The earliest scales were small weighing instruments with wooden poles or metal poles with star points and tapers as the main body, and equipped with mounds (weights), mound ropes and weighing pans (or weighing hooks). According to the scope of use and the size of the scale, it is divided into three types: the scale, the pan scale and the hook scale. The steelyard is a first-arm lever, which is a simple weighing instrument that uses the principle of lever balance to weigh the weight. It is composed of a wooden scale beam with a scale star, a metal scale hammer, and a rope.

Jw-210 Square 5kg 304 Stainless Steel Kitchen Scale

Steelyards consist of levers of the first type, the weight of which is at the outer end of the fulcrum. When weighing, according to the weight of the object to be weighed, the mound and the mound rope are moved on the beam to maintain balance. According to the star point on the scale beam corresponding to the weight rope at the time of balance, the quality indication value of the object to be weighed can be read. The steelyard is simple in structure and manufacturing process, light and small, easy to carry and use, low in cost, but low in accuracy.

The steelyard is one of the oldest kinds of weighing instruments invented by human beings. Among the cultural relics unearthed before 700 BC from the tomb of Chu in the eastern suburbs of Changsha, Hunan, China, there are various refined weights, scale beams, weighing pans, silk threads tied to the weighing pans, and lifting ropes.

Among the cultural relics unearthed before 200 BC from Han tombs in China, there are steelyard mounds of various specifications. In 1984, in a single-kiln brick tomb of the Han Dynasty in Yaoshang Village, Changxing Town, Meixian County, Shaanxi Province, China, a complete wooden steelyard relic was found, which was made between the 1st century BC and the 1st century AD.