The Great Central Heritage Railway is home to Test Car 2, an Ex BR Mk1 BSK number 35386, converted in 1974 by Derby DM&EE. It was mainly used for slip brake testing on the West Coast Main Line and testing Class 92 locos in 1994 on WCML & through the Channel Tunnel. It was open for visitors at the recent Great Central Gala weekend
Modifications includes a workshop area, generator and compressor, instrument area and mess facilities.
Slip testing of coach and wagon brakes used a section of the WCML Down Slow line between Crewe & Winsford under T3 possession. The train consisted of the loco, Test Car 2 & the vehicle under test. When the train reached the test site loco power was shut off, a special slip coupling was operated from the coach and the wagon brakes were applied, A decelerometer on the wagon under test attached to a red light indicated when the wagon had stopped. The rest of the train then stopped, and the wagon stopping distance calculated, remaining air pressure in the tank checked and readings of deceleration taken. The train was reversed and recoupled to the wagon.
Test Car 2 was retired in 2011 & moved to the Great Central Railway in 2016. Since then it’s been restored & displays created to tell the story of slip testing. More info on the Quorn Wagon group site, including details of their other rolling stock (Thanks to Quorn wagon page for images)
Dave Bowers, who worked with the coach & is now involved in the restoration team, has a very detailed book on Rail Vehicle Testing available.