Rhaetian Railway Gem 4/4
Rebuilt Gem 4/4 802 at Pontresina, 2010.
Type and origin Power type Electro-diesel Builder SLM, SWS, BBC, and MFO Build date 1966 Total produced 2
Specifications Configuration: ​  • UIC Bo′Bo′ Gauge 1,000 mm (3 ft 3+3⁄8 in) metre gauge Wheelbase 2,200 mm (7 ft 3 in) Length 13,540 mm (44 ft 5 in) Width 2,700 mm (8 ft 10 in) Height 3,820 mm (12 ft 6 in) Loco weight 50 tonnes (49.2 long tons; 55.1 short tons) Fuel type Diesel fuel Electric system/s 1,000 V DC Overhead Current pickup(s) Pantograph Engine type Four stroke diesel engine Traction motors 4 (type EMR 475-wound)
Performance figures Maximum speed 65 km/h (40 mph) Power output Electric: 560 kW (750 hp) Diesel: 780 kW (1,050 hp) Tractive effort 80 kN (17,980 lbf)
Career Operators Rhaetian Railway Numbers 801–802 Locale Graubünden, Switzerland Delivered 1966 Disposition Both still in service

The Rhaetian Railway Gem 4/4 is a two member class of metre gauge Bo′Bo′ electro-diesel locomotives operated since 1968 by the Rhaetian Railway (RhB), which is the main railway network in the Canton of Graubünden, Switzerland.

The class is so named under the Swiss locomotive and railcar classification system. According to that system, Gem 4/4 denotes a narrow gauge electro-diesel engined adhesion locomotive with a total of four axles, all of which are drive axles.

The companies involved in building the Gem 4/4s were the Swiss Locomotive and Machine Works (SLM), Schweizerische Wagons- und Aufzügefabrik AG Schlieren-Zürich (SWS), Brown, Boveri & Cie (BBC) and Maschinenfabrik Oerlikon (MFO). The power output of the Gem 4/4s at the wheels is 780 kilowatts (1,050 hp) in diesel operation, and 680 kilowatts (910 hp) under the DC wires.

Closely related to the Gem 4/4s are the two HGm 4/4s that were delivered a year later to the Furka Oberalp Bahn.

Technical details

Liveries

At the time of their commissioning, the Gem 4/4s were painted red with silver ventilation grilles. Between 1986 and 1987, the livery was revised as follows: grey-brown frame, red body with bilingual logo and the cantonal shield of Graubünden.

Since the Gem 4/4s were rebuilt, they have remained in red livery. The two locomotives can be distinguished by their silver side-mounted logos: no 801 is fitted with an ibex (Steinbock), and no 802 is decorated with a marmot (Murmeltier).

Operational deployment

Unrebuilt Gem 4/4 802 above Lago Bianco, 1980s.

Ever since the Gem 4/4 electro-diesels were commissioned, their main area of operation has been the Bernina Railway, where they are often to be seen working in a multiple unit combination with railcars. In addition, they operate construction trains and snow clearing services throughout the Rhaetian Railway network.

Between 1973 and 1981, both Gem 4/4s were reserved each summer for the haulage of the Bernina Express. They would take over the Tirano-bound through coaches in Samedan from the St Moritz express train, and then pilot them in diesel operation to Surovas or Bernina Diavolezza, where the Gem 4/4 would be switched to DC electric operation. Thereafter, the Gem 4/4 would lead the Bernina Express further, to Tirano. Today, this form of operation would be regarded as hybrid traction.

Ever since the installation in 1981 of a switchable catenary section above track 3 at Pontresina station, the Bernina Express through coaches from Chur have been hauled as far as Pontresina by a core network electric locomotive powered by 11 kV AC current. After the train stops in Pontresina, the core network locomotive is uncoupled, and the catenary section is switched to 1,000 V DC. A Bernina Railway railcar train is then manoeuvred onto the existing train. The rolling stock so added is usually made up of ABe 4/4 II or ABe 4/4 III railcars, sometimes mixed with a Gem 4/4. At the conclusion of the timetabled seven-minute halt in Pontresina, the train continues further under the DC wires and over the Bernina Pass towards Tirano.

List of locomotives

See also

• History of rail transport in Switzerland
• Rail transport in Switzerland

References

Wikimedia Commons has media related to RhB Gem 4/4.

• Belloncle, Patrick (2005). Das grosse Buch der Rhätischen Bahn: 1889–2001 [The Big Book of the Rhaetian Railway: 1889–2001]. Kerzers: Edition Viafer. ISBN 3952249408. (in German)
• Finke, Wolfgang; Schweers, Hans (1998). Die Fahrzeuge der Rhätischen Bahn. Band 3 Lokomotiven, Triebwagen, Traktoren 1889–1998 [The Motive Power of the Rhaetian Railway Vol 3 Locomotives, Railcars, Tractors 1889–1998]. Aachen: Verlag Schweers + Wall. ISBN 3894941057. (in German)
• Kröpfli, Eric (June 2001). "Die Modernisierung der Zweikraftlokomotiven Gem 4/4 801-802 der Rhätischen Bahn". Schweizer Eisenbahn-Revue (in German).
• Schönborn, Hans-Bernhard (2009). Die Rhätische Bahn Geschichte und Gegenwart [The Rhaetian Railway History and Present]. München: GeraMond. ISBN 9783765471629. (in German)