When looking for a press brake, or brake press, you need to know what type of press you are looking for. Press brakes come in all sizes and with many different options. You can buy a brake press that is hydraulic, mechanical, air clutch, air trip, and of course CNC or computer numerical controled.

You need to first know your Capacity, which is rated by tonnage. Then you need to know the legnth and distance between housings. The distance between housings is usually smaller than the capacity of the machine. If you are looking to bend 10' and need to go past the gap, you will need a 12' brake.

As for the clutch, Hydraulic clutch is the safest, and most expensive. They are generally slower and have more of a precise bend.

Air clutch machine work in the same way except they use air to activeat the clutch. The difference is that you have to complete the rotation once activated. This makes it more dangerous, but faster.

Air Trip, is a cheaper, sometimes aftermarket clutch system that can be added to a standard mechanical brake press.

Mechanical is the most dangerous of them all, you lose alot of control. The clutch has to make a full rotation, and can't be stopped at any time during the process.

CNC press brakes are the latest in manufacturing. They can have mutiple axis Backgauges, and you can program them to do different bends. This is the most expensive and the best for production.

That should give you a basic rundown on how to purchase a press brake.