unclebilly Posted February 4, 2012 Share Posted February 4, 2012 Is the tractor park valve supposed to be spring loaded?Mine had a slight leak so I bought a new valve to replace it. Unfortunately, the dealer gave me a trailer supply valve.I took both valves apart and used the o-rings and disk from the new tractor supply valve to fix my tractor park valve.I think some genius may have tried to fis my tractor park valve before with aviation form a gasket. Quote Link to comment https://www.bigmacktrucks.com/topic/23061-tractor-park-valve-the-blue-one/ Share on other sites More sharing options...
Rob Posted February 5, 2012 Share Posted February 5, 2012 Is the tractor park valve supposed to be spring loaded?Mine had a slight leak so I bought a new valve to replace it. Unfortunately, the dealer gave me a trailer supply valve.I took both valves apart and used the o-rings and disk from the new tractor supply valve to fix my tractor park valve.I think some genius may have tried to fis my tractor park valve before with aviation form a gasket.I've seen them both ways. I like the ones that are not spring loaded as I only have to mash the brake release button instead of both of them.Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/23061-tractor-park-valve-the-blue-one/#findComment-100993 Share on other sites More sharing options...
Green Dash Posted February 5, 2012 Share Posted February 5, 2012 I've only driven 3 trucks with the third "blue" knob and that was how they worked. It became inactive when the yellow knob was pushed and you technicaaly did not have to use the blue knob at all. Quote Jim Link to comment https://www.bigmacktrucks.com/topic/23061-tractor-park-valve-the-blue-one/#findComment-101002 Share on other sites More sharing options...
umodelnut Posted February 5, 2012 Share Posted February 5, 2012 my u model has a blue nob but it dont work cause you can pull it in or out and nothing not even a sound happens. Quote Link to comment https://www.bigmacktrucks.com/topic/23061-tractor-park-valve-the-blue-one/#findComment-101004 Share on other sites More sharing options...
Rob Posted February 5, 2012 Share Posted February 5, 2012 I have four trucks with the blue knob and they are spring loaded. If the yellow knob is pulled out, (setting parking brakes) the blue knob has no pressure. To move the tractor you have to push both the yellow which charges the port for the blue valve, then push the blue knob to release the tractor brakes. If you push the yellow only, the tractor brakes do not release.Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/23061-tractor-park-valve-the-blue-one/#findComment-101008 Share on other sites More sharing options...
Red Rover Posted February 5, 2012 Share Posted February 5, 2012 All I got is a wig wag and a hand brake. All this talk of spring loaded buttons of different colors sounds confusing. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/23061-tractor-park-valve-the-blue-one/#findComment-101012 Share on other sites More sharing options...
Green Dash Posted February 5, 2012 Share Posted February 5, 2012 I have four trucks with the blue knob and they are spring loaded. If the yellow knob is pulled out, (setting parking brakes) the blue knob has no pressure. To move the tractor you have to push both the yellow which charges the port for the blue valve, then push the blue knob to release the tractor brakes. If you push the yellow only, the tractor brakes do not release.RobThat's definitely different from the few that I drove. You could set the tractor brakes using the blue knob or the yellow knob. Having no prior experience with this setup, I wondered why the blue knob was even there. All 3 trucks had there cabs replaced which makes me think that possibly something was changed in the process??? Quote Jim Link to comment https://www.bigmacktrucks.com/topic/23061-tractor-park-valve-the-blue-one/#findComment-101015 Share on other sites More sharing options...
jaysm35a2 Posted February 5, 2012 Share Posted February 5, 2012 That wig wags truckin! Ive always wanted one in a truck. Quote Link to comment https://www.bigmacktrucks.com/topic/23061-tractor-park-valve-the-blue-one/#findComment-101017 Share on other sites More sharing options...
unclebilly Posted February 5, 2012 Author Share Posted February 5, 2012 (edited) I've only driven 3 trucks with the third "blue" knob and that was how they worked. It became inactive when the yellow knob was pushed and you technicaaly did not have to use the blue knob at all.This is how my truck is. I never use the blue nob but it did have a slight leak so I decided to fix it. I guess if I put a spring in it, I have to use it. If I leave the spring out, I can just use the yellow knob. Edited February 5, 2012 by unclebilly Quote Link to comment https://www.bigmacktrucks.com/topic/23061-tractor-park-valve-the-blue-one/#findComment-101023 Share on other sites More sharing options...
randyp Posted February 5, 2012 Share Posted February 5, 2012 I have four trucks with the blue knob and they are spring loaded. If the yellow knob is pulled out, (setting parking brakes) the blue knob has no pressure. To move the tractor you have to push both the yellow which charges the port for the blue valve, then push the blue knob to release the tractor brakes. If you push the yellow only, the tractor brakes do not release.RobTrue here also Rob,,,,randyp Quote Link to comment https://www.bigmacktrucks.com/topic/23061-tractor-park-valve-the-blue-one/#findComment-101025 Share on other sites More sharing options...
randyp Posted February 5, 2012 Share Posted February 5, 2012 All I got is a wig wag and a hand brake. All this talk of spring loaded buttons of different colors sounds confusing.I miss the wig wag days,,,life was so much simpler,,,,randyp Quote Link to comment https://www.bigmacktrucks.com/topic/23061-tractor-park-valve-the-blue-one/#findComment-101026 Share on other sites More sharing options...
fifth wheel Posted February 5, 2012 Share Posted February 5, 2012 With air lines attached to a trailer,Red charges the trailerYellow sets and releases tractor and trailer brakesBlue sets and releases tractor brakesYellow overides the blueBlue is not spring loadedFW Quote Link to comment https://www.bigmacktrucks.com/topic/23061-tractor-park-valve-the-blue-one/#findComment-101030 Share on other sites More sharing options...
Red Rover Posted February 5, 2012 Share Posted February 5, 2012 I agree , but there is something reassuring in the back of your mind in knowing that if the worst happens, all those spring loaded knobs will pop and whatever brakes you have will be on. Quote Link to comment https://www.bigmacktrucks.com/topic/23061-tractor-park-valve-the-blue-one/#findComment-101031 Share on other sites More sharing options...
Rob Posted February 5, 2012 Share Posted February 5, 2012 With air lines attached to a trailer,Red charges the trailerYellow sets and releases tractor and trailer brakesBlue sets and releases tractor brakesYellow overides the blueBlue is not spring loadedFWMy blue knobs are and will not stay depressed unless the yellow knob is pushed in. The blue knobs will pop back out with no air in the tanks, or the yellow knob is out. If the yellow, and the blue knobs are depressed, the tractor spring brakes are released and the tractor can be driven. If you pull the yellow knob to set the spring parking brakes, the blue knob will also pop out. When the tanks are above about 45psi and the yellow knob pressed in the tractors will not move until the blue knobs are pushed in.Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/23061-tractor-park-valve-the-blue-one/#findComment-101042 Share on other sites More sharing options...
randyp Posted February 5, 2012 Share Posted February 5, 2012 correctamundo Lt. Rob, thas my story and im sticky in it,,,,randyp Quote Link to comment https://www.bigmacktrucks.com/topic/23061-tractor-park-valve-the-blue-one/#findComment-101081 Share on other sites More sharing options...
storkmack Posted February 5, 2012 Share Posted February 5, 2012 Around here, we say that real trucks have 3 buttons. Dad always ordered the few new Macks we have had with three buttons until that wasn't an option any more. I think that the blue button went to the way side in 01' with the new style dash. I use the blue button a lot. Use them if you got'em. - Brad Quote Link to comment https://www.bigmacktrucks.com/topic/23061-tractor-park-valve-the-blue-one/#findComment-101117 Share on other sites More sharing options...
fifth wheel Posted February 5, 2012 Share Posted February 5, 2012 You need the three button setup for frameless dump trailer work.FW Quote Link to comment https://www.bigmacktrucks.com/topic/23061-tractor-park-valve-the-blue-one/#findComment-101118 Share on other sites More sharing options...
shortstack Posted February 5, 2012 Share Posted February 5, 2012 Now I'm confused. I've got a frameless dump trailer and I'm a button short! Trey Quote Link to comment https://www.bigmacktrucks.com/topic/23061-tractor-park-valve-the-blue-one/#findComment-101120 Share on other sites More sharing options...
Mike Blais Posted February 12, 2012 Share Posted February 12, 2012 I drove a few Macks in the 80s and I always wondered about the blue button. Never used it that I can remember. We had some older freight trailers and if you didn't charge the brakes before you backed under it the trailer could take off like a rocket. Especially on ice. Quote Link to comment https://www.bigmacktrucks.com/topic/23061-tractor-park-valve-the-blue-one/#findComment-102006 Share on other sites More sharing options...
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