Glossary T – Z

TORSION BALANCE —

1. a scale constructed with tensioned bands instead of knife edges or other bearings. Pivoting is achieved by the torsional twisting of the steel band, Fig. 69.
2. a sensitive balance using the torsion (twisting) of a fine filament for the resistant.*

TRANSPOSITION WEIGHING — the load is first weighed in one scale pan and then in the other pan. The true weight is then calculated as the square root of the product of the two weights obtained. TRUE WEIGHT = W1 x W2. Also called GAUSSIAN WEIGHING. 

TRIG LOOP — see TUMBLER. 

TRIP SCALE — a vibrating* counter scale (USA). 

TRUMPET END — an ancient Egyptian beam-end shaped like the bell of a trumpet, and using a cord pivot, Fig. 39 No.1 (Glossary K–P). The shape was revived during the Renaissance, but with a rudimentary knife edge and ring like a swan neck end.* Also called a LOTUS END. 

TRUTH — a scale is said to have truth when the beam at rest is horizontal, both when unladen and when equal masses are placed in the pans.

TUMBLER — a hinged catch used to immobilize or lock a scale beam, or a steelyard blade, when not in use, so preventing wear, Fig. 14 (Glossary C–D). Also called a TRIG LOOP (USA). See also LOCKING GEAR. 

TURN — a poise hinged at one end so that it can be turned to two weighing positions on the beam. It is typically used on folding gold balances,* Fig. 30 (Glossary E–J), and on some English bread scales. 

TURN-OVER STEELYARD — a steelyard having two (or more) suspension points and one load pivot, providing two ranges of capacity, one for light loads and one for heavier loads. The instrument is turned over to use the alternative suspension shackle* and to display the other graduations. Also called a REVERSIBLE STEELYARD.

TWO-KNIFE BALANCE — see SUBSTITUTION BALANCE.

ULTRA-MICRO BALANCE — see PRECISION BALANCE.

UNDER-AND-OVER SCALE — a trade scale with only a zero-line marked on the chart,* (USA). 

UNEQUAL-ARM BEAM — a scale beam in which the load pivot and weight pivot are located at different distances from the fulcrum to take advantage of the leverage so obtained. A common example is the steelyard.* 

UNSTABLE WEIGHBEAM — see ACCELERATING BEAM. 

VERIFICATION MARK — a mark or stamp used by inspectors of weights and measures to certify that scales or weights comply with regulations and are accurate. The stamp is punched or hammered into the metal surface. Also called an APPROVAL SEAL (USA). 

VIBRATING BEAM — a scale beam that rocks up and down before reaching equilibrium in a horizontal position. See also ACCELERATING BEAM. 

V-SPRING BALANCE — a balance that uses a spring in the form of a letter V, Fig. 73. The suspension loop and load hook are attached to the ends of the vee. Also called a SECTOR SPRING BALANCE. 

WATER WEIGHTS — see HYDROSTATICAL SCALES. WEIGHBEAM — see BEAM.

WEIGHBEAM — see BEAM.

WEIGHBRIDGE — a large type of platform scale* used to weigh road vehicles, railway trucks, barges, etc.

WEIGHING — the comparison of an unknown mass with a known mass. This is true, even for self-indicating scales, such as spring balances or pendulum balances, which are calibrated with reference to a known mass or masses. 

WEIGHMASTER'S BEAM — a steelyard, especially if used officially for verification of weights, (USA).

WEIGHT —

1. force arising from gravity when it acts upon the mass of a body.
2. a suitably shaped piece of material the mass of which conforms to a recognized system of units. In modern terminology, the term MASS is replacing WEIGHT. 

Many materials have been used to make weights, e.g., lead, stone, brass, bronze, copper, aluminum, iron and other metals, glass, earthenware, seeds, etc. There are many traditional forms of weight, which fall into three major categories: Geometric, Figurative, and Symbolic. Some of the more common ones are shown in Fig 74. See also:  POISE, COUNTERPOISE, CHAIN BALANCE, RIDER, PROPORTIONAL WEIGHT, WIRE WEIGHTS, WATER WEIGHTS, TARE POISE, CURRENT WEIGHT, FRACTION WEIGHTS, GROSS WEIGHT, NET WEIGHT.

 Key to Figure 74

Several of the above terms may apply to a single weight, e.g., No.36 is an oval bar weight. No.57 is round, tapered, knobbed, and flanged. The term 'tapered' is considered easier to use than the more correct 'inverted truncated cone'.

WEIGHT BOX — a receptacle for weights when they are not in use. See also WEIGHT RACK. 

WEIGHT LIFTING SCALES, WEIGHT COLLECTING BEAM — a scale with a beam which collects weights automatically as it tilts, until sufficient numbers have been collected to balance the load, Fig. 71. 

WEIGHT PAN, WEIGHT PLATE — the receptacle on which weights are placed for weighing, Fig. 58 (Glossary Q–S). Also called a WEIGHT PLATTER (USA). A pan is concave, and a plate is flat. See also GOODS PAN. 

WEIGHT PLATTER — see WEIGHT PLATE 

WEIGHT PROVER — an instrument that proves whether an object is the correct weight, or not. If the object is not the correct weight, the instrument has no means of determining the actual weight. An example is the common English sovereign rocker, Fig. 54 (Glossary Q–S). 

WEIGHT RACK — a rack or bar for storing weights* when they are not in use, Fig. 14 (Glossary C–D). The weights are usually slotted. See also WEIGHT BOX. 

WIRE WEIGHTS — weights made of wire and used for precision balances.* The weights are shaped to indicate the denomination, the number of sides being equal to the number of units, Fig. 74 No. 49. 

YARDAGE SCALE — see YARN BALANCE. 

YARN BALANCE — a scale used to determine the characteristics of yarns and cloths, usually by weighing a small sample. Various designs are used, but one type is shown in Fig. 70. Also called a YARDAGE SCALE or ROVING SCALE (USA). 

ZERO ADJUSTER — the means of adjusting a weighing device to an accurate zero reading when unloaded.

^† Revised from original.