FS Class E656

FS class E.656

Unit E.656.569 in original livery

Type and origin Power type Electric Builder Officine Casaralta, Officine Reggiane, SOFER, TIBB componentistica Ercole Marelli, Ansaldo, Asgen, Italtrafo Build date 1975–1989 Total produced 459

Specifications Configuration: ​  • AAR B-B-B  • UIC Bo′Bo′Bo′ Gauge 1,435 mm (4 ft 8 1⁄2 in) standard gauge Wheel diameter 1,250 mm (49.21 in) Length 18.29 m (60 ft 1⁄8 in) Width 3.00 m (9 ft 10 1⁄8 in) Height 3.80 m (12 ft 5 5⁄8 in) Loco weight 120 t (118.1 long tons; 132.3 short tons) Electric system(s) 3,000 V DC Catenary Current source Pantograph Traction motors DC Safety systems RSC4; SCMT

Performance figures Maximum speed 150 km/h (93 mph) Power output Continuous: 4,200 kW (5,630 hp); One hour: 4,800 kW (6,440 hp) Tractive effort 249 kN (56,000 lbf)

Career Operators FS Trenitalia Nicknames "Caimano" (Caiman) Disposition In service

FS class E.655

E.655.166 Trenitalia Cargo

Type and origin Only differences from Class E656 above are shown Power type Electric

Specifications

Performance figures Maximum speed 120 km/h (75 mph) Tractive effort 300 kN (67,400 lbf)

The Class E.656 is an Italian articulated rheostatic-type electric locomotive built from 1975 to 1989. An evolution of the E.646, they are all-purpose locomotives, and have been used on every kind of train, ranging from freight to intercity passenger transport.

The E.656 is nicknamed "Caimano" (Caiman).

The hull is divided in two parts, each one with its own twin axle bogie, plus a central bogie in the middle. Each bogie mounts four DC motors, each providing 400 kW (540 hp), for a total of 12.

The initial project speed was 160 km/h (99 mph), but later it was reduced to 150 due to stability problems; further, the heavy mass of the locomotive did not allow the use of rheostatic braking.

Recently, many E.656s have been transferred to the Cargo Division of Trenitalia to haul freight trains. The gear ratio has been reduced from 28/61 to 23/66, and the speed limit to 120 km/h (75 mph). The modified units form the Class E.655.

The E.656 class is officially subdivided by FS into three series:

The differences between series regard electrical and mechanical equipment.

The 3rd series locomotives have four field weakening shunts in parallel and super-parallel motor combinations (where the other series have three), and the 78-wire cable to remote control the locomotive from a control car (Carrozza semipilota) or another Delfina-fitted locomotive.

Differences between locomotives can also be summed up as follows:

The locomotive has twelve 82/400 motors, with class B insulation, four per bogie.

They can be connected in the same combinations used on E.646:

Like their predecessors, E.656s have a rheostat (31 resistors subdivided in 21 packs, for a total resistance of 17,015 ohm) that, by varying its resistance, gradually regulates the current to the motors on starts, and on each time a transition to the next combination is made; however, differently from older Italian types, rheostatic exclusion is not controlled manually, by default.

The driver selects the desired combination, which is automatically accomplished by a system which, through a particular array of logic gates and other components (capacitors, resistors, etc.), called "RAE" (Relè Accelerazione Elettronico), controls a rotating device (called avviatore automatico). The driver selects the maximum exclusion current through a potentiometer on his desk, and the system, when the c.e.m.f. present in the motors brings the current (which is read by transducers) to a value lower than the set current, makes the avviatore advance, closing the rheostat contactors (thus shunting the relative resistors) as speed builds up, until it is totally excluded; similarly it may go backwards, when the current reaches high levels in relation to speed.