Modifications
The ED72 introduced a number of innovations over the previous series of EMUs. Amongst these was converting the rb (rear control cars) sections to first class units which were fitted with more comfortable seats, as well as new upholstery in the second class carriages. Double glazed windows were fitted; buttons for opening and closing the doors were installed — rather than having to wait for the driver to operate them; and matrix route manifests were installed, as opposed to the traditional blinds which only displayed the train's destination. The last unit to be produce — ED72-021 — is unique in that it has sliding doors that open outwards.
In terms of the unit's appearance, the major difference — apart from the red and yellow colour scheme — is the control car's frontal aspect. Furthermore, ED72s were originally equipped with single-arm pantographs, but most have been converted to using the traditional, diamond shaped, double-arm version.
The ED72's couplers allow it to be easily connected to other EMUs, and this is done quite frequently.
Read more about this topic: PKP Class ED72