34 Pa. Code § 7.283 - Safety requirements
(a)
Slack cable device. A slack cable device shall be used in
connection with all power-driven freight elevator machinery of the winding drum
type which will automatically shut off the power, apply the brake, and stop the
machinery if the car is obstructed in its descent. The device shall be so
designed and installed that, after functioning, the mere resetting of the
device is not sufficient to move the elevator car unless the operator is in the
car and starts it in the normal manner.
(b)
Shaftway limit switches.
Direct connected drum-type elevators shall be equipped with upper and lower
final limit switches regardless of car travel or speed. All other electric
freight elevators having magnetic brakes shall be provided with upper and lower
final limit switches, except traction type with a speed of less than 125 feet
per minute. Final limit switches shall automatically cut off the current, apply
the brake and stop the machinery, and may be located in the shaftway with a cam
on the car or on the car with cams in the shaftway. When necessary because of
flood conditions, lower shaftway limit switches may be actuated by the
counterweight at the top of the shaftway. All cams actuating limit switches
shall be of metal. A stopping switch may also be mounted on the elevator car in
addition to limit switches in the shaftway, and so arranged as to be actuated
by stationary inclines placed in the shaftway at the upper and lower limits of
travel. A sequence relay shall be installed in connection with final limit and
direction switches of all electric rope control freight elevators, so connected
as to require the centering of the controlling mechanism before the elevator
car may be placed in operation. Friction-type governors without cable clamp
dogs are not permitted.
(c)
Automatic terminal stops. Automatic terminal stops shall be
provided on the machines of all power-driven freight elevators of the winding
drum type. Such devices shall operate independently of the car controlling
mechanism.
(d)
Brakes. Power-driven freight elevators, except hydraulic
elevators, shall be equipped with an effective brake which automatically
engages when the controlling mechanism of the elevator car is in a "stop"
position. Electric brakes are required in all existing elevators where electric
interlocks are installed. In such instances the requirements of subsection (b),
and §§
7.285(b) and
7.292(d)
(relating to control apparatus; and electric freight elevators) shall be met.
When a direct current elevator motor or motors derive current from an
alternating current power source through a nonrotating rectifying unit, means
shall be provided to absorb a sufficient amount of energy regenerated by the
motor or motors under overhauling load conditions to prevent any elevator from
attaining at any time, or under any conditions of load, more than 120 % of the
contract speed of the elevator. When a single rectifier is installed to supply
power for a number of elevators, or elevators in conjunction with other
electrical equipment in the building, separate means for absorbing the
generated power shall be installed for each elevator and other equipment in the
building shall not be depended upon for the absorption of this power.
(e)
Car safeties. Car
safeties are required in conformance with the following:
(1)
New installations. New
power-driven freight elevator cars suspended from cables shall be provided with
car safeties located under the car floors. Such safeties shall be capable of
stopping or holding the elevator car at any point of its travel. Freight
elevators having a speed of 100 feet per minute or less shall be provided with
car safeties actuated by a centrifugal speed governor, except when the car
travel does not exceed 20 feet, in which case car safeties of the spring grip
or broken rope type may be used. When the speed exceeds 100 feet per minute,
regardless of car travel, the car shall be provided with car safeties of the
friction clamp or other approved type, actuated by a centrifugal speed governor
in such a manner as to bring the elevator car to a gradual stop within a
distance of approximately 8 feet. A rack and pawl are not acceptable as a car
safety device. Tiller rope construction shall not be used for governor cables
except when used for the portion of the cable wound on the safety drum.
Governor cables shall be of iron or steel, monel metal, phosphor bronze or
equivalent, and shall not be less than 3/8 inch in diameter. The size, material
and construction of the governor rope, and the proper tripping speed of the
governor, shall be stamped on the governor stand or on a brass plate attached
to it in letters not less than 1/4 inch in height.
(2)
Existing installations.
When no car safeties are provided, they shall be installed in accordance with
the requirements for new installations. Existing car safeties may remain in
their present position if they are, upon being tested, found to be reliable.
Otherwise, they shall be replaced by new car safeties in accordance with the
requirements for new installations. A rack and pawl is not acceptable as a car
safety device. Whenever necessary to renew governor ropes or cables, such
renewals shall conform to the requirements for new construction.
(f)
Signs-riders.
Power-driven freight elevators shall have signs posted at every
landing and in the elevator car prohibiting all persons, except the operator
and not more than three designated assistants from riding on such car. See also
§
7.12(d) (relating
to rules of operation).
(g)
Illumination. The landings of all freight elevators shall be
adequately illuminated at all times when the building is in use so that the
entrance to the elevator car can be readily observed.
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