Detent

A detent is a device used to mechanically resist or arrest the rotation of a wheel, axle, or spindle. Such a device can be anything ranging from a simple metal pin to a machine. The term is also used for the method involved.

Detents are for example used to simply arrest rotation in one direction or to intentionally divide a rotation into discrete increments.

Mechanics

Arresting movement--the ratchet and pawl

To arrest movement, the method commonly employs a small gravity or spring-actuated lever paired with a notched wheel. The lever is mounted on a pivot point in proximity to the wheel.

The vertical angle of the sides of the notches that face the direction that rotation is desired is generally acute (45 degrees or less), so that as the wheel rotates in that direction, the end of the lever is easily lifted or pushed out and over the top of a notch. Following this, the lever drops into the next notch and the next et cetera as the wheel or shaft continues to spin.

The angle of the backside of the notch is severe (usually 90 degrees or greater to the end of the lever) so that the lever cannot be pushed up or out of the notch if wheel attempts to turn in the opposite direction. The lever is jammed between the back of the notch and its pivot point, stopping movement in that direction against any force that the materials used can withstand. The wheel has little resistance moving in the direction desired, other than that required to lift or push the lever over the next notch.

Détente

Détente (French pronunciation: ​[detɑ̃t], meaning "relaxation") is the easing of strained relations, especially in a political situation. Spanish uses the same word, detente, without the accent with the force of pronunciation in the second syllable (ten) to mean "stop."

The term is often used in reference to the general easing of the geo-political tensions between the Soviet Union and the United States which began in 1969, as a foreign policy of U.S. presidents Richard Nixon and Gerald Ford called détente; a "thawing out" or "un-freezing" at a period roughly in the middle of the Cold War. Détente was known in Russian as разрядка ("razryadka", loosely meaning "relaxation of tension").

The period was characterized by the signing of treaties such as SALT I and the Helsinki Accords. Another treaty, START II, was discussed but never ratified by the United States. There is still ongoing debate amongst historians as to how successful the détente period was in achieving peace.

After the Cuban Missile Crisis of 1962, the two superpowers agreed to install a direct hotline between Washington D.C. and Moscow (the so-called red telephone), enabling leaders of both countries to quickly interact with each other in a time of urgency, and reduce the chances that future crises could escalate into an all-out war. The U.S./U.S.S.R. détente was presented as an applied extension of that thinking. The SALT II pact of the late 1970s continued the work of the SALT I talks, ensuring further reduction in arms by the Soviets and by the US. The Helsinki Accords, in which the Soviets promised to grant free elections in Europe, has been called a major concession to ensure peace by the Soviets.