M1078 Drives Through Brakes

[Coffey1]

I always had 120psi or over on primary secondary and wet tank.
But that check valve would not let my front brakes work

 

[AmbitionStrikes]

@Coffey1 Now you got me thinking.

From studying the schematic I can see that the purpose of the check valve you are referring to is to prevent air from feeding back through the front service glad handle to the pedal valve. So, if that check valve were stuck it could easily prevent air from reaching the front service brakes from the pedal valve.

I took a pressure reading at the output of front quick change valve (this is the line going directly to a brake chamber). Apply the brakes and the pressure matches whatever the pressure in the primary tank is. So, I know the check valve is not blocking air to the front brakes. However, the pressure gauge requires very little volume. As I typed this I realized that the check valve could be restricting VOLUME to the front brakes. It certainly could be worth taking that valve apart and seeing how it looks.

Thanks!

 

[Ronmar]

@Coffey1 Now you got me thinking.

From studying the schematic I can see that the purpose of the check valve you are referring to is to prevent air from feeding back through the front service glad handle to the pedal valve. So, if that check valve were stuck it could easily prevent air from reaching the front service brakes from the pedal valve.

I took a pressure reading at the output of front quick change valve (this is the line going directly to a brake chamber). Apply the brakes and the pressure matches whatever the pressure in the primary tank is. So, I know the check valve is not blocking air to the front brakes. However, the pressure gauge requires very little volume. As I typed this I realized that the check valve could be restricting VOLUME to the front brakes. It certainly could be worth taking that valve apart and seeing how it looks.

Thanks!

A restricted pathway would delay braking force, but not prevent it. If you held steady pedal, the cans would fill to the delivered pressure eventually and provide the associated braking force for that pressure. Of course the quick check for volume is to simply disconnect the line at the can, hold on to it and note the amount of flow when someone steps on the brake pedal...

dod you check that the vents on the cans are clear?