U - Dictionary of Quarrying Terms

UBR: abbr. uniform business rate.

Ultrasonic test: A test for comparing the strengths of concretes as described in British Standard 1881: Part203.

Unbound aggregate: Drystone which is not mixed with cement or bitumen.

Unconformity:A substantial break in the continuity of deposition, where one rock formation is overlain by another that is not the next in geological succession. The underlying older rocks may have a dip which is in marked contrast with the overlying younger rocks.

Underflow: That proportion of the feed which has passed through the apertures in a screen deck.

Undersize: Material in a product of a size smaller than the lower nominal size; may be expressed as a percentage of the product.

Uni-flow: In washers, the mineral being treated and the wash water flow in the same direction and, in screening, the direction of vibration of an inclined screen is such as to assist the passage of mineral along the screen.

Universal coupling: Couplings used on the ends of the propeller shaft of motor vehicles to allow for the movement of the rear axle relative to the gear box. It consists of a modern version of Hooke’s coupling in which two yokes set at 90° to each other are joined by a trunnion block.

Universal motor: A fractional-horsepower motor which can work on both direct current and single-phase alternating current.

Upthrow: The amount, measured vertically, of upward displacement of beds caused by a fault.