(a) Stopping
Distances, Type B Safeties.
(1) The following
formulas shall be used to determine the maximum and minimum stopping distances
for Type B car and counterweight safeties:
S = (V)2/81,144 +
0.84
S' = (V)2/231,840
Where:
S = Maximum stopping distance in feet.
S' = Minimum stopping distance in feet.
V = Governor tripping speed in feet per
minute.
(2) Figures 3106 A1
to 3106 A7 show the maximum and minimum stopping distances from various
governor tripping speeds.
Design Data and Formulas
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Stopping Distances for Type B Car and
Counterweight Safeties
FIG. 3106 A-1
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Stopping Distance in Feet Stopping Distances for
Type B Car and Counterweight Safeties
FIG. 3106 A-2
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FIG. 3106 A-3
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FIG. 3106 A-4
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FIG. 3106 A-5
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FIG. 3106 A-6
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FIG. 3106 A-7
(b) Data Required for Approval.
(1) Two complete sets of assembly and detail
drawings of the safety device shall be submitted to the division and shall show
the following:
(A) The construction of the
safety device and the dimensions of major parts for identification.
(B) The adjustment range and valves of the
data as marked on the safety marking plate required by Section
3035(n).
(C) The design and operational details
indicating that the safety device complies with Sections
3035(g),
3035(i),
3035(j),
3035(k),
3035 (
l), 3035(o),
and 3035(p).
(2) The
results of performance tests conducted by the manufacturer or an approved
testing laboratory. These tests shall be conducted to demonstrate that the
safety device will function satisfactorily within the range of loads and speeds
for which the safety is to be approved.
(c) Performance Tests Required for Safety
Approval.
(1) On Type B safeties in which the
maximum retarding force does not depend on the pull in the governor rope, the
tests shall be of the drop-test type or of the overspeed type. On such tests
the governor tripping speed need not exceed 280 feet per minute.
(2) On Type B safeties in which the maximum
retarding force depends on the pull in the governor rope and the car speed at
which the safety is applied, the tests shall be of the drop-test
type.
(3) On Type A safeties the
tests shall be:
(A) A test shall be made of
the inertia application of the safety by attaching the proper weight, as
determined by the manufacturer, to the return run of the governor rope. This
weight shall be that necessary to reproduce inertia operation of the safety at
not to exceed
9/10
gravity. The inertia application shall be made with the car stationary, and the
weight when released shall move the safety pats into contact with the rails,
and
(B) A runaway test made from
governor tripping speed with the safety device applied by the governor
mechanism.
(4) On Type C
safeties, the tests shall be of the overspeed type. The inertia application of
the safety is not required.
(d) Factor of Safety. Parts of safeties,
except springs, shall have a factor of safety of not less than 3.5, and the
materials used shall have an elongation of not less than 15 percent in a length
of 2 inches. Forged, cast, or welded parts shall be stress relieved.
EXCEPTION: Safety-rope drums, leading sheaves, and
their supporting brackets and safety jaw gibs may be made of cast iron and
other metals, provided such parts have a factor of safety of not less than
10.
(1) Rope used as a connection from
the safety to the governor rope, including rope wound on the safety rope drum,
shall be not less than 3/8 inch in diameter and shall be made of a
corrosion-resistant metal. Tiller rope construction shall not be used. The
factor of safety of the rope shall be not less than 5.
(2) The factors of safety shall be based upon
the maximum stresses developed in the parts during the operation of the safety
when stopping rated load from governor tripping speed.
(3) Springs may be used in the operation of
car or counterweights safeties. Where used, and where partially loaded prior to
safety operation, the loading on the spring shall not produce a fiber stress
exceeding ½ the elastic limit of the material. During operation of the
safety, the fiber stress shall not exceed 85 percent of the elastic limit of
the material. Helical springs, where used, shall be in compression.
(4) Safety-rope leading-sheave brackets and
other safety operating parts shall not be attached to or supported by wood
platform members.