Switch
Mark Mandell and others,
The switch that you need if you run the pump on 240 VAC is a DPST (not DPDT, although you could use a DPDT switch). Someone asked what DPDT means -- it is Double-Pole Double-Throw. DPST is Double-Pole Single-Throw.
I have been using a 1/4 HP GAST dry rotary vane vacuum pump and the model that I have is slightly different -- it can be wired for either 120 or 240 VAC by just changing jumpers inside the terminal plate. I don't understand the need to get one that runs on 240 VAC, after all, it is just a 1/4 HP motor. Concerning using a transformer: as an electrical engineer, I will second what the other EE said. Unless you get a transformer specifically for an inductive load, it will not work well. The typical isolation / step-down transformer is intended for resistive loads (lighting) and not highly reactive loads. And, the one that the Surplus Center has is inadequate anyway. If you total up the cost of pump plus transformer, that is too much money. Here is a helpful hint: Go to eBay and pay much less for something that better suits your needs. I bought one that is essentially identical to the one that Craft Supply sells for $360 and it cost me $25 plus about another $25 for shipping.
Bill