devices which are able to inject (mix) concentrated fertilizers and chemicals with flowing water in an irrigation system. There are two types of injectors: venturi, (vacuum type) and hydraulic type (water drives a piston pump).

The water supply to the boiler was provided by two live steam injectors, or one live steam and one exhaust injector on larger locomotives. Injectors work by blowing a jet of steam at high velocity through a flow of water imparting its velocity to the water. The combined jet is then moving fast enough to overcome boiler pressure and enter the boiler via the a one way valve (clack valve). A diagram and more details are available in the `I' section of the glossary.

Locomotive boiler water feed apparatus. Water in the boiler is consumed as steam is generated and it is essential that the water is replaced quickly to allow steam production to be maintained and to prevent too low a water level causing a collapse of the firebox crown.

Fuel injectors inject diesel fuel into the combustion chambers. The occurrence and quantity of the fuel injected can be controlled mechanically or electronically.