The ornamental design for a locomotive, as shown and described.
1. Locomotive
1.1 : Perspective
1.2 : Front
1.3 : Back
1.4 : Side view
1.5 : Top
An industrial design for a locomotive; it has a coach-type body that comprises a driver's cabin with rear-view mirrors on the right and on the left, a body frame with coupling devices mounted on locomotive bogies with wheel pairs, and a fuel tank located between the bogies.