7. When does a geared motor need an oil expansion tank?

Whether the use of an oil expansion tank is necessary for geared motors depends on the installation position and the operating conditions. This is often necessary, among other things, for spur gears, bevel gears, planetary gears or slip-on gears of the M2 (top shaft) + M4 (bottom shaft) design. For example, at higher loads / speeds / gear ratios, the gear oil could foam and escape from the vent screw. To prevent this, an oil expansion tank is used. An oil expansion tank is generally not necessary for worm geared motors.