A standard diesel-electric locomotive that acts as the prime power source for a slug unit. The mother contains the diesel engine and main generator, routing excess electrical current to the traction motors of the engineless slug. This pairing maximizes tractive effort at low speeds without the expense of a second prime mover.
The yard job is using a mother and slug set to shove those heavy cuts over the hump.
Also heard as
- mate
Do not mix it up with
- Slug: The mother generates the power; the slug just uses it to provide extra traction.
Related terms
Slug
A heavy, motor-equipped unit without an engine that draws power from a coupled locomotive.
Yard slug
A low-profile, unpowered locomotive chassis equipped with traction motors to provide extra pulling force in a switching yard.
Traction motor
A heavy-duty electric motor geared directly to the axle of a locomotive or transit car.
Hump yard
A classification yard where cars are pushed over a small hill and roll by gravity into sorting tracks.