Trolley Brake???

Back in the day Schneider used to train on a skid pad. Now they use a simulator which isn't as good as real jk

 

[QUOTE="semi" retired;4177787]Hi davenjeip, I've heard 17 degrees is the point of no return for a jackknife, which isn't much.[/QUOTE]

The "point of no return" is when the trailer hits the back of the cab. The basic laws of physics are in play, where an object in motion tends to stay in motion unless acted upon by an equal or greater force. When you apply the brakes, weight transfers to the front. As this happens, the rear may lose its ability to slow as quickly as the front is attempting to get the vehicle whoa'd up. In a single vehicle, you'd call it a fishtail, but in a combination it is usually the trailer stepping out. In some cases, it might be the drives locking up and sliding off to the side while the trailer continues to push forward. In any case, your first move would be to stop trying to slow the tractor (get your foot off the brake) and apply light throttle...remember to keep steering the truck where you want it to go. As long as the steer tires are rolling, the rest of the truck will follow wherever they are pointed. Slight application of the trailer brakes will also help straighten you out since they are going to tug at the rear of the tractor to keep the drives from passing the steers. A trailer with the brakes applied will never pass an accelerating tractor...it may not be pretty, but as long as you've got open space it'll come back to you no matter how slideways it got.

 

Been a trucker for so many years I can only recall using it a cpl times mainly to check trailer brakes and lights, as well as on some inclines. One winter in Bloomington IL during a blizzard my trailer (empty van) decided to get blown into the median....yanked the Johnny bar and pulled the trailer back in behind me.....Found an exit after that ##### lol Other than these few exceptions I use mine to hold my Bluetooth earbud!!

 

If you use the trolley, and the trailer loses all traction... you would need to slowly speed up to stay in front of the trailer. If you are braking with the trolley, you are not likely to remember to speed up. The axle that has lost traction will want to lead! Go through this and decide which is the preferred axle to lead. If trailer loses traction, what happens? If drives lose traction, what happens? If steers lose traction, what happens? It is always best to utilize your pedals, and slowly adjust your speed than to use your trolley. Posters are right about the delay being difficult to factor in when in an emergency situation! I am impressed that other drivers are thinking about and preparing for emergencies ahead of time! It shows dedication and thoughts toward safe driving!

 

I USED TO use the trolley brake during slick conditions. Light application of braking only to the trailer tires will help correct a trailer getting out of line and can also be helpful if the tractor begins to yaw.

Note my emphasis on "used to".

The problem is that after driving three different trucks up to a '03 KW T2000, all the trucks I've driven since are "modern" (ie. 2011 or newer) trucks whose trolley brakes...

... uh, what's the technical term?...

... SUCK!

By this I mean that even the lightest application of the trolley brake would immediately apply 20-25 lbs of brake pressure. That's INSANE! For the folks that are talking about how trolley brakes will lock up the trailer tires and that's why you don't use it, well that's the answer. Every modern company truck I've been in since last year have trolley brakes that are improperly calibrated. I've driven seven such trucks in the last 15 months, and every one of them had the same problem...

... except for the new '15 KW T680. The company finally figured out how to solve the trolley brake problem altogether...

... there is not trolley brake. They spec'ed it without it.

On the older trucks, especially the '03 KW, the trolley brake could be gently applied with 2-5 lbs of pressure. I can tell you from experience that came in real handy during a blizzard on I-40 in New Mexico and Arizona last year. The trolley brake was on the steering column, so you didn't have to "break connection" with the steering wheel and lean over to engage it.

The moral of the story is this: if your truck has trolley brakes, then test it to see whether you can lightly apply up to 5 lbs of pressure. If you can't, if it suddenly jumps up to 20+ lbs of pressure, then forget about using it on the road in slick conditions. No wonder the company got rid of them.

 

I use it during my pre-trip. You can find small air leaks and bad brake lights. You can also roll a bit and check you trailer brakes. It helps to isolate the problems. I also used them when I was pulling triples. With LTL freight they get highly upset when their load is not there in the morning. So running north Nevada in the winter that trolly helped getting down the grades. If you're not experienced please do not try this. If there's a slight coating of ice on the road you can go down small grades and keep the set straight. I would apply about 3 to 5 psi brake pressure and the set would be just fine. You don't want the brakes stopping your trailer just enough application to hold back. Of course we all know if it's real bad you'd drop the last box and go on. But I'll tell you it's hard to keep on the good side of the morning crew when the truck that ran the same route came in with no problems. If it's real bad you pull over but when the ice and snow are light you know the truck and your abilities so you don't run and hide.

 

GasHauler, I'm curious what truck you drove with those triples? Personally I'd love to have a truck with a decent trolley brake where I can apply light brake pressure.

 

I was a company driver for a cheap company out of Las Vegas NV. We had simple single screw tractors that pulled 3 20' pup trailers. IIRC the truck make was Freightliner and had nothing in it. For power they ran Cummings 350 but that was ok since we really didn't carry any weight. The main problem was dropping and hooking a trailer out in the desert at night. We had one stop that was to a mine. You dropped the trailer next to the others in the dirt. Most of the time the mine was my first stop so you knew that the trailer was going to have some kind of weight. Just about all the time it was the middle box. But after awhile I could break down the set, get the middle box and park it at the mine then rebuild the set all in about 15 minutes. Back in 1991 the pay was 27½ cents per mile. They had little miles with a lot of work.