Slip Brake testing
|A long standing method of measuring the
braking performance of a vehicle was slip brake testing.
This had been done for a number of years and from the early 1970's the Testing Section always carried out their tests under a total possession on the Down Slow line near Winsford, north of Crewe on the WCML.
This line was straight and level and the train could propel back to the starting point as required during the tests. Altogether an ideal site for braking tests and once completed the train would go forward to Warrington where the loco would run round then head for home.
On the formation of the RTC the test vehicle used for such tests was the former Eastern Region Dynamometer Car No:2, later DB999500 which was inherited from the York CM&EE and became Test Car 2. It was modified with a specially-piped independent braking system and fitted with a slip coupling on the rear.
It had an unfortunate demise in an accident on slip brake testing work in 1974 when the vehicle under test failed to stop and collided with the Test Car at low speed. Fortunately nobody was seriously injured, just shaken but the Dynamometer Car suffered irreparable damage to its sensitive and integral instrumentation. It was dumped at Crewe Coal yard for a number of months before being cut up on site.
Latterly a new Test Car 2 was used. Numerous tests were conducted over the last 25 years on freight and passenger vehicles, tare and laden at various speeds
There's an interesting article by Steve Morris of Ty Mawr Publications here which has a number of photos of slip testing and includes latter day testing on the Great Central Railway, Loughborough
Some photos from 1986
Click on the picture for a bigger image - photos are courtesy Dave Bower
|Class 47 with Test Car 2 and the test vehicle approaching the site|
|Propelling back to pick up the wagon|
Here are a series of photos depicting a typical slip and brake test on a bogie hopper wagon on 13th July 1999
Click on the picture for a bigger image - photos are the author's
|Class 47 with Test Car 2 and the test vehicle approaching the site - just past the bridge in the above photo - 13 years later!|
|The power is eased off and the slip coupling pulled. The photo shows the moment after separation|
|The Test Car and locomotive continue unbraked and the test vehicle has now had the brake automatically applied by the separation of the brake pipe - note the safety lights on the test vehicle which flashed alternatively as long as the vehicle was moving|
|The vehicles continue along the line|
|After the test vehicle comes to a stop the train is propelled to the stopping point in order to collect the vehicle|
|The engineers now have the
opportunity the check the instrumentation, brake disc temperatures etc
Once all is re-coupled the test train propels back to the starting point and the test is repeated
More pictures will be added as time permits
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