Bank engine

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The Lickey Banker 58100 "Big Bertha" assisting an express up the Lickey Incline, July or August 1955.

SZ Taurus pushing a freight train on the grade between Koper and Hrpelje-Kozina. An SZ class 363 is leading the train. July 2007.

A bank engine (United Kingdom/Australia) (colloquially a banker) or helper engine or pusher engine (North America) is a railway locomotive that temporarily assists a train that requires more power or traction to climb a grade (or bank). They are most commonly found in mountain divisions (called "helper districts" in the U.S.), where the ruling grade may demand the use of substantially greater motive power than that required for other grades within the division.

1 Application
2 Examples
3 Accidents
4 See also
5 Notes
6 External links

[edit] Application

Bankers or helpers were historically positioned at the rear of the train, in which case they also protected against wagons or coaches breaking away from the train and running back downhill. Also, in a pusher role, it was possible for the helper/banker to easily separate once the train had crested the grade. Once separated, the engine would return to a siding or stub so as to clear the mainline and get ready for the next train.

Since it was not possible to remotely control a steam locomotive, each helper/banker had to have a full crew on board. Careful coordination was required between engine crews to assure that all locomotives were operated in a consistent manner. Standard whistle signals were employed to tell the helper crew when to apply power, drift or brake. A misunderstanding of signals by a pusher locomotive crew could result in a major wreck if the lead locomotive applied brakes while the bank engine was still applying power. The usual result was that the train would experience a violent run-in (an abrupt bunching of train slack), resulting in the derailment of part or all of the train.

In modern practice, helpers/bankers are often placed in the middle of the train and are controlled by coded radio signals from the locomotive at the head end of the train, allowing one engineer (driver) to simultaneously control the helper(s) and main consist. This arrangement has the distinct advantage of applying the helper power to only part of the train, thus limiting the maximum drawbar pull applied to the first car of the train to a safe level. The Denver and Rio Grande Western Railroad, in particular, used "swing helpers," which meant the helper locomotives were placed mid-train at a point where they were pushing and pulling an approximately equal amount of tonnage, said location being referred to as the train's "swing point". However, this arrangement requires splitting the train in order to add or remove the bank engine(s) and therefore is not common where bank engines have to be added and removed quickly.

In countries where buffers-and-chain couplers are used, bank engines often cannot be added to the front of the train due to the limited strength of the couplers; in the UK it was a usual practice for banking locomotives to follow and buffer-up to a slow-moving assisted freight train without coupling (as demonstrated in archive films of banking on the Lickey Incline) before applying more power, thus avoiding a standing start. In the case of standard UIC couplers and a maximum grade of 28‰ (which is common e.g. for lines through the Alps), the limit is a train weight of 1400 tons^[1]; if a train is heavier, bank engines have to be added in the middle or to the end of the train in order not to exceed the maximum load for any coupler.

In the UK, an engine that was temporarily attached to the front of a train to assist with the ascent of an incline was called a pilot locomotive. This differentiated it from the train engine(s) which was provided to power the train to its destination. In Canada or the USA, a train with one or more helper locomotives attached to the head end would be referred to as a "double header," "triple header," etc., depending on the number of helpers/bankers. These terms gradually fell out of general usage as Diesel locomotives replaced steam power.

The town of Helper, Utah was named after these engines, as it was where helper engines were kept to assist on the climb to Soldier Summit.

Helpers/bankers were most widely used during the age of steam, especially in the American West, where significant grades are common and trains are long. The development of advanced braking systems and Diesel-electric or electric locomotives has eliminated the need for bankers/helpers in all but a few locations.

[edit] Examples

The following are locations where bankers are, or were, frequently required:

[edit] Australia

[edit] New South Wales

Willow Tree - Ardglen - 25‰ (1 in 40)
Murrurundi - Ardglen - 25‰ (1 in 40)
Cowan bank - 25‰ (1 in 40)
Tumulla - 25‰ (1 in 40)
Fassifern - 25‰ (1 in 40) - bank engine key interlocked with bank engine siding.
Bathurst - Kelso - 20‰ (1 in 50)
Lawrence Road - 20‰ (1 in 50)
Lithgow - Zig Zag - 24‰ (1 in 42)
Valley Heights - Katoomba - 20‰ (1 in 33)
Molong - Orange - 25‰ (1 in 40)
Picton Mittagong Loop Line - 30‰ (1 in 33)

[edit] Europe

Gotthard line - Frequent electric banking services for freight trains, SBB-CFF-FFS and others
Liège-Guillemins - Frequent banking of passenger trains heading towards Bruxelles.
Lötschberg line - Frequent electric banking services until the opening of the Lötschberg Base Tunnel in June 2007; future unknown yet; BLS, SBB-CFF-FFS and others
Monte Ceneri Pass line - Frequent electric banking services, SBB-CFF-FFS and others

[edit] Japan

Class EF63 locomotives for Usui Pass, Japan

"Senohachi" section (Seno - Hachihommatsu) of Sanyo Main Line - Dedicated EF67 electric locomotives assist heavy freight trains.
Usui Pass on the Shinetsu Line - The maximum grade of 6.67 percent necessitated the use of helper locomotives on all trains including EMUs, both uphill and downhill (for added braking ability). A pair of EF63 electric locomotives were connected to the downhill side of every train. This segment was closed upon the opening of the Nagano Shinkansen in 1997.

[edit] New Zealand

Reefton saddle on the Stillwater - Westport Line
Wellington and Manawatu Railway Company between Wellington and Paekakariki
Otira Tunnel, between Arthur's Pass and Otira on the Midland Line, after the removal of electrification

[edit] United Kingdom

The 'Long Drag' to Ais Gill Summit on the former Midland Railway Settle-Carlisle Line required the use of pilot engines in both directions during the steam era.
Beattock Bank on the former Caledonian Railway section of the West Coast Main Line. Prior to electrification banking engines were required for northbound trains (from Beattock station to Beattock Summit).
Cowlairs Bank, outside Glasgow Queen Street station is short but steep (24‰, or 1 in 42), and much of it is in a tunnel. Cable worked until 1909, the use of banking locomotives finally ended in the 1980s.
Druimuachdar Summit on the Highland Main Line
Ilfracombe branch line (28‰, or 1-in-36) – Steam until 1964
Falahill Bank on the northern part of the former North British Railway 'Waverley Route' (closed in 1969, but scheduled to reopen). Banking engines were required for southbound trains (from Hardengreen Junction, near Dalkeith, to Falahill Summit)
Lickey Incline, where banking of goods trains by EWS class 66 locomotives still occurs.
Peak Forest, Derbyshire – Steam then diesel until late 1980s
The Buxton Line in Derbyshire
Slochd Summit on the Highland Main Line
Whiteball Bank, Somerset
Whitrope Summit on the former North British Railway 'Waverley Route' (closed in 1969). Banking engines were employed in both the southbound direction (from Hawick), and northbound (from Newcastleton)
Worsbrough Bank, South Yorkshire – Steam until 1953 then Electric until 1981
Shap on the former London and North Western Railway section of the West Coast Main Line, required banking of northbound trains in the steam era