You need a crane for general company needs or a specific project. That's great, but how do you pick the right system for your situation? It's important to understand the major features of cranes so you can assess the pros and cons of specific setups.
The ability to move is one of the most distinguishing features between systems. Some cranes have wheels that make them easy to move around sites with paved or concrete surfaces. However, you might need to move up to a tracked system to move the crane in and out of a location with rough terrain. If there's water nearby, you can even acquire a crane that floats.
Many cranes are not mobile. The main advantage of these systems is you can provide dramatically more support for non-mobile cranes. If you need to install extensive crane rigging to lift lengthy steel beams for a major construction project, this will likely be your solution. Mobile cranes are typically smaller and limited in their lifting capacities, although some of the larger tracked models may be up to the job.
Eventually, you're going to lift something with the crane. How each model of crane does the job differentiates it from others. At the high-capacity end, you'll find bridge models that straddle what they're lifting. These are often used for loading at industrial sites.
Tower cranes are the fixed models you often see used to build high-rises. These have arms that reach over the lifting and placement zones. Less bulky than other models, the tower crane doesn't hold up as well to massive lifting jobs. However, they can easily turn and work well on projects where loads are constantly going up. You can find telescoping hydraulic-powered models, too. These have arms to lift materials and are most appropriate for situations where mobility and flexibility are critical.
Hammerhead cranes try to strike a balance between the load capacity of bridge models and the flexibility of tower cranes. They aren't as tall as the tower models, but they do provide the turning capacity that's missing from a bridge system. A hammerhead uses a counterbalance to stabilize heavy loads. All that bulk also makes them less prone to damage in high winds when compared to tower models.
Stacker cranes represent a special use case. They use an elevator-like mechanism and are usually reserved for difficult work environments, especially sub-zero conditions where hydraulic components may fail. A carriage moves the materials up and down a fixed shaft, leaving them mostly for warehouse and long-term construction use.