3551 to 3560
- Axle: 1'C1't
- Total quantity: 10
- First year: 1911/12
- Manufacturer: Maffei. Works Numbers 3278-83 (1911), 3342-45 (1912)
- Ex CO Numbers 331-340
Initially, these engines were used on commuter trains between Sirkeci and Halkali up until the electrification of that segment in 1955.
Pictures
3555,İstanbul Yedikule, 26th August 1955. Photo Alan Swale | 
3557, İstanbul Yedikule, 26th August 1955. Photo Alan Swale |
3559 ex CO 339 (Maffei 1912/3344). Afyon; 6 May 1974. Photo Benno Bickel | 
3556 at Samsun 31 March 1974. Photo Robin Lush |
3558 Çamlık museum, 1995, photo Peter Crush |
Engine main characteristics
| Engine axle type | 1'C1't |
| Driving wheel dia | 1410 mm |
| Front bissel wheel dia | 1010 mm |
| Rear bissel wheel dia | 1010 mm |
| Number of cylinder | 2 |
| Cylinder dia | 500 mm |
| Piston stroke | 630 mm |
| Boiler pressure | 12 bar |
| Grate surface | 2,75 m2 |
| Heating surface | 165,7 m2 |
| Fixed wheel base length | 3,7 m |
| Coupled wheel base length | 3,7 m |
| Overall wheel base | 8,9 m |
| Weight empty | 57,5 T |
| Weight loaded | 77,5 T |
| Adhesion weight | 49,2 T |
| Load per driving wheel | 16,4 T |
| Water capacity | 11 m3 |
| Coal capacity | 3,5 T |
| Overall length | 13,03 m |
| Max speed | 70 km/h |
| Tractive effort | 10,05 T |