Can a longer coupling spacer be fitted without reviewing the rotating assembly?

The short answer

No. A longer spacer changes the rotating assembly’s mass distribution, bending behaviour and potentially its balancing requirements. Equal end connections do not establish equivalent operating behaviour. A wind-generator layout change that increases shaft separation requires assessment of the selected spacer-coupling configuration.

Separate interface fit from rotating behaviour

A spacer can bolt between the same hubs while introducing additional unsupported length and mass. Those changes affect bending stiffness and inertia distribution, even if transmitted torque remains unchanged. The coupling’s axial spacing can also affect how angular deflections accommodate parallel offset. A nominal torque rating therefore does not validate every spacer length that can be physically manufactured.

Read length-dependent restrictions

KTR’s ZRS instructions include critical bending-speed information that depends on DBSE, illustrating a length-sensitive rotating constraint. Its numerical curves apply to the specified product and cannot be transferred to another spacer. A longer component may also require its own balance boundary, handling support and guard envelope. A previously acceptable short assembly does not automatically prove those characteristics for an extended one.

Request the exact spacer configuration assessment

Ask the coupling supplier to identify spacer length, material/section, maximum operating speed, applicable bending assessment and balance requirements for the proposed arrangement. Have the drivetrain designer confirm the connected shaft and bearing conditions. MARSTON coupling dimensions and architecture remain unconfirmed. Do not extend a spacer with an improvised adapter or treat lower average wind power as a substitute for the speed check. The useful decision is whether the complete longer rotating connection is supported by its own manufacturer evidence. The longer spacer’s centre of mass and support conditions also belong in its handling instructions. Those practical details should remain separate from evidence that the spacer is dynamically suitable while rotating between the connected machines.