F ollowing the 1983 braking regulations all semi-trailers must have either
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an anti-lock system or a load-apportioning valve in the braking circuit. Many fleet engineers went down the load-apportioning valve route for their new trailers but there are still a lot who plumped for ABS.
The most popular ABS system fitted to semi-trailers in the UK has been known by various names starting with Girling Skidcheck and now known as the Grau MGX2.
MGX was launched in 1983 and the MGX2 version superseded it in 1986. On last year's figures there are over 75,000 MGX units in service. With such a large number of units in the field and the prospect of mandatory ABS on trailers in 1991 Workshop went to see how the fault finding process is carried out.
We went along to Grau's training centre in Blackburn to meet Martin Atkinson, one of the company's 'regional service engineers, who explained the procedure.
The procedure described here is suitable only for semi-trailers with single module systems (one axle sensed) using MGX1 (Blue casing) or MGX2 (black casing). Anyone who follows this procedure and still cannot trace the fault should contact Grau's technical services department on (0527) 510310.
Our thanks to Grau and to Wheelbase for the use of a partly built trailer for photography.
by Cohn Sowman