FS Class E.646

FS class E.646
E.646 in original livery
Type and origin Power type Electric Builder TIBB Build date 1958-1967
Specifications Configuration: ​  • UIC Bo-Bo-Bo Wheel diameter 1.250 m (49.21 in) Wheelbase 13.550 m (44 ft 5 1⁄2 in) between bogie pivots 2.580 m (8 ft 5 5⁄8 in) between axles on each bogie Length 18.290 m (60 ft 1⁄8 in) Width 3.013 m (9 ft 10 5⁄8 in) Height 4.296 m (14 ft 1 1⁄8 in) Loco weight 110–112 t (108–110 long tons; 121–123 short tons) Electric system(s) 3,000 V DC Catenary Current source Pantograph Traction motors DC Transmission 25/64 gear ratio Loco brake Oerlikon FV4 Safety systems RSC4; some units (about 40) have also been fitted with SCMT
Performance figures Maximum speed 140 km/h (87 mph) Power output hourly: 4,320 kW (5,790 hp) - continuous: 3,780 kW (5,070 hp) Tractive effort 233 kN (52,000 lbf)
Career Operators FS Trenitalia Number in class 198 First run 1958 Disposition Decommissioned in 2009

FS class E.645
Unit E.645.017 in its original livery
Type and origin Power type Electric Builder TIBB Build date 1957 – 1967
Specifications Configuration: ​  • UIC Bo-Bo-Bo Wheel diameter 1.250 m (49.21 in) Wheelbase 13.550 m (44 ft 5.5 in) between bogie pivots 2.580 m (8 ft 5.6 in) between axles in each bogie Length 18.250 m (59 ft 10.5 in) Width 3.013 m (9 ft 10.6 in) Height 4.296 m (14 ft 1.1 in) Loco weight 110–112 t (108–110 long tons; 121–123 short tons) Electric system(s) 3,000 V DC Catenary Current source Pantograph Traction motors DC series Transmission 21/68 gear ratio Safety systems RSC4
Performance figures Maximum speed 120 km/h (75 mph) Power output 3,780 kW (5,070 hp) Tractive effort 286 kN (64,000 lbf)
Career Operators FS Trenitalia Number in class 97 First run 1958 Disposition Decommissioned in 2009

The FS E.645 and E.646 are two classes of similar electric locomotives used on Italian railways. They were introduced during the 1950s and they were retired in 2009.

The E.646 and E.645 locomotives project was started in 1953, with a new model engine that was to be installed on the modified chassis of the already-existing six-axle locomotive E.636. A similar concept for a 4-axle locomotive led to the development of the E.444 high-speed locomotive in the 1960s.

The first prototypes were delivered in October 1958. The first thirty-seven individual locomotives differed only in their livery: twenty built for passenger traffic were painted in grey-green, while seventeen built for goods were painted in auburn. Later, the freight locomotives were reclassed E.645. The total number of locomotives built amounted to 295 units.

Several locomotives from each class are still in service with FS Trenitalia, on push-pull services, and many have been converted in E.645 and assigned to goods services until 2009. They are substituted by E.464 engines on regional services.

Class E.646 does not follow the standard Italian class numbering rules where the last digit indicates the number of motors, as it mounts 12 two by two mechanically coupled 82-333FS type electric motors, each providing 360 kilowatts (480 hp), fed from the 3000 V catenary. These motors are more powerful than those mounted on the predecessor E.636 class and able to improve performance up to 50% with only a 20% increase in weight; this also increases the mass available for adhesion, giving it better hauling ability.

Maximum speed is 140 km/h (87 mph) for the E.646. The E.645 has a different gear ratio — 21/68 instead of 25/64 — which reduces the maximum speed to 120 km/h (75 mph), while increasing tractive effort. The locomotives weights 110 t (108 long tons; 121 short tons) (E.645: 112).

To reach higher speeds, the motors can be electrically connected in four ways: