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3 knobs on the dash?
When I was in school they had this ancient cabover with 3 knobs on the dash. The third was blue and the lettering was worn off. What was the 3rd knob for?
Here is a screenshot from a movie (Armed and Dangerous) so you know what I am talking about. http://i7.photobucket.com/albums/y257/Fryloc/3knobs.jpg |
I drove an old 81 r model tractor with the same thing i dont know what the blue on was for :?:
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maybe it was an ejection seat.
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I think it is an idiot light, just throw some electrical tape over it and forget it. :lol:
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This has been covered here before, but here is the info:
http://i80.photobucket.com/albums/j1...3/scan0001.jpg |
The yellow one controls brakes on all axles, the red is only for trailer, and the blue is only for the truck unit. It actually helps to have that blue one, because in winter time you'd want to have the trailer brakes released so that the residue water doesnt freeze in the air lines.
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in the winter just set the tractor brakes and release the trailer brakes to keep the trailer brakes shoes from freezing to the drums when you park
having air in the trailer lines will do nothing to stop THEM from freezing, i've had the trailer lines freeze going down the road. |
On the subject of brakes ... does anyone know what the trailer brake handle, inside the cab, is for? I only used it to check the trailer brakes before I get going, but I dont use it while driving, because it might lock the trailer axles and cause a skid.
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Originally Posted by line_transporter
On the subject of brakes ... does anyone know what the trailer brake handle, inside the cab, is for? I only used it to check the trailer brakes before I get going, but I dont use it while driving, because it might lock the trailer axles and cause a skid.
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Originally Posted by line_transporter
The yellow one controls brakes on all axles, the red is only for trailer, and the blue is only for the truck unit. It actually helps to have that blue one, because in winter time you'd want to have the trailer brakes released so that the residue water doesnt freeze in the air lines.
How long you been driving, Bud??? The yellow one only sets the tractor brakes. A really good idea in winter so that you leave the trailer brakes released and don't have to use a hammer on the shoes to release the trailer brakes before you can move. I've seen guys pull into a fuel island, when the weather conditions are right, and after they fueled up, they had to have a service truck come and warm up the trailer brake drums so they could leave the fuel island. It can save you money and grief to pop the yellow one only, and leave the red one in so the brakes don't freeze to the drums. Now, I don't know about the newer tractors, but on some of the older ones, when you set the tractor brakes, you only set them on one axle. If you wanted to have both axles holding you, you also had to lock the differentials. The new ones may be different, but some of the old ones only had one set of "SPRING BRAKES" on one drive axle. If they froze to the drums, it was a lot easier to get them to breake loose than the trailer. Another good winter tip... Get a bottle of "AIR-LINE ANTI-FREEZE" and put a shot glass of it into the red glad-hand anytime the weather gets below freezing. It tends to keep the air moving in the trailer where you need it. Otherwise, you can find that the trailer brakes will not release because of ice blocking an air line. Now the BLUE BUTTON on some of the "ANCIENT" trucks had to do with an earlier form of ABS from back in the late '70s (If I remember right). The ones that when the state trooper would aim his radar at you, the brakes either didn't work at all, or they would lock up and if you were lucky, you had enough time to get it onto the shoulder before you stopped moving. They were a ROAD HAZARD!!!!! |
It just dawned on me...
Some of the older trucks that were constantly used to haul HAZMAT also had a PANIC BUTTON that worked with the QUAALCOM in case of a hijacking. Push it and in a few minutes, you were supposed to have all kinds of help coming. |
Originally Posted by Windwalker
Originally Posted by line_transporter
The yellow one controls brakes on all axles, the red is only for trailer, and the blue is only for the truck unit. It actually helps to have that blue one, because in winter time you'd want to have the trailer brakes released so that the residue water doesnt freeze in the air lines.
