Railwatching.com--Glossary of Railroads Terms -A

An improvement of the ABD Valve. Modifies the Emergency Portion and provides for accelerated buildup of brake cylinder pressure during quick service applications.

ABS - automatic block signal. This is a system for controlling trains. The track is divided into a series of blocks which are controlled by block signals activated by the presence of a train.

Absolute Block

A length of track in which no train or engine is permitted to enter while it is occupied by another train or engine.

Absolute Permissive Block (APB)

A designated section of track or tracks within which the movement of trains will be governed by block signals, whose indications supersede the superiority of trains. The block signals may be controlled manually or automatically.

Absolute Signal

A block or interlocking signal designated by an "A" market or the absence of a number plate.

A-end - the end of a railway car that does not have the brake handle. Opposite of B-end

Add, to

Couple car(s) to a train

Air Brake System

All of the devices and parts included in making an air brake for controlling the speed and stopping a locomotive or train. It is made up

of the operating devices, the pipes, fittings and foundation brake gear.

Alley

A clear track in a switching yard.

Angle Cock

An appliance used for the purpose of opening or closing brake pipe on ends of cars, rear ends of tenders, and front ends of switch engines so equipped. Provision is made for supporting hose at proper angle.

Anti-climber

A ridge on the front of a locomotive so that in case of a collision with another vehicle, it doesn't ride up into the locomotive cab

Application

Consists of all of the operations from the time the brake pipe reduction is started until the brake is released.

Approach Signal

A signal that governs the approach to another signal.

Automatic Block Signal System (ABS)

A series of consecutive blocks governed by block signals, cab signals or both, actuated by a train, engine or by certain conditions affecting the use of a block.

Automatic Cab Signal System (ACS)

A system which provides for the automatic operation of the cab signals and cab warning whistle.

Automatic Train Stop System (ATS)

A system actuated by wayside inductors, so arranged that its operation will automatically result in the application of the brakes until the train has been brought to a stop.

ARU

American Railway Union, Crushed during the Pullman strike in 1894

A-unit - a normal locomotive that has a control stand (different than a B-unit). Normally only used to differentiate a locomotive from a B-unit where they may share a similar body or engine. F7 locomotives were made in both A-unit and B-unit styles, for example.

Automatic Block Signal System (ABS)

A series of consecutive blocks governed by block signals, cab signals or both, actuated by a train, engine or by certain conditions affecting the use of a block.

Automatic Cab Signal System (ACS)

A system which provides for the automatic operation of the cab signals and cab warning whistle.

Automatic Train Stop System (ATS)

A system actuated by wayside inductors, so arranged that its operation will automatically result in the application of the brakes until the train has been brought to a stop.

Autorack - car carrier, usually multi-level, often enclosed,

Auxilliary - work train consisting of heavy crane, dining car, crew accommodation, equipment storage cars, cars of track panels etc that is deployed to clean up wrecks.