US Patent 7162900 Tubular lock and master key

A master key includes a key base having a key handle, a fixing seat and a sleeve, all of which are connected to each other integrally. The fixing seat has a plurality of angularly spaced apart spring holes having respective key springs. A key tube includes a large cross-section tube section inserted into the sleeve, and a small cross-section tube section fixed to the fixing seat. The large tube section includes a plurality of angularly spaced apart long and short grooves. The long grooves are aligned with the respective spring holes to receive slide pieces, and the short grooves have respective shoulder faces. A tubular lock to be used with the master key is also disclosed.