How long you been driving, Bud??? go up and read the sticker, it clearly says the yellow button sets the tractor spring brakes and the trailer emergency brakes.. The yellow one only sets the tractor brakes. A really good idea in winter so that you leave the trailer brakes released and don't have to use a hammer on the shoes to release the trailer brakes before you can move. I've seen guys pull into a fuel island, when the weather conditions are right, and after they fueled up, they had to have a service truck come and warm up the trailer brake drums so they could leave the fuel island. It can save you money and grief to pop the yellow one only, and leave the red one in so the brakes don't freeze to the drums. Now, I don't know about the newer tractors, but on some of the older ones, when you set the tractor brakes, you only set them on one axle. If you wanted to have both axles holding you, you also had to lock the differentials. The new ones may be different, but some of the old ones only had one set of "SPRING BRAKES" on one drive axle. If they froze to the drums, it was a lot easier to get them to breake loose than the trailer. Another good winter tip... Get a bottle of "AIR-LINE ANTI-FREEZE" and put a shot glass of it into the red glad-hand anytime the weather gets below freezing. It tends to keep the air moving in the trailer where you need it. Otherwise, you can find that the trailer brakes will not release because of ice blocking an air line. Now the BLUE BUTTON on some of the "ANCIENT" trucks had to do with an earlier form of ABS from back in the late '70s (If I remember right). The ones that when the state trooper would aim his radar at you, the brakes either didn't work at all, or they would lock up and if you were lucky, you had enough time to get it onto the shoulder before you stopped moving. They were a ROAD HAZARD!!!!! |
Nothing to do with ABS and predates it by quite a long time. The blue button was created when the maxis were invented and before they started placing them on trailers. The blue button wont release the brakes back there. This was also on buses for a long time (maybe still is?) If you lost air out of the primary tanks in a place that was less that safe, you could push and hold the blue button and it would release the spring brakes until you release the button and or you ran that system out of air. These things are so rare (mainly because they wont really work unless bobtailing) that the only places your really going to come across them is in CDL manuals to confuse people! LOL!!!
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Originally Posted by Fozzy
Nothing to do with ABS and predates it by quite a long time. The blue button was created when the maxis were invented and before they started placing them on trailers. The blue button wont release the brakes back there. This was also on buses for a long time (maybe still is?) If you lost air out of the primary tanks in a place that was less that safe, you could push and hold the blue button and it would release the spring brakes until you release the button and or you ran that system out of air. These things are so rare (mainly because they wont really work unless bobtailing) that the only places your really going to come across them is in CDL manuals to OR TRUCKER MESSAGE BOARDS confuse people! LOL!!!
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I guess that scan of the Mack manual shown in the earlier post (which explains it all quite clearly) must be B.S. too then.
My bad. :roll: |
Originally Posted by Rev.Vassago
Originally Posted by line_transporter
On the subject of brakes ... does anyone know what the trailer brake handle, inside the cab, is for? I only used it to check the trailer brakes before I get going, but I dont use it while driving, because it might lock the trailer axles and cause a skid.
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Originally Posted by Mackman
Originally Posted by Rev.Vassago
Originally Posted by line_transporter
On the subject of brakes ... does anyone know what the trailer brake handle, inside the cab, is for? I only used it to check the trailer brakes before I get going, but I dont use it while driving, because it might lock the trailer axles and cause a skid.
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Originally Posted by Fozzy
Originally Posted by Mackman
Originally Posted by Rev.Vassago
Originally Posted by line_transporter
On the subject of brakes ... does anyone know what the trailer brake handle, inside the cab, is for? I only used it to check the trailer brakes before I get going, but I dont use it while driving, because it might lock the trailer axles and cause a skid.
I use it when sliding tandems. Unless I have an "air-release" on the pins for the trailer tandems, I will pull the handle, then get the truck moving slow and pull the Johnny-bar. It's a LOT easier on the clutch and drive train. |
Simple, the "idle away" factor for the electronic engines means that you do not have to apply fuel to get the truck moving, you simply release the clutch until the engine starts to "load" remove your foot from the brake as you come of the clutch and you are away without rolling back or having to stress the heck out of anything. This was impossible for the old trucks, even on a level grade, you had to apply fuel to keep it from stalling. It is a tough habit to break. The hand valve is nice to have to slide tandems and such, but again the possibility for abuse means that those who CAN use them correctly are not able because there are too many doomuses out there.
