Can anyone advise what guages should read as both mine read at 7 it sounds as though the 'compressor' may not be at full capacity as sounds 'knocky' although that is just a stab at diagnostics any firm advice really greatly received.
Brakes feel ok
Martin

martin shepherd, March 2008

both gauges should be at 10 to 11 on the reading..the compressor should cut out at about 11 on the gauge and it should start to work at about 9 at the lowest pressure..you will proberbly find the air switch under the cab near the gearstick is not adjusted properly

jason, June 2008

You need at least 100 psi to operate the brakes effectively.
The low pressure warning buzzer will come on when you start up if pressure is less than about 70 psi and will only stop buzzing above 70 psi. The brakes won't release if the pressure in the reservoirs has not built up.
The fact that both gauges have the same , low reading suggests:
( and this is a quote from the Ford Cargo workshop Manual)
"(a) Air leak in supply circuit from compressor.
(b) Faulty air limiter valve.
(c) Faulty safety valve - blowing off continuously.
(d) Restriction in compressor output circuit.
(e)Restruction in compressor air intake.
(f) Faulty compressor."

JD, March 2008