Gearboxes

Strip. The unit comes apart completely. Every gear, shaft, bearing and seal is removed, cleaned and laid out.

Inspect. Gears are checked for pitting, spalling, chipped teeth and wear on the tooth flank. Shafts are checked for straightness and for wear where bearings and seals ran. Bores are measured. The housing is checked for cracks and for bearing seats that have picked up damage.

Condition report. You get told what was found before anything is ordered or repaired. That report is what the decision is made on — whether to recondition, what to replace, and what it will cost.

Recondition. Bearings and seals are replaced as a matter of course. Worn shafts are built up and re-machined or made new. Damaged bearing seats are bored and bushed. Gears are replaced where the wear has gone past the working surface.

Reassemble and test. Backlash and end-float are set, the unit is run, and it is checked for temperature, noise and leaks before it goes back.

Noise that changes with load usually points at gear wear. Noise that changes with speed more often points at bearings.

Running hot can be a lubrication problem, a bearing starting to fail, or an overloaded unit.

Metal on the drain plug — fine grey paste is normal wear. Bright flakes are not, and mean something is coming apart.

Oil leaks are worth fixing early, and not only because of the mess. A gearbox that has been running low on oil has usually done damage that is more expensive than the seal.

A reconditioned gearbox is normally a fraction of the cost of a new unit, and available in a fraction of the time. Where a new unit is imported, the difference in lead time can be months.

There are cases where a recon does not make sense — a cracked housing, or a unit so far gone that nearly every component needs replacing. The condition report is what tells you which case you are in, and we would rather say so at that point than halfway through.

• The make, model and serial number if the plate is still readable
• What it is driving and roughly what it draws
• What it is doing that it should not be
• Whether the plant can run without it while it is out

Send it through and we will quote it.