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...you can use that trailer brake handle to straighten yourself out if you start sliding out of control sideways on ice down a hill, give it a slight tug and put a little power to your drives, it will straighten you out, still in a fix but straighter...
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Originally Posted by Windwalker
Originally Posted by line_transporter
The yellow one controls brakes on all axles, the red is only for trailer, and the blue is only for the truck unit. It actually helps to have that blue one, because in winter time you'd want to have the trailer brakes released so that the residue water doesnt freeze in the air lines.
How long you been driving, Bud??? The yellow one only sets the tractor brakes. |
FOZZY, the WHITE-FREIGHTLINER I drove back in the late '70s didn't have to have any throttle applied with starting out. I'm really not doing anything different now than I was before the electronic engines. And, I really don't believe that that old 8V71 Detroit had anything electronic on it. Granted, I wasn't driving in San Francisco, but places like Idaho meant starting up hills too. No turbo and no jake did mean a lot of different things, though.
Originally Posted by tthunderdan
...you can use that trailer brake handle to straighten yourself out if you start sliding out of control sideways on ice down a hill, give it a slight tug and put a little power to your drives, it will straighten you out, still in a fix but straighter...
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here's a quiz
My tractor has a red button for the trailer brake, a yellow button for the tractor brake and another red button on the dash for something else, it's the same size and color as the trailer brake button, it's in the middle of the dash, can anyone guess what it's for? winner gets........ absolutley nothing
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Originally Posted by tthunderdan
...you can use that trailer brake handle to straighten yourself out if you start sliding out of control sideways on ice down a hill, give it a slight tug and put a little power to your drives, it will straighten you out, still in a fix but straighter...
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Originally Posted by Fozzy
Originally Posted by tthunderdan
...you can use that trailer brake handle to straighten yourself out if you start sliding out of control sideways on ice down a hill, give it a slight tug and put a little power to your drives, it will straighten you out, still in a fix but straighter...
There are times when you DO use the trailer brake, but going down a slippery hill is NOT one of them. |
Fredog said:
go up and read the sticker, it clearly says the yellow button sets the tractor spring brakes and the trailer emergency brakes.. If you hold the red knob in, while pulling the yellow, you are setting ONLY the tractor brakes. The manual ALSO says, that if the air pressure drops to the critical level, the yellow knob activates, and again..... just as I stated above, the red will pop out TOO! The wording is confusing, because it assumes activation of the yellow knob by itself with no Driver Control over the red knob. Very simply.... yellow=tractor, red=trailer. The blue knob was for a MANUAL (not air pressure balanced) application of the tractor brakes to be used temporarily while starting the OLDER trucks. |
Originally Posted by Windwalker
Originally Posted by tthunderdan
...you can use that trailer brake handle to straighten yourself out if you start sliding out of control sideways on ice down a hill, give it a slight tug and put a little power to your drives, it will straighten you out, still in a fix but straighter...
I don't want to rehash that whole argument that I had with Rocky over this, but I still believe.... and have experienced..... the "drag chute" affect of applying a LITTLE braking power, using the trolley valve, to the tandems to help straighten things out, EXACTLY as ThunderDan is saying. And it works whether it is your drives or your tandems that are sliding. But, it is not an EASY maneuver, and many CAN mess up by doing it. However, I also agree with you that, past a certain point, it will not work. |
...I did it Friday...empty flatbed...it ain't got antilock...and yes if you do get to that point you have already screwed up to be bending in the middle down a slippery slope...
I think having a trailer without antilock and a tractor with antilock can be tricky...the first couple of quick stops empty on a slick surface anyhow... |
...how about jake brakes on slick roads?...some say you should never use them...thoughts?...
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Originally Posted by tthunderdan
...how about jake brakes on slick roads?...some say you should never use them...thoughts?...
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Think about the physics of it.
Using the jake puts a drag only on the drives. The rest of the weight is still pushing you forward. Once the drives break traction, how much weight and inertia do you have trying to maintain the same speed or speed you up? Theoretically, (if your brakes are properly set up) by using the brakes, you are distributing the drag throughout the vehicle. Some years back, I was on I-70 in CO. On the east-bound side, when I came out of the tunnel, there was a truck that had jack-knifed going down the hill. We all came to a stop and when I set the brakes, I only set the brakes on the tractor in case the trailer brakes might freeze up. I quickly discovered that the tractor was starting to slide forward. The only way I could stand still was to set the trailer brakes as well. Now, that is: FROM A STANDING STOP, SET THE TRACTOR BRAKE AND RELEASE THE PEDDLE, AND START TO SLIDE FORWARD. Now, translate that into the jake. If you can get into serious trouble by applying too much power to the drives, you can also get into very serious trouble by applying too much brake to the drives. |
Originally Posted by golfhobo
Fredog said:
go up and read the sticker, it clearly says the yellow button sets the tractor spring brakes and the trailer emergency brakes.. If you hold the red knob in, while pulling the yellow, you are setting ONLY the tractor brakes. The manual ALSO says, that if the air pressure drops to the critical level, the yellow knob activates, and again..... just as I stated above, the red will pop out TOO! The wording is confusing, because it assumes activation of the yellow knob by itself with no Driver Control over the red knob. Very simply.... yellow=tractor, red=trailer. The blue knob was for a MANUAL (not air pressure balanced) application of the tractor brakes to be used temporarily while starting the OLDER trucks. |
Originally Posted by Mack2
Originally Posted by golfhobo
Fredog said:
go up and read the sticker, it clearly says the yellow button sets the tractor spring brakes and the trailer emergency brakes.. If you hold the red knob in, while pulling the yellow, you are setting ONLY the tractor brakes. The manual ALSO says, that if the air pressure drops to the critical level, the yellow knob activates, and again..... just as I stated above, the red will pop out TOO! The wording is confusing, because it assumes activation of the yellow knob by itself with no Driver Control over the red knob. Very simply.... yellow=tractor, red=trailer. The blue knob was for a MANUAL (not air pressure balanced) application of the tractor brakes to be used temporarily while starting the OLDER trucks. [FIRST post from the Hobo while on the road!! This is KEWL!] |
[quote="golfhobo"]
Originally Posted by Mack2
Originally Posted by golfhobo
Fredog said:
go up and read the sticker, it clearly says the yellow button sets the tractor spring brakes and the trailer emergency brakes.. If you hold the red knob in, while pulling the yellow, you are setting ONLY the tractor brakes. The manual ALSO says, that if the air pressure drops to the critical level, the yellow knob activates, and again..... just as I stated above, the red will pop out TOO! The wording is confusing, because it assumes activation of the yellow knob by itself with no Driver Control over the red knob. Very simply.... yellow=tractor, red=trailer. The blue knob was for a MANUAL (not air pressure balanced) application of the tractor brakes to be used temporarily while starting the OLDER trucks. [FIRST post from the Hobo while on the road!! This is KEWL!][/quote] It was bad enough we ( moderators ) had to worry when you were home, now it's going to be 24/7 :shock: I'm going to have to have more money! :lol: |
Not to worry, Ridge! I haven't bought a laptop yet, and of course, I can't get on from ANY truckstop in the country... since they've ALL been banned... but I'm at a motel this weekend due to circumstances beyond my control, and using the "access puter" in the lobby! Of course... i do stay here from time to time! :lol: :lol:
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Whew!!! I thought maybe you had up-graded to the 21st century. :lol:
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Originally Posted by Ridge Runner
Whew!!! I thought maybe you had up-graded to the 21st century. :lol:
Of COURSE I'm gonna join the new century!! But, by then it may be the 22nd! :wink: |
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