Neither is turning freely in a twin screw drive configuration.
A tandem truck is a truck with two drive axles.
A dump truck with two drive axles.
Three - the two drive axles, and the steer axle.
The "tandem" part means it has two drive axles, although it is possible for a tandem truck to be a 6x2 vehicle, and have only one of those be a live axle.
The average tandem axle truck can carry about 12 cubic yards of soil. Generally, a tandem axle truck has three axles.
Measure from the point the trailer connects to the truck to the center of trailer axle ( if a tandem axle trailer measure to the center point between axles) multiply by 2 and this will have you close to turning radius.
A tandem dump truck is as normal as any other dump truck. Tandem simply indicates that it has two drive axles (as opposed to a single axle, which only has one). A tandem dump is typically allowed to gross at 54,000 lbs. From there, some dump trucks have additional axles (lift axles) which allow them to haul more weight. They're named in accordance with the number of axles behind the cab (i.e., not including the steer axle). So a tandem dump with a single lift axle would be referred to as a tri-axle, with two lift axles it would be referred to as a quad axle dump, with three lift axles it would be referred to as a quint axle dump.... at four lift axles, they're typically referred to as 'centipedes'.
You need to be more specific about the configuration. Is a single axle straight truck, a tandem axle straight truck, a tandem axle straight truck with additional lift axles, a tractor trailer...?
It could be either. Tandem simply means that the power unit has two drive axles which operate in tandem. It's common in both articulated and straight trucks.
A truck with three rear axles and one of the axles is a drop axle that is only used when carrying heavy loads.
Depends on what exactly it is.. twin steer, tandem axle truck with pusher axles, etc. For a tandem with two pusher axles, 18 - 21 tons, dependent on location, local laws, wheelbase, road type, etc.
They come in many sizes and configurations. They could be single axle trucks, tandem axle trucks, tandem axle truck with additional lift axles, tandem axle trucks with a twin steer setup (and these may also have additional lift axles, as well), and even tractor-trailers with mixer trailers. You'd have to be a little more specific as to which one you had in mind.