of shaft revolutions first)
b. The maximum bending stress in the spring when the door is closed.
c. What is the heaviest door that could be supported by the arrangement shown?
Gmax = 190 ksi (Hint: calculate the spring deflection from knowing how much the rope moves
down)

Added by Kelly W.

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