A shaft coupling device to couple first (10) and second (12) shafts, said device comprising a fluid coupling (14) having a first portion (14a) attached to the first shaft (10) and a second portion (14b) attached to the second shaft (12) wherein the device further comprises engagement means (44) operable to switch the device between an engaged position and a disengaged position, the engaged position having each of the first and second shafts (10, 12) engaged with its respective portion (14a, 14b) of the fluid coupling and the disengaged position having at least one of the first and second shafts (10, 12) disengaged from its respective portion (14a, 14b) of the fluid coupling.