Weight training equipment is varied and diverse in type and function. You can even use your own body weight for exercises like pushups and squats. As far as physical equipment goes, you can use free weights like dumbbells and barbells, or bands and tubes, and gym machines, frames and workstations based on levers and cables. Here are my top 10 gym machines and workstations for weight training.
The Lat Pulldown is a classic 'pull' exercise, usually with a cable machine in which you pull a weighted cable (or lever alternative) to face level. This movement works primarily the latissimus dorsi (lats), the large muscles below the shoulder blade on either side of the back.
Most gym goers know this one. You sit on a platform and grasp a handle that you pull toward you, maintaining good form with a straight back while squeezing the shoulder blades. Like the pulldown, weight can be adjusted with pins or other mechanisms, depending on the type of machine. This exercise targets the latissimus dorsi muscles of the back as well.
This rack with adjustable bar of (usually) 10 kilograms, is a versatile frame that allows you to do bench presses and squats within a frame that provides for you to lock the fixed bar in place on hooks on either side of the front uprights. Although the Smith Machine is useful for amateurs and beginners, using too much weight on the machine can be dangerous unless a 'spotter' is used -- especially in a bench press.
This is sometimes called a Hyperextension Bench. Either way, it allows you to hook your feet under a pad or pads, lower your torso across another pad, and lift again to return to the starting position. The forward movement flexes the back and the return extends the back. If you go past the natural line of the back on the return, this is called 'hyperextension.' This exercise works the abdominals and lower back. Taking support for the torso away creates a similar exercise called the glute-ham raise (gluteus-hamstring raise), which is a highly recommended exercise for the hamstring muscles.
Hack Squat Machine
Like the Smith machine, the Hack Squat machine takes away the instability of the free standing squat by providing a fixed path. This has benefits and disadvantages. Fixed path machines don't invoke extra muscles such as stabilizers and synergists. However, they do provide a little more control for beginners and people with certain incapacities -- as long as heavy weights are not attempted.
The Cable Station is a large frame with extensible cable handles with pulleys at each end. The position of the grips can be moved up or down to suit various exercises. You can even grasp one with each hand to do chest exercises. Some systems incorporate a pullup/chinup bar at the top. Many different upper and lower-body exercises can be performed with this station. It has many uses in rehabilitation exercise.
Unilateral Low Pull
This paddle-type machine has independent grips on either side and a chest pad for support allowing you to pull with either or both arms in a downward path similar to a swimming stroke. This station works triceps, shoulders and lats.
Overhead Press Workstation
The Overhead Press seated workstation is another piece of equipment that replaces dumbbells or barbells for standard overhead lifts like the military press or push press, except from a seated position.
Most gyms have a pullup/chinup bar either as a stand alone piece, or incorporated into another frame. Pullups are very good compound exercises for back and arms, especially when grip is varied from facing away to facing.
This workstation has a sliding knee pad plus grips at the dip position and also above at the pullup position. You can do "assisted" dips for triceps or pullups for arms and back. Not bad for beginners who are a little weak in the upper body.