Abstract: A railway car brake mechanism is comprised of a hand wheel on a shaft and a housing with a rotatable gear wheel and square chain winding disposed within. A ratchet wheel rotatable with the hand wheel shaft and a freely rotatable pinion which engages the gear wheel is also provided. The rotatable pinion has a flange with a disengageable driving connection with the gear wheel and a disengageable connection between flange and ratchet wheel. The main gear wheel and chain winding drum comprise a main gear wheel assembly. The assembly is attached by a chain end link through an interconnection of the main gear wheel and outwardly extending section of the chain winding drum. To prevent kinking or slippage of the chain, a spiral groove is formed in the square chain drum. The groove enables the chain to be wound within the drum with alternate links seated on a concave surface and intermediate links, which rest on the outer surface of the drum, to be at right angles to the aforementioned alternate links.