motors

It can, if the windings are switched differently from a series connection, because to regenerate with this type of motor requires a stator field, best provided by switching the motor into parallel.

London Underground once had a wonderful type of DC brake called the Metadyne. It had the curious feature of being able to brake a train at the maximum adhesion available at the rail head. The motors were connected so that one motor generating powered another motor in reverse and in so doing the vehicle lost kinetic energy at the maximum rate that adhesion would allow, i.e. without wheelslip (yep - think about it, it works........). It was usually controlled by switching series resistance between the motors in and out. In fact, it was such a good brake that drivers were soon forbidden to use it for fear of all the standing passengers ending up with their noses pressed against the driver's cab's door and the rest of them in a pile on the floor underneath them.....