multishaft

Multishaft refers to a mechanical power-transmission arrangement in which two or more shafts are used within a single drive train, either sharing a common prime mover or distributing power to multiple outputs. In a multishaft system, shafts may be concentric or side-by-side and are connected by gear stages, clutches, or couplings. The arrangement can be two-shaft, three-shaft, or higher, and may involve direct drive between shafts or intermediate gearboxes.

Common configurations include: a single input shaft driving multiple outputs through separate gear trains; multiple inputs feeding a common output; and cascaded shafts where speed-torque is modified across successive stages. The choice depends on speed ranges, torque requirements, and redundancy considerations. Multishaft arrangements are widely used in gas turbine and aero-engine design (high- and low-pressure shafts), marine propulsion, heavy industrial gearboxes, and wind or hydroelectric power systems with multi-drive units.

Advantages include better speed matching across varied loads, the ability to drive different machinery from a shared source, and potential redundancy. Disadvantages are increased mechanical complexity, alignment and vibration issues, more elaborate lubrication and cooling needs, and higher maintenance costs.

Design considerations cover torsional stiffness, balancing of rotating masses, accurate alignment of shafts and gear meshes, lubrication regimes, and control of clutch or brake engagement in systems with multiple inputs or outputs. Safety and reliability are crucial, given the potential for load-sharing imbalances and shaft losses.