Dividing Express Trains at Speed
AFTER THE SLIP. A Great Western Railway Bristol express just after it has detached the slip portion. The two detached coaches are running of their own accord into Bath Station. The London-
One objection to slip-
Nervous passengers sometimes were tearful that their carriage might be slipped at the moment when they were stepping through the vestibule gangway to or from the restaurant car; but due precautions were taken to avert such an eventuality.
Railwaymen of past generations always ascribed the original idea of the slip-
FRONT VIEW of slip coach, showing the slip hook open, the brake and steam-
JOINED TO THE TRAIN. The slip coach has the slip hook closed, and the couplings and brake and steam-
Formerly the couplings between the carriages were of the simple hook-
Here, however, was a valuable idea. It a carriage could be left behind by accident, and convey passengers safely to a station at which the train did not stop, why could it not be done deliberately and thus save delay? In a short time the slip-
The slip portion of a train is not limited to one coach only; so long as the coach with the slipping apparatus is placed next the “fixed” part of the train, the slip portion may be made up to any required length within certain limits. Neither is a train limited to one slip portion only; it necessary, a train could leave London for Glasgow or Edinburgh, for example, with fifteen coaches, and make a non-
There is no fundamental difference in construction between slip coaches and ordinary coaches. Any coach, so long as it has a guard’s compartment, may be fitted up for slipping by the replacement of the ordinary couplings by those of the detachable type; and ordinary coaches may be coupled in behind it without any alteration being necessary.
Slip couplings are of two types; in one, the draw-
The hinged shackle works on a fixed hook. It is very simple in action, and operates in precisely the same manner as a common snap padlock, with a catch held in the closed position by a spring. A stout cord or chain is attached to the catch; and on this being pulled by the guard, the shackle flies open (just as the padlock shackle does when the key is inserted and turned) and falls off the drawhook.
AT THE STARTING POINT. The slip coach is seen being coupled to the main train at Paddington Station. This is the rear slip on the “Cornish Riviera Express”; and the distinctive double tail-
THE SLIP HOOK (open) is about to receive the screw-
Readers have already seen, in the chapters on the brakes, that the brake hoses will uncouple of their own accord if they are pulled into a straight line, remaining coupled only while they hang down in a curve; so there is no difficulty in disconnecting brake pipes. As, however, the brakes would go on automatically in both parts of the train if the pipes were left open, provision has to be made for closing them. On some coaches fitted with air brakes, a small trap-
On some of the railways using vacuum brakes, cocks are provided on the ends of the hoses themselves, just behind the couplings. These cocks are made of gunmetal and fitted with a double-
When one coach only is slipped, the guard can stop it by applying the hand brake with which all brake vans are provided -
With the vacuum brake, the guard admits air to the train pipe for a brake application; to release brakes, he puts his handle to “release”, which immediately connects the train pipe with the highly exhausted vacuum cylinder. This extracts the air from the train pipe, and the brakes become released. As the slip-
MECHANISM OF THE SLIP. The diagram shows the way in which the slip lever pulls back the bolt that keeps the slip hook closed, and the method of uniting the vacuum brake couplings.
Great care is always taken in the manufacture and maintenance of the slip apparatus. It must not only be unfailing in its action, but it also has to operate on what one might term “split-
When attaching a slip-
When a slip is about to be made the slip guard, having satisfied himself that the signals are off, and that the train is running at the usual speed, applies the hand brake very slightly, to put a little “drag” on the coupling, closes the brake pipe cocks and releases the hook or shackle. He then applies his brake a little harder, and the two parts of the train separate. The train guard, as soon as he sees that the slip has been made successfully, gives the “all clear” to the engine driver, usually by showing his green flag -
On the Great Western Railway, one handle does all the work. To slip the coach, or portion of the train, the guard pulls the lever right back to “slip and brake on” position; this applies the vacuum brake on the slip portion, and releases the coupling and hoses, which are automatically sealed by spring valves as the pipes separate. He then puts the lever back to “brake released” position, which puts the train pipe in communication with the vacuum reservoir; the coaches then coast into platform, where a further movement of the lever to “brake on” brings them to rest.
THE SLIP GUARD looking out of his window at the end of the slip coach after he has operated the slip lever.
Special means are used to identify the slip portions of trains in a visible way. At the rear end of the slip, the coach carries two lamps side by side, one red and the other white, encircled by red and white disks for day use. If two slips are run on the same train, the inner one carries this distinctive tail signal, but the outer one carries the lamps one above the other. When the “Cornish Riviera Express” carried three slips, a special tail-
In abnormal conditions of traffic, when many expresses are run in two or more portions, the slip portion is often promoted to be an independent train. When this happens it is hauled to its destination in the usual way. The enlarged slip portion may itself slip one or more coaches on its journey.
[From part 21, published 21 June 1935]