How to bobtail a dolly?

on the basis of "the only dumb question is one you should have asked and did not" --> I passed the driving portion a few days ago with only 2-3 hours drive / instruction [ score 92 - took off for yield signs with no traffic in 1000 yards ] but did not get a chance to refresh on air-hose and am starting to talk to recruiters so like the cab had two knobs -{ red + yellow }- which operated as I expected = yellow is trailer so the other one has to stop the pressure-feed to the brake-operation on the trailer, there was a lever which I was told operates the trailer brakes only -{ as expected, never really use it much }- but it has been forever and I did not get many miles in decent equipment .... what is "..... the service valve, "blue", closed" as I only remember one of the hoses being color-coded blue and with the num-rods we are getting today I will remember it wont work right if the hoses are backwards, I think you are supposed to cross them but who knows in today's world ....

anyway - what blue knob?...

if they call the red-knob "tractor protection valve" I better ask someone who actually knows & do most equipment have that slack-adujster

per taildragon's statement?.... I have never seen a triples close enough to see, I can go to Cefco or Lucky's truckstops and look if it will help ~ I do not want to end up like --> Brandonpdx <-- as I dont mind looking stupid but others cannot take it like I can and get to be a safety-risk of their own thinking for me = like thinking a red plastic knob on a valve-stem is going to protect something

 

okay nicholas_jordan here goes... The yellow button on the dash of the truck is the tractor parking brake and the red button on the dash is what we used to refer to as the tractor protector valve, should be better known as the trailer emergency air supply. The red button nowadays gets its air supply from the valve that is the yellow button on the dash, "tractor parking brake", so when you pull the yellow button you are actually setting the spring actuated brakes on the tractor and trailer, "meaning, no air is required to hold the brakes on, ie: locked up the brakes". If you are going to drop your trailer for example, you would pull the red button, "which will stop supplying air to the trailer through the red hose, and therby set the brakes as mention above". Then you would back the tractor up against the kingpin, "to make the fifthwheel lever release handle easier to pull out", then you would pull the yellow button out to set the tractor parking brakes, then go about dropping your trailer. Whenever the red button is pushed in, there should always be air coming out of the "red" gladhand that hooks to the trailer, this is refered to as "the emergency line", it is ALWAYS red. When you are hooked to a trailer with the red button pushed in, this charges the trailer air system, and when the trailer air system is charged, when you step on the brake pedal or pull down on the handvalve, "the lever on the dash or steering column" this puts air pressure on the "blue" gladhand, "refered to as the service line", that hooks to the trailer, which actuates the trailer brakes. Now, whether doubles or triples, whether it is the front or rear of a trailer, the emergency line is always marked "red" and the service line is always "blue", and the valves refered to in the earlier post were the valves that you would find at the rear of the trailer, "they are red and blue", right where you would hook up your convertor dolly. The normal trailer does not have these valves at the rear, only trailers that are set up to pull doubles and triples would have them. I hope this covered everything, if not feel free to chime right in.

 

so the red button brings up the pressure in the air-liine / reserve-tank on the trailer ~ operation of the pedal { brake } at that point releases some of the air on the airline that is marked red at the glad-hand at the front of the trailer - which has nothing to do with "blue-button" which will be at the back of a pup-trailer set up for multi-trailer operation -{ starting to miss something here }- "button" on a trailer?... I guess I better go to a lot and do some walk-around ..... would seem they would have a ball-valve near the dolly hook-up for the trailer-supply line, hence would be blue & thus the original statement I did not grasp .... I'm gonna expose my "stupidity" here as OP may not be able to take it and I can so for the benefit of all: -{ the yellow valve does not set the trailer parking brakes except that the colorado ( spanish for red ) knob is supplied by the Yellow Knob therefore when the YELLOW knob is "pulled" there is no supply to the red knob, the Yellow knob actually activates "parking" on the tractor and not the trailer like I thought }- ( no major risk all these years as my operation would have been to bring the entire thing to complete stop and pull both knobs and go get somebody who knows WTF is going on ) ......

wow, I am glad I asked !!!......

pulling the yellow knob would have to discharge the red knob for that to work,.....and the red-knob in the "to the dash" position - if pulled - would place the shoes on the trailer against drum/disc using the springs or whatever they use today to hold the parking brake on on the trailer, the pup-tank on a trailer could only hold local-reserve to shed a hundred milliseconds bringing the pads against the friction surface of the drum/disc

so to hook up the second trailer on a standard double with no "college-edjeurkated" busts, one would upon getting a ticket from the dispatcher hook up front trailer in normal fashion, blue valve at back of trailer is closed - red knob is in on the dashboard - take the tension off the latch on 5-th wheel & release the latch to the latched position / minor walk-around to see that no one has approached the near-area while doing this ...... release red knob ( push-in ) & tug-test + approach second-trailer bcs some kind, contentious trucking school graduate has left the dolly ..... nope,.....

back to a dolly, get the ring in the pintle-hook using bravado & strength & latch ..... there has to be a blue-line on the "dolly" ( converter?....) so that has to "charge the dolly" and there has to be "blue-line" as well as "trailer emergency brakes" and both of those lines have to service both the (gizmo that will become the front-axle for the trailer) so if there is a blank "glad-hand" on the "converter-dolly" that presents an extreme risk that it would blow-off while "rigging-up" all this / but however that is done we then back to the second-trailer and attach ....

this is going to be fun the first twenty times ..... I hope yard-boss(es) realize how involved this is......

 

Okay, lets try this, lets say that there is no trailer hooked to your tractor. Now lay both hoses out on the deck plate and have a friend push the red button in on the dash, now you will hear air coming out of the hose with the red gladhand, but nothing coming out of the hose with the blue gladhand. Okay, with the red button still pushed in and air coming out of the red gladhand, have your friend step on the brake pedal and air will start coming out of the blue gladhand, at this time you will have air coming out of both hoses.

 

As for the red and yellow buttons, you can push the red button in and charge the trailer even though the yellow button is pulled out. It will however pull the red button out, "for your convenience", when you pull the yellow button out, say if you were just coming in off the road.

 

okay, I thought I was missing something but bet I am not ( copious edits to the previous post add additional material )

You ^^CANNOT^^ have the Yellow button pull the red button for you if you pull the yellow button then have pushing the red button in hold unless some really tricked-up controls are now used ...... I never really got to this level of detail but if operation of the yellow knob, pulling it at parking, shuts the air to the red line and that operates "trailer parking brakes" then .....

obviously if I had a truck in front of me this would be simpler but after the way Jeff got distracted by what I was saying I have to work this with somebody with greater time driving for ($) ....

somethin is screwy here and it aint me......

pull yellow it helps the fellow but Colorado can stay in on it's own.... except if the Yellow knob decides to assist

not trying to be funny, I can take it and maybe OP cannot

 

I would go and get in a truck and operate the valves and see how they work so that you will understand. To make it easy to figure out look at it this way, the yellow button is the tractor parking brake and the red button is the trailer parking brake, the rest will come to you in time.

 

The convertors will have dummy gladhands mounted on the framework somewhere just for this purpose, just hook the hoses to them and they are sealed off. Same goes for the power cable plug, they will usually have a female receptacle to plug in to for powering the tail lights and brake lights/ turnsignals. It is pretty common to have to move a convertor and lead trailer to a different location to pick up the trailing trailer. Each company specs their equipment differently, so there will be variations.