An overhead crane VFD quotation should identify each motion separately: hoisting, trolley travel and bridge travel. The loads and duty can differ even when two motors have the same rated power. Make one line in the RFQ for each motion and show how many motors it drives.
What to record for each motion
| Motion | Data to include |
|---|---|
| Hoist | Rated load and lifting speed, motor plate, required low-speed operation, lowering frequency, holding brake and encoder details. |
| Trolley travel | Trolley and load mass, target speed, acceleration and deceleration, motor plate, end limits and brake arrangement. |
| Bridge travel | Bridge and load mass, number of driven wheels and motors, motor plates, whether both sides share a drive, travel limits and any skew control. |
Where do braking and feedback affect the quote?
For the hoist, document the lowering cycle and the existing electrical braking hardware so the supplier can review how the energy will be handled. List the mechanical brake, its supply and its feedback contacts separately. If a motion uses two motors on one drive, send both nameplates and ask the supplier to verify current, overload and motor protection for that topology. Include encoder type and supply wherever feedback is required.
What should be on the returned quotation?
Ask for the exact drive and option codes per motion, and identify which braking, feedback and communication components are included. Have the crane engineer approve the control scheme and protective functions before commissioning. The hoisting-duty selection guide covers vertical lifting duty, and the crane braking options guide compares two ways to handle generated energy. For the drive family, see S700 crane VFD.