Abstract: A boat lifting crane includes an upper frame, which in turn has two upper beams, and at least two pairs of carriages. Each carriage of each pair is mounted so that it can move on a respective upper beam and can translate for a respective stroke portion. The boat lifting crane further includes at least one lifting belt, which is extended between two carriages of a same pair of carriages. At least part of the stroke portion of a carriage of a pair of carriages is superimposed on at least part of the stroke portion of a carriage of another pair of carriages.

Abstract: A method for steering a gantry crane having wheel assemblies includes the steps of: initiating movement of the gantry crane; and rotating the wheel assemblies wherein the front wheel assemblies rotate in a first rotational direction and the rear wheel assemblies rotate in a second rotational direction. The first rotational direction is opposite to the second rotational direction. First side wheel assemblies rotate at a first rotational speed and second side wheel assemblies rotate at a second rotational speed, such that the gantry crane moves from a linear path to an arcuate path with a turning radius decreasing to substantially zero for rotation about a central axis.

Abstract: A boat lifting crane includes an upper frame, which in turn has two upper beams, and at least two pairs of carriages. Each carriage of each pair is mounted so that it can move on a respective upper beam and can translate for a respective stroke portion. The boat lifting crane further includes at least one lifting belt, which is extended between two carriages of a same pair of carriages. At least part of the stroke portion of a carriage of a pair of carriages is superimposed on at least part of the stroke portion of a carriage of another pair of carriages.

Abstract: A method for steering the wheel assemblies of a gantry crane, including the steps of beginning the steering of at least one wheel assembly in the desired direction; and setting the angular position of a moveable pointer indicating a theoretical position of the wheel assembly which is consistent with said desired direction. The following steps are also included: setting an increment value of the moveable pointer in a direction consistent with respect to the steering movement of the wheel assembly; calculating the angular difference between the angular position of the moveable pointer and the current position of the wheel assembly; and—increasing the increment value of the moveable pointer if the difference shows a decrease, or decreasing the increment value of the moveable pointer if the difference shows an increase.

Abstract: A method for steering a gantry crane having wheel assemblies includes the steps of: initiating movement of the gantry crane; and rotating the wheel assemblies wherein the front wheel assemblies rotate in a first rotational direction and the rear wheel assemblies rotate in a second rotational direction. The first rotational direction is opposite to the second rotational direction. First side wheel assemblies rotate at a first rotational speed and second side wheel assemblies rotate at a second rotational speed, such that the gantry crane moves from a linear path to an arcuate path with a turning radius decreasing to substantially zero for rotation about a central axis.