Скачать или смотреть [CSXT]2418 EMD SD40-2-Ex-CSXT-Ex-SBD-Ex-L&N 1058 EMD YD-SLG Ex-CO RE

A railroad slug is an accessory to a diesel-electric locomotive. It has trucks with traction motors but, unlike a B unit, is unable to move about under its own power, as it does not contain a prime mover to produce electricity, and there may or may not be a cab for an operator. Instead, it is connected to a locomotive, called the mother, which provides the needed electrical power to operate the traction motors, and the motor controls.Road slugs are intended to serve as part of a regular locomotive consist for road haulage, and as a result have certain adaptations to suit them for this service. They usually retain dynamic brakes, a feature useless at the low speeds encountered in switching service, and they may be equipped to serve as fuel tenders for the attached "mother" locomotives.

In operation, they are used to provide extra traction at low speeds. As speed increases they are disconnected from the power circuit and function as a control cab if they are in the lead, or simply as an unpowered car in the consist. In braking they augment the powered locomotives, both during dynamic and air brake application.

Road slugs may take several forms. A group of GP30 and GP35 locomotives were converted by CSX and operated as half of "mother-slug" pairs. Externally they retain the general appearance of powered diesel-electric locomotives, though they can be identified by the lack of radiators and the removal of most of the access doors on the side of the body. They retain the cab and its controls, and therefore multiple unit control allows them to function as the lead in a string of units. The TEBU units created on the Southern Pacific Railroad from General Electric U25Bs, on the other hand, were cabless; this potential operational deficiency was compensated for by putting them as the center unit of a set of three.

When at one end of a set, train crews will often go to great lengths to arrange for the slug to be the leading unit, as the lack of a diesel prime mover provides them with a quiet and vibration-free ride.
Road slugs are intended to serve as part of a regular locomotive consist for road haulage, and as a result have certain adaptations to suit them for this service. They usually retain dynamic brakes, a feature useless at the low speeds encountered in switching service, and they may be equipped to serve as fuel tenders for the attached "mother" locomotives.

In operation, they are used to provide extra traction at low speeds. As speed increases they are disconnected from the power circuit and function as a control cab if they are in the lead, or simply as an unpowered car in the consist. In braking they augment the powered locomotives, both during dynamic and air brake application.

Road slugs may take several forms. A group of GP30 and GP35 locomotives were converted by CSX and operated as half of "mother-slug" pairs. Externally they retain the general appearance of powered diesel-electric locomotives, though they can be identified by the lack of radiators and the removal of most of the access doors on the side of the body. They retain the cab and its controls, and therefore multiple unit control allows them to function as the lead in a string of units. The TEBU units created on the Southern Pacific Railroad from General Electric U25Bs, on the other hand, were cabless; this potential operational deficiency was compensated for by putting them as the center unit of a set of three.

When at one end of a set, train crews will often go to great lengths to arrange for the slug to be the leading unit, as the lack of a diesel prime mover provides them with a quiet and vibration-free ride.
Cows are analogous to A units and calves to B unit road locomotives. Both have prime movers. Like the early EMD FT locomotives, the Cow-calf sets were typically built as mated pairs, with the Cow (or cabbed unit) and calf (or cabless unit) sharing a number. However this was not always the case, with over time many of the sets being broken up and couplers added to aid with versatility.

Most cow-calf sets were built between the 1930s and the 1950s. They were built by several different makers, although General Motors' Electro-Motive Division built far more than the others. As originally constructed, the cow-calf units were typically used in hump yards where they spent much of their life pushing long trains over the hump for classification. There were, however, a few notable cases where this was not so, with some industrial railroads using non mated pairs as light road switcher locomotives. However, as with the larger three unit Cow-calf sets, such was very rare.

The cow-calf concept was adopted on Queensland 2 ft gauge sugar cane railways with two locomotives being coupled permanently in multiple-unit mode with the cab of one removed. This was utilised by Isis Mill (1980-1993) and by Mackay Sugar (2005)