Oil Mist Lubrication-Wet Sump: Similar to Oil Mist Lubrication – Dry Sump, except that a pool of oil is developed in the bearing chamber. This oil pool will continue to supply oil to the bearing in the event that the oil mist is interrupted and is fed from a source outside the bearing housing such as a constant level oiler.

Open Bearing: A ball bearing that does not have a shield, seal or guard on either of the two sides of the bearing casing.

Open Externally Ventilated Machine: A machine which is ventilated with external air by means of a separate motor-driven blower mounted on machine enclosure.

Open (Protected) Motor: A motor having ventilating openings which permit passage of external cooling air over and around the windings. The term 'open machine', when applied to large apparatus without qualification, designates a machine having no restriction to ventilation other than that necessitated by mechanical construction.

Open Pipe-Ventilated Machine: An open machine except that openings for admission of ventilating air are so arranged that inlet ducts or pipes can be connected to them. Air may be circulated by means integral with machine or by means external to and not a part of the machine. In the latter case, this machine is sometimes known as a separately- or force-ventilated machine.

Open-Loop : A system in which there is no feedback. Motor motion is expected to faithfully follow the input command. Stepping motor systems are an example of open-loop control.

Operating Frequency: Operating frequency is the speed (revolutions per minute) times the resolution (lines per turn) divided by 60. Operating frequency = (RPM x Resolutuion)/60.

Outgassing: Evaporation of oil, dirt, or any other substance from a surface after it is placed in a low pressure or vacuum environment.

Overload Capacity: The ability of a drive to withstand currents above its continuous rating. It is defined by NEMA as 150% of the rated full-load current for "standard industrial DC motors" for one minute.


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