General data: Universal heavy-duty gearboxes. Housing: High-quality grey cast iron, all sides machined and with mounting holes on 4 sides. Gearing: 13 ratios from 5 to 83 : 1; worm shaft hardened and ground. Worm gear made from special centrifugally cast bronze. Efficiency factor: The efficiency factors stated in the selection tables are guideline values for properly run-in and lubricated gearboxes at operating temperature with nominal load and driving worm shaft. Proper running in is a crucial factor influencing the lifetime of the gearbox. The starting efficiency factor is, as the operating efficiency factor, depending on the lead angle. Self-locking: Self-locking only occurs in worm gear units, when the unit cannot be driven from the output side. Worms with 4 and 6 threads sometimes permit transmission ratios for gearing up (i = 5 : 1 to 13.3 : 1). If a gearbox must be implicitly self-locking, or must implicitly not be self-locking, we urge you to contact us. Only the ratios 39:1 product No. 42101314 and 72:1 product No. 42101313 are generally self-locking and optimized for manual operation. Bearing system: All gearbox shafts with generously dimensioned roller bearings. Lubrication: The gearboxes are lubricated for life using synthetic oil. Under normal operating conditions, no maintenance is required. The housing should be checked for leakages at an interval of approx. 2 years. Ventilation: The sealing plug has to be exchanged with the separately packed venting filter.