Which type of fit is characterized by a space always present between assembled parts?

The type of fit characterized by a space always present between assembled parts is a clearance fit. In this arrangement, the dimensions of the mating parts are such that there is intentional space or clearance. This clearance allows for free movement between the parts, facilitating easier assembly and disassembly, and reducing friction during operation. It's commonly used in applications where parts need to slide or rotate against each other without binding.

In contrast, interference fit involves parts that are so tightly fitted that they cannot be assembled without force, creating a tight connection. Transition fit is a combination of clearance and interference, which means there could be either a small amount of space or slight interference depending on the manufacturing tolerances. A press fit is also a type of interference fit, where one part is pressed into another, creating a strong bond.