Inspection of the Tractor-Protection Valve

My name is William Snow. I am a NYS Motor Vehicle Inspector, my office is in Syracuse New York. I have been in the program for a number years. I think you could say I am one of the "Old Timers". I have been doing inspections since 1987. Anyway, I was a mechanic also before I joined the program. I have seen a lot of changes in our program, good and bad. My question is about the TPV ( Tractor Protection Valve ). In the past few years, I have been fighting the change of the "Procedure" for checking the TPV. I feel I have a good reason. It is a safety AND quality issue. As you may or may not know, the TPV has two sides to it. A primary ( 60 psi ) "High" side and a secondary ( 30 psi ) or "Low" side. When I started the program we used to check BOTH sides of the valve. In the past few years the procedure changed. As of yet no one can tell me why the procedure changed. The original procedure was; 1. Make sure the wheels are chocked, vehicle in neutral and all brakes are released ( all systems charged ). The vehicle OFF. 2. Checked the air pressure, make sure the vehicle air pressure is at least 85 to 90 psi. BOTH sides ( primary and secondary ). 3. Now, remove the service hose to the trailer. ( blue side ). Leave the charge hose ( red side ) connected. Now by removing the service hose you have NO unregulated loss of air. So it is safe for you and the driver. Place the hose glad hand out of the way away in a safe place so it will not blow in any ones face. 4. Ask the drive to climb back into the cab ( if he is not in the cab already ). Make sure you are not in the way of the blast of air either. 5. Tell the driver to make a full brake application with his brake peddle, hold his foot until the air stops. 6. At this point unregulated air will escape from the service hose. Tell the drive to hold his foot on the brake peddle until the air stops. Once the air stops ( if air continues to leak until all the air is depleated from the vehicle, the low side of the valve is defective) check the glad hand and confirm no more air is escaping. At this point have the driver remove his foot from the brake peddle. ( This is a very important point I am trying to make. The service side of this test is the "Low" side of the system. The high side will shut or close at 60 psi. The low side will close at 30 psi. By doing this procedure the air pressure will drop to 30 psi ( or less ) There are TWO sides to this valve. If the HIGH side actives first it will take the low side out of the system. By checking the low side you automatically can check the high side. And do it safely, for both you and the driver. Also you will not injure or blow the rubber seal out of the glad hands. 7. Now go to the trailer and remove the CHARGE hose. You should not get any air. IF YOU DO, and you lose all the air, the high side of the valve is defective. 8. Now to complete the test, ask the driver to once again give you a full brake application, and hold his foot on the peddle. Now you can check ANY service brake. You must have enough air to activate ANY service brake on the vehicle. EVEN WITH 30 PSI OR LESS. After making this final check ask the driver to reattach the hoses to the trailer. The test is now complete. My point is, with the current procedure, once the "High" side of the valve activates the low side is taken right out of the test or system. You will never know if the low side of the valve is defective or not. In the years I have been doing this, I have found THE LOW SIDE defective. So with the current procedure the vehicle is good to go. With my procedure, you will find the DEFECTIVE VALVE! NOW WHEN YOU STOP A VEHICLE YOU USE THE BRAKE PEDDLE, CORRECT!! I have been questioning this ever since the procedure has changed. I have been to court and lost my case because of the current procedure. Does this seem right? I would like to thank you for any co operative with this matter.

Level of Importance. I believe that it would be very important. This is a safety issue for both the Inspector AND the industry.

Request for action, To change the existing proceedure for checking the Tractor Protection Valve.