Parry People Movers Ltd. (PPM) was a small British manufacturer of lightweight railcars that use flywheel energy storage for traction, allowing electric systems to operate without overhead wires or third rails.

It also designed concepts for trams and other rail technology using alternative fuels such as gas and hydrogen, but was not successful in finding further buyers among transport operators.

[3] This was abandoned after a series of mechanical and electrical failures and due to the unit proving to be unsuitable for the long and steep gradients on the line.

Prior to entry into commercial service, testing took place on the Severn Valley Railway in March and April 2002 with a PPM50 unit operating between Kidderminster and Bewdley.

A typical PPM flywheel is made from steel laminates, approximately 1 m (39 in) in diameter and 500 kg (1,100 lb) in mass, designed to rotate at a maximum speed of 2,500 rpm.

In April 2019, PPM announced plans to upgrade the original Class 999 PPM50 prototype with a diesel power unit and to seek approval for its entry into passenger service as 'No 139000'.