Guide
Industrial gearbox repair: what drives cost and lead time
Updated
On an industrial unit the repair price is rarely the number that matters. Lead time is, because the line is stopped while you wait.
What a specialist is actually pricing
- Strip, clean and inspect. Dismantle to component level, clean, measure and report. Chargeable, and normally credited against the rebuild if you proceed.
- Wear parts. Bearings, seals, gaskets, circlips and shims. On a current-production unit these are stock items; on an obsolete one they may not be.
- Gears. Inspection for pitting, spalling and tooth damage. Replacement gears may be available, may be pattern, or may have to be cut to order from the old ones.
- Machining. Line boring or sleeving worn bearing housings, building up and regrinding shafts, skimming mating faces, crack repair or welding a damaged case.
- Rebuild, set-up and test. Backlash, preload and end float set to spec, then a run test with noise and temperature checked under load.
- Paint, protect and paperwork. Finish, preservation for storage, and the report and warranty documentation you keep on file.
Where lead time comes from
| Item | Effect on lead time |
|---|---|
| Stock bearings and seals | Little or none; usually next day |
| Standard replacement gears from the maker | Days to weeks, depending on the maker and the ratio |
| Gears cut to order | Weeks, and the single biggest driver on obsolete units |
| Housing line boring or sleeving | Adds machine shop time, and competes for the same machines as other jobs |
| Shaft building up and regrinding | Similar; specialist process, often subcontracted |
| Casing crack repair | Variable, and sometimes the point at which a replacement case is the better answer |
| Exchange unit off the shelf | Shortest by a distance, where one exists for your drive |
Get the nameplate before you ring anybody
Maker, type, ratio, serial number and, if it is there, the mounting arrangement and input power. Photograph the plate and photograph the unit in situ, including the couplings and how it is mounted. A specialist can check parts availability from a plate in minutes, and that check is the difference between a useful price and a shrug. If the plate is gone, good photographs of the casing, the shaft ends and the mounting feet will often let an experienced firm identify it anyway.
Downtime is the real number
Work out what an hour of that line being down costs, then price the options against it. A more expensive exchange unit that gets you running on Thursday can be dramatically cheaper than a rebuild that gets you running the following month. The other side of the same coin is planning: a spare unit on the shelf, or a rebuilt swap-out held for a critical drive, converts a crisis into a scheduled job. That is also the cheapest way to comply with the maintenance duty, since HSE guidance on PUWER requires work equipment to be maintained in an efficient state, in efficient order and in good repair (HSE).
If the drive is part of lifting equipment, a crane, hoist or winch, it also falls under LOLER as well as PUWER, and thorough examination requirements apply (HSE). Tell the specialist up front, because the paperwork on the way out is different.