auxilary relief valve pressure

[longhauler]

I have a 4840 and use a Lorentz two stage snow blower to clear snow (don't like piles that add to the drift problem) My question is how do I up the pressure in the relief valve for the auxilary valve to keep the blower running at full capacity??? Can it be done externeraly?? I think it is under the cab on the right side of the machine. If some one could post a picture of the valve and directions for turning up the pressure it would be very helpful.