This article claims to have identified the six-spoked-wheel-like Indus script signs as sexpartite-disc based solar, fire and metallurgical symbols used in Indus civilization. It identifies the six-spoked-wheel shaped pure-copper artifacts found from 4000 BC Mehrgarh as funerary solar-wheel amulets, and links them to the solar iconography ( ) depicted above a deity’s head in Indus tablets. It further argues that the wheel-based signs , found on certain inscribed copper/bronze implements, and also in seal/tablets, were symbols for metallurgy and metal-smithy related crafts and/or commodities, inspired from the fire symbolism associated with Indus solar-disc symbol . Similar spoked-wheel-like solar symbols have been used in ancient Mesopotamia, and Europe. Most importantly, the Vedic texts of ancient India repeatedly use spoked-wheel based epithets for the sun-god and the fire-god, and evince important links between the gods of sun, fire, and metallurgy. This article further claims that in Indus seal/tablet inscriptions, which according to the author’s previous articles, semasiographically/logographically encoded rules and information related to taxation, trade/craft licensing, commodity control, and access control, the solar-sign metonymically signified some type of ruler or ruling body, endowed with the sun-god’s divine authority. This possible metonymic usage of the wheel-sign as Indus script’s ruler-symbol, inferred from the general observation that people of ancient civilizations often associated rulers with divinities (especially solar divinities), and used divine symbols (especially solar symbols) as royal symbols (e.g., ancient Egypt, and Maya civilization), get strongly corroborated from various numismatic and textual evidences of ancient historical and pre-historical India, where rulers have been repeatedly associated with sun-gods, and wheel-symbols have been used as royal symbols. For example, in ancient India’s punch-marked coins, solar symbols and six-armed-wheel symbols were often used as royal symbols, whereas several Indic words for kings/rulers (e.g., "cakravartīn", "cakrin") are etymologically connected to the wheel-word (“cakra”). The use of a solar symbol as a royal symbol across Indus settlements indicate the existence of a pervasive sun-cult in Indus civilization.