The New Zealand Railways Magazine, Volume 1, Issue 9 (February 25, 1927)
Modern Shunting Methods. — Gravity Shunting Yards—(Continued) — (Part VIII.—Hump Shunting.)
Gravity Shunting Yards—(Continued)
(Part VIII.—Hump Shunting.)
As shown in illustration No. 2 in my previous article, there are two main types of humps. As regards the engineering features of the grades no two yards are alike, and therefore no hard and fast rule can be laid down as to the most effective grade. Each yard must be built according to the types of wagons, weather conditions (including temperature and prevailing winds), general lay-out of points and crossings, and the distance wagons have to run to clearance points after leaving the hump.
In the colder climates such as are met with in America, either two humps are provided or the hump has a jacking device which provides a steeper grade when necessary.
With the English type of wagon it is generally recognised that the grade should be such that the speed of a wagon, after leaving the top of the hump does not exceed 10 to 12 miles per hour. With the introduction of mechanical track brakes this speed can be increased with safety, as any undue speed can be checked by these brakes.
The hump yard is, in effect, a flat yard with an artificial hump on the shunting leg so arranged that shunting engines instead of “setting back” at speed, stopping suddenly, and then pulling ahead again, merely push the wagons over the hump at a steady speed of about two miles per hour. As soon as the detached wagons arrive at the top of the hump they fall away from the train. Providing the grade is correctly set and the speed of the train is suitably adjusted, a train of 70 wagons or so can be passed over the hump and the wagons marshalled into their respective roads without the engine coming to rest.
It can be seen that the advantages of using an artificial hump in place of a flat shunting neck are considerable. Firstly the average time to make one cut or shunt in a modern hump yard with mechanical points operation is approximately 22 seconds, that is to say, a 70 wagon train with 50 cuts can be split up in 18 to 20 minutes. Contrast this with, at the very least, one hour for the same work with flat shunting. I have in mind a yard where, with the construction of a hump, the same traffic is handled with a reduction of 13 engine hours each day. In New Zealand this would represent a saving of over £2,000 per annum. I can imagine some of my shunter readers wishing they had a few humps in some of our shunting yards on a busy night.
Secondly, there is a considerable reduction in the cost of operating the locomotive as the work performed is much less, and the wear and tear on the brakes and draw gear is reduced to a minimum.
Thirdly, as explained in regard to “all gravity” yards, the damage to rolling stock and freight by constant jerking is eliminated.
Fourthly, the shunting staff can be greatly reduced; in fact, with electrical points operation and mechanical track brakes, the work of the ground staff on the hump is confined solely to receiving incoming trains preparatory to passing them over the hump, the actual movement on the hump being controlled by one signalman and the track brake operators located in towers at convenient points.
This refers to the most modern yard. The usual. method is for brakemen to be stationed in the yard to steady the wagons as they run down from the hump. In America as many as 40 men are required at one time for this service, and a special track is provided to bring them back to the hump on motor jiggers. As previously explained, this is due to the brakes being on the top of wagons, necessitating men riding with each cut.
Taking everything into consideration it can be seen that hump shunting offers very considerable advantages over flat shunting in large yards. The hump method is, however, only considered economical when handling 500 or more wagons per day.
Method of Operating a Hump Yard where
Points are Electrically Controlled.
On the arrival of a train in the reception sidings the engine is released and sent to the loco. depot or to the departure sidings as the case may be. Shunters uncouple the wagons where cuts are to be made and chalk either on the front of the leading wagon of each cut or on the back of the last wagon (according to the method of working) the number of the Toad to which the cut is to be shunted. The “pusher” or hump shunting engine then backs on to the train and, at a given signal, proceeds to push the wagons over the hump at a speed of about 2 miles per hour. The signalman operating the points by means of push buttons—as shown in Illustration No. 1—presses the button corresponding to the number of the road he sees chalked on the wagons as they pass him. Some railways prefer the number on the trailing ends of the wagons to ensure that the signalman is always looking towards the yard.
In the event of wagons not running down and thereby fouling other roads an indication by means of tract circuiting is immediately given to the signalman and he can stop the hump engine by means of Claxon horns, by loud speakers situated at various convenient points, or by electrically operated signals giving different aspects indicating go slow, stop, go ahead, etc.
The last wagons having passed over the hump, the hump engine either returns back over the road upon which it has been working to the other end of the reception siding—preparatory to pushing another train over the hump—or it continues over the hump in order to “trim” the marshalling sidings—that is to say, to close up all the wagons in each road and thus make room for more.
In the American yards where car retarders are now increasingly used, the operators receive shunting lists which show them the nature of each cut, whether loaded or empty wagons, the gross load, and the road into which they are to be shunted. This enables the operators to adjust their brakes to a nicety and with practice the bringing of a “cut” to a standstill against other wagons without shock is reduced to a fine art. In England the practice up to the present has been to use the brakesman to drop the brakes as required. In some yards brake shoes are used. These are placed on the rails and carried along by the wagons. As a stopping device they are extraordinarily effective. In the latest hump yard in France (at Lille) there is installed a very ingenious device and one much less costly than track retarders. This is, in effect, a brake-shoe, but page 50 is so arranged that it travels on a guide parallel to the rails and, after braking the wagons a certain distance, becomes detached from the wheel and returns to its starting point ready to brake another wagon.
As an illustration of the economics to be effected by hump shunting the case of Wath, England, is of interest. This yard handles with two engines, each working 24 hours per day, 13,000 wagons per month over two humps, one for the “up” traffic and one for the “down.” As many as 6,000 wagons have passed over the two humps in one day. The shunting staff for each hump consists of three head shunters, twelve shunters, three signalmen and three inspectors. The multiples of three indicate that the yard works 24 hours (three eight hour shifts). The marshalling is of such a nature that all work is done from the hump end of each yard. No sorting or making up of trains is required. This therefore serves as a good instance of the output per man and per engine when shunting with the aid of a hump.
A correspondent, writing from Toronto, draws attention to the great strides made by radio both in Canada and the United States. “The politicians of the latter,” he states, “keep in touch with distant supporters, and the isolated Canadian settler or miner retains contact with the world. The Governments of both countries control and support the business. Every kind of musical programme, sermons, and addresses are put on the air C.F.C.A. (The Toronto Star) picks up and broadeasts communications from all sorts of distant places (I have not heard of any from New Zealand yet) as well as keeping a regular programme locally.”page 51