Air-compensated pintle hook air supply

I operate a boom truck for work. It's a straight truck. Occasionally we'll hook up a pup trailer. My truck has an air-compensated pintle hook that I use to hook up the pup trailer. It has an air chamber behind the hook that extends a snubber which presses against the lunette ring to eliminate slop within the hitch.

The other day I noticed that the air chamber is connected to the service air line instead of the supply (emergency) air line. As it is currently installed, the snubber only extends when I press the brake pedal. Under any prior experience I've had with these types of hitches, the air chamber has been connected to the emergency air line so that the snubber is in continuous contact with the lunette ring so long as the trailer air supply button is pushed in in the cab.

My dispatcher spoke with a mechanic at our local repair shop yesterday who assured him that the air chamber is currently installed properly; it's only supposed to extend the snubber when the brake pedal is pressed. He claimed that if the snubber were in continuous contact, it would prevent the trailer from turning easily, and it's only really needed when the brake pedal is pressed. Someone please tell me that this mechanic has no idea what he's talking about. This can't be right.

The air chamber on an air-compensated pintle hitch should be connected to the emergency air line so that the snubber is in continuous contact with the lunette ring. Right?

 

Thanks for these responses. Good to know I'm not losing my sanity more than I already am.