To release trailer parking brake, push in trailer parking brake knob (1) located on trailer.
Remove chock blocks from trailer wheels, (Para 2-20).
The trailer spring brakes automatically apply when trailer reservoir pressure is low (below 40
psi [276 kPa]). The parking brake button will not stay pushed in when the pressure is low
unless the reservoir pressure is at "zero" pressure.
Apply. Pull out parking brake knob (1) located on trailer.