held and fixed discs keyed to the stationary or housing member (pressure between the
discs being applied axially).
(5) "Brake - self-energizing band type." An essentially unidirectional brake in which
the holding effect is obtained by the snubbing action of a flexible band wrapped about a
cylindrical wheel or drum affixed to the rotating member to be held, the connections and
linkages being so arranged that the motion of the brake wheel or drum will act to increase
the tension or holding force of the band.
(6) "Brake - shoe type." A brake in which the holding effect is obtained by applying
the direct pressure of 2 or more segmental friction elements held to a stationary member
against a cylindrical wheel or drum affixed to the rotating member to be held.
(7) "Building face rollers." A specialized form of guide roller designed to contact a
portion of the outer face or wall structure of the building, and to assist in stabilizing the
operators' platform during vertical travel.
(8) "Continuous pressure." Operation by means of buttons or switches, any 1 of
which may be used to control the movement of the working platform or roof car, only as
long as the button or switch is manually maintained in the actuating position.
(9) "Control." A system governing starting, stopping, direction, acceleration, speed,
and retardation of moving members.
(10) "Controller." A device or group of devices, usually contained in a single
enclosure, that serves to control in some predetermined manner the apparatus to which it
(11) "Electrical ground." A conducting connection between an electrical circuit or
equipment and the earth, or some conducting body which serves in place of the earth.
(12) "Guide roller." A rotating, bearing-mounted, generally cylindrical member,
operating separately or as part of a guide shoe assembly, attached to the platform, and
providing rolling contact with building guideways, or other building contact members.
(13) "Guide shoe." An assembly of rollers, slide members, or the equivalent,
attached as a unit to the operators' platform, and designed to engage with the building
members provided for the vertical guidance of the operators' platform.
(14) "Interlock." A device actuated by the operation of some other device with
which it is directly associated, to govern succeeding operations of the same or allied
(15) "Operating device." A pushbutton, lever, or other manual device used to actuate
(16) "Powered platform." Equipment to provide access to the exterior of a building
for maintenance, consisting of a suspended power-operated working platform, a roof car,
or other suspension means, and the requisite operating and control devices.
(17) "Rated load." The combined weight of employees, tools, equipment, and other
material which the working platform is designed and installed to lift.
(18) "Relay, direction." An electrically energized contactor responsive to an
initiating control circuit, which in turn causes a moving member to travel in a particular
(19) "Relay, potential for vertical travel." An electrically energized contactor
responsive to initiating control circuit, which in turn controls the operation of a moving
member in both directions. This relay usually operates in conjunction with direction
relays, as covered under the definition, "relay, direction."