Clearance


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clearance

1. 
a. the disposal of merchandise at reduced prices
b. (as modifier): a clearance sale
2. the act of clearing an area of land of its inhabitants by mass eviction
3. Dentistry the extraction of all of a person's teeth
4. a less common word for clearing

Clearance

 

the maximum profile of an object. As applied to transport vehicles and the moving parts of stationary machines, clearance is determined on the basis of their safe movement among other machines and structures. Outside the clearance, which permits the movement of machines in different directions, it is possible to erect structures and set up machines, lathes, and the safety zone for people. For example, the clearance of a moving train is the maximum profile in a plane perpendicular to the axis of the railway track beyond which no part of a locomotive or car should project when in working order. A railway clearance gauge is the maximum profile in a plane perpendicular to the axis of the railway track within which no parts of structures and equipment should extend. Meeting these clearances ensures the safe movement of trains in tunnels, on bridges, and under over-bridges. Underbridge clearance is the profile of the clear opening under a bridge between the bottom of its span structure and the estimated navigable level in height and between the supports of the span in width.

REFERENCES

Evgrafov, G. K., and N. N. Bogdanov. Proektirovanie mostov. Moscow, 1966.
Evgrafov, G. K., and N. N. Bogdanov. Zheleznye dorogi. Moscow, 1968.
Evgrafov, G. K., and N. N. Bogdanov. AvtomobiV. Ekspluatatsiia i remont. Entsiklopedicheskii slovar’-spravochnik. Moscow, 1968.

I. A. IVANOV


Clearance

 

the distance from ground level (plane of reference) to the lowest structural member of a motor vehicle, excluding the wheels; one of the parameters that determine the operational trafficability of motor vehicles.

The minimum permissible clearances established in the USSR are 200 mm, 240 mm, 260 mm, and 270 mm for fully loaded trucks with carrying capacities of 1.5 tons, 3 tons, 5 tons, and 8-12 tons, respectively, and 240-270 mm for buses, depending on their length and purpose.

clearance

[′klir·əns]
(engineering)
Unobstructed space required for occasional removal of parts of equipment.
(mechanical engineering)
In a piston-and-cylinder mechanism, the space at the end of the cylinder when the piston is at dead-center position toward the end of the cylinder.
The ratio of the volume of this space to the piston displacement during a stroke.
(mining engineering)
The space between the top or side of a car and the roof or wall.
(navigation)
The clear space between a vessel and an object such as a navigation light, hazard to navigation, or another vessel.
A specific message from air-traffic control to a pilot of an aircraft allowing him to proceed in accordance with the flight plan which the pilot had filed, or with some modification of the original plan.
In the instrument landing system, the difference in the depth of modulation which is required to produce a full-scale deflection of the course deviation indicator needle in any flight sector outside the on-course sectors.
(ordnance)
Elevation of a gun at such an angle that a projectile will not strike an obstacle between the muzzle and the target.
(petroleum engineering)
The annular space between down-hole drill-string equipment, such as bits, core barrels, and casing, and the walls of the borehole with the down-hole equipment centered in the hole.

clearance

1. Open space between two elements of a building to aid in proper placement, to compensate for minor inaccuracies in cutting, or to allow unobstructed movement between parts.
2. The space or distance allowed for anchorage or erection processes or to accommodate dimensional variations in the building structure.

air traffic control clearance

Authorization for an aircraft to proceed under conditions specified by an air traffic control unit (ICAO). This is to prevent collisions between known aircraft. The pilot-in-command of an aircraft must not deviate from the provisions of VFR (visual flight rules) or IFR (instrument flight rules) air traffic clearance except in an emergency or unless an amended clearance has been obtained. Additionally, the pilot may request a different clearance if he or she has information available that makes another course of action more practical or if aircraft equipment limitations or company procedures forbid compliance with the clearance issued. Pilots may also request clarification or amendment, as appropriate, any time a clearance is not fully understood or is considered unacceptable because of safety. Controllers should, in any such instance and to the extent of operational practicality and safety, honor the pilot's request. The pilot is responsible for requesting an amended clearance if ATC issues a clearance that would cause him or her to deviate from a rule or regulation, or, in the pilot's opinion, would place the aircraft in jeopardy. Normally, only the word clearance is used, and it may be prefixed by words such as start-up, taxi, takeoff, departure, approach, or landing to indicate the particular portion of flight to which the ATC clearance relates. Also called an air traffic clearance.
References in periodicals archive ?
I have rapists, pedophiles and people involved in child porn -- I have all these things at the interim clearance level and I'm pulling their clearances on a weekly basis," the senior Pentagon official added.
If you're good to go, then click "APPLY FOR CLEARANCE.
This expression multiplies the ratio of the viscosity in the channel and flight clearance times the ratio of the depth to the width of each.
Likewise, MED has adjusted its medical clearance criteria in response to advances in medicine.
The MOTs' assessments then are compiled and distributed through briefings or e-mail messages to all of the route clearance community.
Officials request that brush clearance for residences in more urban areas - the more brush and vegetation that surrounds a residence, the larger the defensible space should be - should allow a minimum of 30 feet between the structure and the edge of flammable or combustible growth.
3) Examples of the type of records that must be physically verified for a top secret clearance by an investigator include those associated with birth, education, residence, credit, employment, and military service.
The United Nations initiated a review of the International Standards for Humanitarian Mine Clearance Operations in October 1999 to form part of a wider international review and revision of mine action standards and guidelines.
Laboratory tests were conducted to determine how the sectional profile of a rotor (angle, tip width, tip clearance and number of wings) affects the mastication of rubber (Mooney reduction) and the mixing of a master carbon batch (micro dispersion) of carbon black and silica.
When DeVolpi showed the security reviewers his original, ten-year-old manuscript, bearing the official stamp clearing it for publication, they confiscated that document, seized his computer, and revoked his clearance.
Patrick Parkinson and Jeff Stehm-Staff, Board of Governors Adam Gilbert, Emily Gollob, Lauren Hargraves, Richard Mead, and Mary Ann Taylor-Staff, Federal Reserve Bank of New York Prepared as a staff study in fall 1991 Interest in clearance and settlement arrangements in securities markets by the Federal Reserve and other central banks reflects an increasing awareness that disturbances in settlement processes in those markets can adversely affect the stability of payment systems and the integrity of the financial system generally.
The clearance angle is also important, particularly in combination with low rake angles, because the workpiece springs back after separation from the chip.