Vacuum Pump Edwards E2M28 A373-17-984 As-is, CLEARANCE!

The motor is totally enclosed and is cooled by the motor-cooling fan which directs air along the motor fins. The motors are fitted with a thermal overload device. When the motor is too hot, the thermal overload device switches off the pump. The thermal overload device has an automatic reset; when the motor cools down, the device resets and the motor will restart.
An oil pressure system lubricates the pump shaft bearing surfaces and rotor sealing faces. The pump has an oil distribution valve which prevents discharge of oil to the pump interior after the pump stops. The pumping chambers are air-tight, so this arrangement also prevents suckback unless the gas ballast valve is open.

You can inspect the level and condition of oil in the oil box reservoir through the oil sight-glass. An oil filler-plug is fitted to the top of the oil box. The pump has two oil drain-plugs to allow either gravity oil drain or pressure oil drain.