Blue
The tractor air control valve? Stops air from flowing to trailer red air line. Safety switch incase trailer falls off truck all the air will not go out the broken hose and cause tractor spring brakes to lock up due to low air. It can be tested by disconnecting red air line while trailer brakes air released. Air should stop at about 30psi I think.
It's normally green, with the emergency air line being red, and the pigtail being blue. However, this is simply common practice, and not necessarily the rule - I've seen tractors with both lines black, and the glad hands would have "S" and "E" stamped on them.
It sounds like you have a bad head gasket.
Use a garden hose that is long enough to reach three corners of the trailer house from the fourth corner. Fill the hose with enough water so that the water can be seen from both ends of the hose (a short piece of clear tubing securely connected to either end of the hose would be helpful).Start at the first corner and hold the hose so that the water is level with the the bottom of the frame (or any feature that is at a common level at all parts of the trailer house).Secure the hose in place (or have one person hold it) and take the other end of the hose to the other three corners. Note the height of the water at the other three corners.Adjust each corner of the trailer house until the water is at the same level at all four corners.
The low side service port is on the suction side (larger hose) and the high side service port is on the discharge hose (smaller hose)......
green
You can visit Campbell Tractor & Implement at 2014 N Franklin Blvd. Nampa, ID 83687-6891.
color hose with navy dress & silver shoes
You can fill them with water. If you are in an area that freezes you will need to add anti freeze or a tractor dealership may have another additive. The tool to fill them attaches to a garden hose. Most dealerships sell them.
On the suction side only if you are just using a do it yourself kit........ The low side service port is on the suction side (larger hose) and the high side service port is on the discharge hose (smaller hose)......
In normal usage in an oxy/acetylene cutting torch, the acetylene hose is red and the oxygen hose is green.
There are 2 types of testing. Acceptance and Service. Acceptance testing is done by the manufacturer before it is shipped. Service testing is performed by the user periodically. Once a year. Service testing is for "in-service" hose to make sure it is maintained in optimum condition. Confirms that the hose is able to function at maximum pressure during firefighting operations. Guidelines are listed in NFPA 1962.