MODULAR TOP DRIVE

A modular top drive for construction of a wellbore includes a rail for connection to at least one of: a floor and a derrick of a drilling rig; and a motor unit. The motor unit includes: a first body; a drive motor having a stator connected to the first body; a trolley connecting the first body to the rail; and a first latch for selectively connecting either a drilling unit or a casing unit to the motor unit. The top drive further includes a bracket for holding any one of the drilling, casing, and cementing units and movable relative to the rail between a standby position and a connection position. The unit held by the bracket is aligned with the motor unit in the connection position and clear of the motor unit in the standby position. /4k 2 3 /3b if Id 5f 5h 12 I h lc 1 I 3f