Abrasive wheel. A grinding tool consisting of bonded abrasive grains. This includes diamond and reinforced wheels.

Blind hole. A hole drilled in an object, such as an abrasive wheel, that does not go all the way through.

Blotter. A compressible disc or washer, usually of blotting paper, plastic, cardboard, or gasket material, that is used between the wheel and the flanges to evenly distribute flange pressure on the wheel.

Cone and plug wheels (Types 16, 17, 18, 18R, and 19). Abrasive wheels manufactured with blind hole threaded bushings. They may be used on all surfaces except the flat mounting surface (D). Specific characteristics of the different cone and plug wheels are:

(a) Type 16 cones have a curved side with a nose radius;

(b) Type 17 cones have straight sides with or without a nose radius;

(c) Type 18 and 18R plug wheels are cylindrical in shape with either a square or curved grinding end;

(d) Type 19 cone wheels are a combination of cone and plug shapes.

Cutting-off wheels. Abrasive wheels used to cut material such as masonry, pipe, etc.

Designated person. A person selected or assigned by the employer or the employer's representative as competent to perform specific duties.

Discharge opening. An opening in a mower housing for discharging grass.

Flanges. Collars, discs, or plates between or against which wheels are mounted. There are four types of flanges:

(a) Adaptor;

(b) Sleeve;

(c) Straight relieved;

(d) Straight unrelieved.

Grass catcher. Parts or a combination of parts to collect grass clippings or debris.

Guard (abrasive wheels). An enclosure designed to restrain the pieces of an abrasive wheel and furnish protection to the operator if the wheel is broken during operation.

Guard. A part or assembly to prevent accidental contact with hazardous machine parts or to protect persons from other hazards created by the machinery.

Inorganic bonded wheel. Abrasive wheels that are bonded by means of inorganic material such as clay, glass, porcelain, sodium silicate, magnesium oxychloride, or metal.

Jack. A portable hand- or power-operated mechanism for lifting, lowering, or moving horizontally a load by applying a pushing force.

Modified Types 6 and 11 wheels (terrazzo). Similar to Type 6 "straight cup" wheels and Type 11 "flaring cup" wheels except for the bottom of the cup. The bottom of the cup is flat in Type 6 and 11 wheels. The modified wheels have bottoms that are sloped downwards towards the mounting hole. These modified wheels need to be mounted using a special tapered flange furnished by the tool manufacturer. These wheels are used in the terrazzo trade.

Mounted wheels. Bonded abrasive wheels of various shapes, usually two inches diameter or smaller, that are secured to plain or threaded steel mandrels.

Normal service (jacks). Raising or lowering axial loads that are eighty-five percent or less of the rated load under controlled conditions.

Organic bonded wheels. Abrasive wheels that are bonded by means of organic material such as resin, rubber, shellac, or other similar bonding agent.

Rated load. The maximum load that the jack is designed to lift or support.

Reinforced wheels. Organic bonded abrasive wheels which have webbing, fabric or filament to provide resistance to complete breaking of the wheel should it become cracked or damaged.

Terrazzo. A material of stone chips, such as marble, set in mortar and polished.

Threaded hole wheels. Abrasive wheels that have one central threaded bushing, securely anchored in place. They are mounted by being screwed onto a threaded machine spindle so that the wheel back seats firmly against an unrelieved flat back flange.

Tuck pointing wheels. Tuck pointing abrasive wheels are Type 1 reinforced, organic bonded wheels and have diameter, thickness and hole size dimensions. They are used to remove cement, mortar, or other nonmetallic jointing material.

Type 1 wheel. An abrasive wheel shaped like a disc with a mounting hole in the middle. Sometimes called a "straight wheel." It has diameter (D), thickness (T), and hole size (H) dimensions. Grinding is normally done on the periphery (outside curve) of the wheel (T dimension). Can be used for grinding, cutting-off, and tuck pointing.

Type 2 wheel. An abrasive wheel shaped like an open-ended, hollow cylinder. Sometimes called a cylinder wheel. It has diameter (measured from the outer wall of the cylinder), wheel thickness (height of the cylinder), and rim thickness (thickness of the cylinder wall). Grinding is done on the end of the cylinder (rim thickness dimension).

Type 6 wheel. An abrasive wheel shaped like a straight-sided cup or bowl with a mounting hole in the bottom of the cup. Sometimes called a "cup wheel." It has diameter (D), thickness (T), hole size (H), rim thickness (W), and back thickness (E) dimensions. Grinding is normally done on the cup rim (W dimension).

Type 11 wheel. An abrasive wheel shaped like a cup or bowl with a mounting hole in the bottom of the cup. The sides of the cup are not straight-sided but are angled outward. Sometimes called a "flaring cup wheel" since the sides are "flared" out. It has double diameter dimensions (top D and bottom J). It also has thickness (T), hole size (H), rim thickness (W), and back thickness (E) dimensions. Grinding is normally done on the cup rim (W dimension).

Type 16, 17, 18, 18R, and 19 wheels. See cone and plug wheels.

Type 27 wheel. An abrasive wheel similar to a Type 1 wheel, but the center of the wheel around the mounting hole is pushed back (depressed). Sometimes called a "depressed center" wheel. It has diameter (D), thickness (U) and hole size (H) dimensions. The depressed center allows grinding on the flat surface of the wheel without interference from the flange or mounting hardware.

Type 27A cutting-off wheel. Similar to a Type 27 wheel. Specifically designed for use on cutting-off machines.

Type 28 wheel. An abrasive wheel similar to a Type 27 wheel, but the face of the wheel is angled upward and away from the mounting hole. The face of a Type 27 wheel is flat and perpendicular to the mounting hole. A Type 28 wheel is also called a "depressed center" wheel. It has diameter (D), thickness (U), and hole size (H) dimensions. The depressed center allows grinding without interference from the mounting. A Type 28 wheel has a saucer-shaped grinding rim and is designed for corner grinding and side grinding.

Type 29 wheel. An abrasive wheel that has reversed, saucer-shaped grinding rims (similar to a partially opened umbrella).