Clockers are essentially commuter trains operated between New York and Philadelphia under contract with NJ Transit. They accept NJT monthly passes in addition to Amtrak tickets. They run Amfleet coaches (no food service) and ALP-46 Locomotives on loan from NJ Transit. They make multiple stops on the NEC including: New York, Newark, Metropark, New Brunswick, Princeton Junction, Trenton, Cornwells Heights, North Philadelphia, and Philadelphia. NJT agreed to take them over by 2006, but opted to take them over now instead.
The Clockers date back to the Pennsylvania Railroad days and until a few years ago ran with Heritage equipment. The first Amtrak train to operate was a clocker: #235 (iirc) departed NYP at 12:05 AM on May 1, 1971