Given that there is a wire(s) labeled ''Z'' I'm going to say that this is probably not a 3 phase motor. Normally you only find Z labeled wire in a single phase. BUT, I'm not 100% positive. The circuit that you drew, looks like a standard reversing circuit for a single phase. The only 3 phase wiring diagrams I can find, are all numbered or have terminals U, V, W, but no Z
Normally the data tag on the motor will state pretty clearly if it a 1 phase, or a 3 phase.