A line which is perpendicular to the intersection of the after edge of the rudder-post with the designed load water-line. This is the case for both single- and twin-screw merchant ships. For some classes of warships, and for merchant ships having no rudder-post, the after perpendicular is taken as the centre-line of the rudder stock.
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RESTRICTOR
A device for producing a deliberate pressure drop or resistance in a line by reducing the cross-sectional flow area.
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GRID RHUMB LINE
A line making the same oblique angle with all grid meridians. Grid parallels and meridians may be considered special cases of the grid rhumb line.
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HAND LEAD
A light sounding lead (7 to 14 pounds), usually having a line of not more than 25 fathoms
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GROUND LOG
A device for determining the course and speed over the ground in shallow water consisting of a lead or weight attached to a line. The lead is thrown overboard and allowed to rest on the bottom. The course over ground is indicated by the direction the line tends and the speed by the amount of line paid out in a unit of time.
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False brinelling
False brinelling of needle roller bearings is actually a fretting corrosion of the surface since the rollers are the I.D. of the bearing. Although its appearance is similar to that of brinelling, false brinelling is characterized by attrition of the steel, and the load on the bearing is less than that required to produce the resulting impression. It is the result of a combination of mechanical and chemical action that is not completely understood, and occurs when a small relative motion or vibration is accompanied by some loading, in the presence of oxygen.
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AXIAL-LOAD BEARING
A bearing in which the load acts in the direction of the axis of rotation.
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CASE DRAIN FILTER
A filter located in a line conducting fluid from a pump or motor housing to reservoir.
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ELASTOHYDRODYNAMIC LUBRICATION
In rolling element bearings, the elastic deformation of the bearing (flattening) as it rolls, under load, in the bearing race. This momentary flattening improves the hydrodynamic lubrication properties by converting point or line contact to surface-to-surface contact.
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EP (EXTREME PRESSURE) LUBRICANTS
Lubricants that impart to rubbing surfaces the ability to carry appreciably greater loads than would be possible with ordinary lubricants without excessive wear or damage.
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BRINELLING
Permanent deformation of the bearing surfaces where the rollers (or balls) contact the races. Brinelling results from excessive load or impact on stationary bearings. It is a form of mechanical damage in which metal is displaced or upset without attrition.
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