how do semi control their trailer brakes?
Posted by AggressiveTip5908@reddit | Truckers | View on Reddit | 17 comments
so i was nearly clean up today in rural australia, there were road works the workers were putting red dirt pea gravel down along a stretch of road watering and grading it, they had a temporary traffic light out that was red while they did another lap down the stretch of road so i came to a stop at the light rolled a smoke and waited a couple minutes, then all of a sudden this semi with 2 grain trailers on came flying up my ass swerved around me through the light up the bank to get around the water truck and grader and still on into the distance, anyway as he was passing i was looking at his tyres and some of them were skidding and some were rolling then it would alternate, do you lot have control over each axel or trailer or is it all computer controlled how does that work?
luddite86@reddit
Damn! Where did this happen?
AggressiveTip5908@reddit (OP)
just outside of kalannie wa
NewSaargent@reddit
What road are they doing roadworks on? Taking an oversized load through Kalannie tomorrow and no roadworks are posted by MainroadsWA. Not doubting you we're forever finding unlisted roadworks which screws up the best of plans
AggressiveTip5908@reddit (OP)
i just checked my map history i was travelling for 22 minutes but only got 7km so that must be it dowerin kalannie rd closest cross rd is bunketch E rd
NewSaargent@reddit
Well that's shit because we're definitely going to have to go through there, thanks for the heads up.
AggressiveTip5908@reddit (OP)
im fairly certain it was there the map says i was travelling for 25 min and only made it 7km.
you might want to get your pilots a couple k ahead those cunts are coming out of the granary full and arnt stopping in a hurry on the gravel
AggressiveTip5908@reddit (OP)
Dowerin-Kalannie Road: 5km of reconstruction is underway.
Ballidu East Road: Culvert replacements are taking place.
i dont know why main roads isn’t showing it i think it was dowerin-kalannie rd but i was just following gps i really couldn’t tell you
TruckeronI5@reddit
Ya, he is probably a shitty driver that is too lazy to adjust all his brake adjusters, the skidding ones might have been adjusted too tight or the others way out of spec or even failing to engauge.
GiantEnemaCrab@reddit
Shitty driver? This is just rural Australia. Haven't you seen Mad Max, they all drive this way.
AggressiveTip5908@reddit (OP)
so trailer maintenance and brake adjustments are the responsibility of the driver? i would have thought they’d be rented out each trip and serviced by a mechanic, are the adjusters like a gauge on your dash or more like stick a flat blade into the back of the drum and wind the cog in and out?
TruckeronI5@reddit
Like a car, each set of tires on each side has a brake drum and brake pads. There is a bolt on each brake attached to the axle that you turn to adjust the brake pads, to move them closer or further from the drum. Just like the adjuster on your brakes you mentioned. You use a hammer as a kind of pry bar to pull on each adjuster to see how much it moves and there is a specific range it needs to move, not to little and not too much. You test the movement with the hammer and use a wrench to adjust the brakes to the proper setting, only takes a few seconds each brake. A proper driver will check and adjust the brakes on every new trailer they hook up to before heading out on a trip also before hitting the mountains. If all the brakes are not adjusted properly and equally you will have some brakes not doing their fair share of the work and the other brakes having to work harder. It is the drivers responsibility to do this.
homucifer666@reddit
More like the latter. On drum brakes, there's an S cam with slack adjusters that you have to manually tune.
Mechanics do usually handle this, but like everything else on the vehicle, the driver is responsible to make sure it's in good working order; at least, here in NA. Can't speak for Oz.
FilthyNasty626@reddit
Can't speak for my Aussie friends, but in the US we can adjust our slack adjusters. Personally, I like right trailer brakes. I adjust the brakes until there is no ring if I thump the drum with a wrench, back off until it starts to ring out, then back off 1/4 of a turn. That well within DOT tolerance. Most brakes are looser than that over here. Now, on the road, I am looking ahead as far as the eye can see and I am on my jake (engine brake) long before I need to use my service brakes. That's what that driver in your experience should gave been doing. My last company truck gad 174k miles on it when I retired and still had >90% brakes left from the factory. My personally owner truck has 934k on it. It has had one brake job in its life around 500k. It still has 75% brakes left. Why? I use my engine brake and I pay attention.
AggressiveTip5908@reddit (OP)
can you control the jake brakes by riding the clutch or will you stall? do they have any sort or governor or are they just on or off? are they a good idea for gravel?
FilthyNasty626@reddit
Yes. Just press them gently, as long as you hit the clutch sensor you can switch them off without engaging the clutch. They do have a governor, my truck has stage 1 - 3, so 2 cylinders braking, 4 or all 6. I don't recommend using them on gravel for new drivers. Especially when empty. Loaded and experienced drivers, use em! Jakes basically take the energy back through the drivetrain, compresses air in the engine and shoots it out of the stack. It's a different animal than uses the service brakes. A lot more forgiving if you aren't on a slippery surface like snow or ice. In the instances, I won't use it if empty, but will depending on how much weight I have. Gravel and sand is a lot grippier than ice and packed snow.
CashWideCock@reddit
Each wheel cannot be controlled independently. What you described is how the ABS system works when doing a hard stop.
IIxNullxII@reddit
First off, that driver was a mad man. Second, we can't usually control brakes independently like that. I garner that he was on the brakes hard enough that the ABS system was trying to prevent lockups by doing what you saw. Now, many tractors are equipped with a trailer brake leaver that will let us engage the brakes on the trailer only, in case we want to test just those brakes or try and prevent some slippy slides on ice. Other than that, likely ABS.