| Class Y 7100 | |
| Powertype: | Diesel |
| Builder: |  Billard Decauville |
| Builddate: | 1958–1962 |
| Totalproduction: | 210 |
| Uicclass: | B |
| Driverdiameter: | 1050mm |
| Wheelbase: | 3685mm |
| Length: | 9.94m (32.61feet) |
| Locoweight: | 32t |
| Fueltype: | Diesel |
| Primemover: | Poyaud 6PYT |
| Enginetype: | Diesel |
| Transmission: | Hydraulic |
| Maxspeed: | 54km/h |
| Poweroutput: | 150kW |
| Tractiveeffort: | 73kN |
| Operator: | SNCF |
| Operatorclass: | Y7100 |
| Fleetnumbers: | Y7101–Y7310 |
The Y 7100 class of small shunters originally had 210 members. The first 130 were built by Billard, with the remaining 80 by Decauville. They have the 0-4-0 ("B") wheel arrangement, 150 kW diesel engines and hydraulic transmission. They can be found all over the French network.
Y 7192 was converted to mechanical transmission and renumbered as Y 7001. This locomotive was the prototype for the Y7400 class.
In addition to SNCF, VLFI have purchased four Y 7100 locomotives (numbers 7172, 7200, 7214 & 7245) from SNCF. two further locos are recorded in use in the Port of Rouen (Grand port maritime de Rouen french).
Some of them are preserved by touristic railroads.