ANSI: The American National Standards Institute, from whose criteria the OSHA standards for safe operation of cranes and derricks and other systems using wire rope isntallations are derived.

birdcaging: An expansion of the strands laid into a rope; usually caused by twisting against the lay (q.v.).

block: A system of sheaves (q.v.) sharing a common frame, and (usually) a common axle.

compounding: A system of sheaves and weight lines designed to provide a shorter weight drop for (or a mechanical advantage in lifting or supporting) a weight. The decrease in weight fall is found by multiplying the total weight fall necessary by the inverse (1/number of falls) of the number of falls (q.v.). The mechanical advantage is computed by counting the number of falls going to and from the moveable sheave(s) attached to the weight.

core: The core material, either metallic or non-metallic, around which the strands of the rope are helically laid. Cores are made of fiber (FC), a wire strand (WSC), or an independent wire rope (IWRC).

Crosby clip: A fastening device, also known as a U-clamp. A bolt in the shape of a U, used with a forged saddle to terminate a wire rope, usually in a loop. Strength of a clamped loop is 80% of wire rope rating.

fall: Any weight line which directly supports the driving weight. For a single fall, the weight line is attached to the winding barrel at one end and the weight at the other, without any compounding pulleys. Compounding requires at least one pulley, and results in multiple falls at the weight. Two lines at the weight is two-fall compounding, three lines is three-fall compounding, etc. Increasing the number of falls increases the compounding advantage, but also increases losses due to pulley bearing friction.

fiddle block: A block consisting of two pulleys in the same vertical plane held in place by their common cheek pieces.

fleet angle: The angle between the sheave/barrel centerline and the rope at its extreme deflection. The fleet angle should not be less than 1/2°, and should not exceed 2°.

fleeting pulley: A pivoted guide pulley whose pivot should be aligned with the centerline of the barrel and placed at a distance from the barrel determined by this formula: Dw x .5 / .035, where Dw is the depth (or width) of the barrel; multiplying by .5 takes half of the depth; .35 is a constant derived by trigonometrically solving for the adjacent by dividing the opposite by the tangent (.03492) of 2°. The rule of thumb is 1 .25 feet of separation between the barrel and the first, or main, pulley for each inch of barrel depth or width. The fleeting pulley must not be used as the lead sheave (q.v.)

fleeting sheave: A self-aligning sheave (grooved wheel or pulley) mounted on a horizontal shaft, which will allow the sheave to move from side to side as the rope winds on or off the barrel. See fleeting pulley for location and alignment data.

guard pin: A pin or bolt through the cheek-pieces of a pulley, so placed as to prevent the wire rope from leaving the groove in the sheave (q.v.).

lay: (or laid) The lay is the direction of the helical path in which the strands making up the rope are laid. If the strands form a helix similar to the threads of a right-hand screw, the lay is called right, or right-hand; if the strands wind around to the left the lay is called left, or left-hand. In Lang lay rope the wires in the strands and the strands spiral in the same direction.

lead sheave: The first, or main sheave, or pulley for the rope as it comes off the winding barrel. See fleeting pulley for location and alignment data.

OSHA: Office of Safety and Health Administration. For information on safety requirements applicable to tower clocks, contact the local or regional Office.

overwound barrel: A winding barrel system in which the cable passes over the barrel as it is wound on. A right lay rope on an overwound barrel should start from the right hand flange, and a left lay rope from the left flange. See underwound barrel:

plow steel: Plow steels, made in grades ranging through plow, mild plow, improved plow to extra improved plow, are high-carbon (.45 to .80%) steels, used primarily in the manufacture of wire ropes.

pulley: The common, or laymanıs term for a grooved wheel. See Sheave.

reeving: A term used to describe the path of the wire rope through a system of blocks. A reeving diagram is a pictorial rendering of the desired path for the wire rope.

rock weights: Typical weights per cubic foot for various materials commonly used in tower clock weight systems: bricks; 125; cement, 137; granite, 168; gravel, 109; limestone, 162; marble, 168; sandstone, 143; slate, 175; soapstone, 168; sand (dry), 100.

sheave: A wheel with a grooved rim, mounted in a frame; a pulley wheel or any similarly grooved wheel, used to guide or change the direction of the rope or cable.

snag: A broken wire protruding from the body of the rope, indicating that the rope is probably stressed, either by excessive weight, or, more commonly, by bending around a sheave whose diameter is too small.

snatchblock: A block or pulley with one removable or pivoting cheekpiece, whereby the pulley can be located in the middle of a cable already solidly fastened at both ends.

soldering: Attaching a terminal to a wire rope with pure molten zinc. Strength rating is 100% of wire rope rating.

stop cable: A safety device attached to a weight to prevent its falling beyond the limits imposed by the length (and strength) of the stop cable.

strand: A wire rope strand is made up of wires; the strands are then laid (q.v.) into a wire rope.

swage: To fasten a termination to a wire rope by physically deforming the termination around the rope; as by hammering, or by hydraulic press. Strength is 100% of wire rope rating.

termination: Any of a number of devices and methods used to place a working terminal on a wire rope. Swaging (q.v.), soldering (q.v.), and U-clamps (q.v.) are common fastening methods.

thimble: A grooved metal reinforcement (in a teardrop shape) placed in a wire rope loop to prevent chafing and cutting.

U-clamp: A fastening device, also known as a Crosby clip. A bolt in the shape of a U, used with a forged saddle to terminate a wire rope, usually in a loop. Strength of a clamped loop is 80% of wire rope rating.

underwound barrel: A winding barrel system in which the cable passes underneath the barrel as it is wound on. Start a right lay rope from the left flange, and a left lay rope from the right flange. See overwound barrel:

Publications:

The catalog of ANSI standards may be ordered from:

The American National Standards Institute
11 West 42nd Street,
New York, New York 10036
Tel: (212) 642-4900

Copies of each of the standards have to be ordered from the catalog, unless your local library happens to have copies.