A. J. P. Wilding writes:— The lag in application of
Page 68
If you've noticed an error in this article please click here to report it so we can fix it.
the brakes was no doubt due to the particular layout of pipework. Changes made improved the situation somewhat but I agree that all too often modem brake systems are too sensitive to minor faults that develop. Changing the light/laden
valve was because of a fault on the original unit. It was not just a matter of resetting. But a wrong setting can give over braking (causing wheel locking) although the outfit may be at its maximum legal weight—even in this condition the trailer axles may not be carrying their design weight and to be correct, the maximum braking effort should only be attained in the maximum-load condition of the bogie. The job of the light/laden is to relate effort to the weight imposed and if the setting is such that the 10.8 tons braking effort needed to give 0.6g on an 18 ton bogie is produced for a 17 ton load, the balance is wrong and locking can result.