Pitting on gears; how to prevent this costly lubrication problem?
Pitting, pit formation, or pit corrosion on gears is a form of wear. It can be recognized by dark spots or shallow pits on the tooth flanks. These irregularities cause friction, resulting in significant heat generation. Without preventive measures, this leads to major problems, as in severe cases a gear can seize due to broken teeth. The consequence is damage to expensive transmissions and halted production processes, meaning loss of time and money. Proper lubrication helps prevent pitting.
Oil that underperforms under high pressures
Where gears mesh, high pressure occurs on the tooth flanks. A thin oil film over the tooth flanks ensures that metal parts do not rub directly against each other, while also dissipating heat. If that oil film is missing, metal presses on metal, causing locally extreme heat. The metal corrodes or even becomes liquid. This creates pits that keep growing. This is the result of using oil that underperforms under high pressures. This problem can be solved.
American research has shown that 60% of all damage to gear transmissions is caused by pitting or pit formation!
The case of Liebherr and Spierings cranes
A crane rental company in central Netherlands called on our help to solve a problem. We were faced with pitting issues in gearboxes of mobile cranes. The mobile telescopic cranes from Liebherr and mobile tower cranes from Spierings use final drive shafts from the manufacturer Kessler & Co. Regular oil from a well-known brand was used for lubrication. The results were downright disappointing. Due to pit formation, gears and oil often had to be replaced, causing cranes to be out of service. This was disastrous for a company that generates all its income from crane rentals.
Our specialists offered to solve the problem
Previous tests with other oil brands did not solve the pitting problem. Our specialists offered to tackle the issue. The worst-case gearbox was drained and flushed, and the gear with pitting was turned over. The gearbox was then refilled with Duolec® LE 1605 oil from the American producer LE (Lubrication Engineers). We know this oil performs well under extremely high pressures, such as those between the gears in this gearbox.
High-quality gearbox oil enriched with Duolec®
Test results: No more pitting
After an extended trial run, the gearbox was drained again. No new pits could be found on the gears. Laboratory oil analyses showed that the LE oil remained intact, contained no metal particles, and therefore did not need to be replaced. This resulted in significant time and cost savings for the customer.