Belgian Railways Class 77

The NMBS/SNCB Class 77 (also known as HLD 77 or HLR 77) is a class of 4 axle B'B' road switcher diesel hydraulic locomotive designed for shunting and freight work manufactured at the beginning of the 2000s by Vossloh Schienentechnik/Vossloh Locomotives at the Maschinenbau Kiel plant in Kiel, Germany for the National Railway Company of Belgium (SNCB/NMBS).

Background and design
The initial order for 90 locomotives was given to Siemens in 1997 to replace an aging diesel fleet; the railway opted for a locomotive suitable for both shunting and mainline use, rather than separate classes. Siemens sold its locomotive manufacturer division (Siemens Schienenfahrzeugtechnik) to Vossloh in 1998.

The locomotives were variants of the standard MaK G 1200 series design, and are considered a development of the MaK G 1205 type. The locomotive is an off-centre cab design with a two-speed Voith hydraulic transmission driving all axles via cardan shafts. Auxiliary electrical supply is provided by an engine mounted alternator. Unlike many other MaK locomotives which use a MTU or CAT 12-cylinder V engine the locomotive has an ABC 6-cylinder inline engine.

The first locomotive was delivered in October 1999, and worked satisfactorily; a second order for 80 locomotives was given in June 2001.

Operations
The first locomotive entered service in February 2004. All 170 units were operational by June 2005.

Due to its relatively low power the locomotives work in multiple on heavy freight trains.

Equipment variations
Sets of the class vary in the type of equipment they carry: