Geep
A nickname for the EMD GP series diesel locomotives.
Geep: the workhorse diesel that runs every railroad.
A geep is a diesel-electric locomotive built by Electro-Motive Division (EMD), usually a GP series model. The name comes from the phonetic pronunciation of the letters GP, which stands for General Purpose. These machines are the backbone of North American freight and switching operations, found on nearly every Class I railroad and hundreds of shortlines and regionals.
The GP series began with the GP7 in 1949 and evolved through the GP9 (1954), GP18 (1959), GP35 (1964), GP38 (1966), GP39 (1969), and GP40 (1971), among others. Early geeps produced around 1,500 to 1,800 horsepower; later models pushed 3,000 to 3,600 horsepower. They typically weigh 120 to 145 tons, making them lighter and more versatile than the larger road freight units. The Dash 2 and Dash 3 rebuilds of the 1970s and 1980s extended the lives of thousands of aging GP units.
Where geeps fit the work
A geep's real strength is flexibility. They handle switching in rail yards, local freight runs, and helper service on grades where they partner with other units. Unlike the long-hood-forward design of some freight engines, most geeps use a cab-forward layout that gives crews sightlines in both directions, crucial for yard work. A single geep can move 50 to 100 cars depending on tonnage, grade, and consist configuration.
Geeps run on 645 series diesel engines (most commonly the 16-645E3 or 20-645E3) paired with either a DC or AC electrical transmission. Maintenance crews know them inside out, and parts remain available despite their age. Many units built in the 1960s still operate today, rebuilt with modern fuel injection, turbochargers, and traction control systems. Radiator corrosion, fuel injector wear, and bearing degradation are the usual suspects in older geeps.
The term geep is pure railroad slang, used by dispatchers, engineers, and yard crews as shorthand across the industry. You will not find it in official Amtrak or Union Pacific documentation, yet everyone on the rail line knows exactly what you mean. It reflects how thoroughly the GP series conquered the market, making the model designation synonymous with the machine itself.