The Bendix® RE-6NC™ relay emergency valve is a special non-charging RE-6™ relay emergency valve. It is used on dollies to comply with FMVSS 121. The RE-6NC™ valve eliminates the need for a protected reservoir to provide the release air for the trailer spring brakes when the following requirements are met:\n1. The trailer supply line must be 70 psi minimum with any leakage-type service system failure.\n2. The parking brake must not drag at trailer supply line pressures above 70 psi.The relay function of the RE-6NC™ valve is identical to that of the RE-6™ valve, serving the dolly or trailer system as a remote controlled brake valve. The emergency function of the valve automatically applies full trailer reservoir air pressure to the trailer or dolly chambers when the trailer supply pressure falls below a predetermined minimum value. The major difference between the RE-6™ and the RE-6NC™ valve is that the RE-6NC™ valve allows supply pressure (initial charge) to release the spring brakes before the dolly or trailer reservoir(s) is filled.