Correct option is D
To determine the maximum diameter of a workpiece that can be turned on a lathe, you need to consider the centre height and the gap bed depth.
Centre height = 320 mm
This means the maximum radius of the workpiece that can be accommodated is 320 mm, translating to a maximum diameter of 640 mm under normal conditions.
Gap bed = 150 mm
The gap bed allows for larger workpieces to be turned by removing a section of the lathe bed. When the gap bed is utilized, the maximum diameter of the workpiece increases by twice the gap bed depth (since the gap allows for additional clearance on both sides of the workpiece).
Thus, the additional diameter allowed by the gap bed is 150 mm × 2 = 300 mm.
Therefore, total maximum diameter = 640 mm + 300 mm = 940 mm.
