Heavy duty industrial gears sets including spur, helical and bevel designs require extreme pressure lubricant, to provide protection against shock loads. Further it should provide protection against wear and reduce sludge formation.
If a gearbox is known to be sludge-free the normal top-up procedure can be followed, in which the new oil is mixed with the original oil. Use oil of the same grade in the gear box to maintain the lubricant at filler plug level. Check the lubricant level at each lubrication job, and if required top up by adding frequent small quantities, rather than occasional large charges.
Inspect the system regularly at an interval of every 250 hours of operation, for an initial period of three months and thereafter the frequency may be extended gradually, to normal manufacturers’ recommended periods, as long as conditions are satisfactory.
As a general principle, oil that has been in use for some time should be renewed completely. Drain and refill the housings as per manufacturers’ recommended periods, or twice yearly whichever is earlier.