BLUEMOMENT

... made heavy contact with Brodick Pier because the engine was slow to provide astern propulsion due to the engine becoming ‘locked’ at top dead centre, and the engineers controlling the engine could not rectify the matter quickly enough to prevent the collision.

... If the HP piston stalled at the full extent of its travel, either at the cover end or crank end, it was referred to as a dead centre event, which was rare. The crew did not routinely practice the procedure for resolving the situation as it was difficult to replicate since the engine would, in normal operation, pull on the LP piston, assisting the engine away from being locked dead centre. An HP piston dead centre event prevented steam from flowing through the engine. To overcome this, the engine was designed to enable impulse steam to be admitted directly into the MP or LP cylinders to start the engine rotating in the desired direction, or to reverse direction with steam applied.