Hand Valve Brake

lol. anyone that says they were looking in their mirrors at how fast the trailer tires are turning,and "gently" appying the johnny bar to stop a jack knife have never been in a jack knife.

if you got all this time you weren't breaking traction, you were just screwing around with the johnny bar.

 

I have been thru a formal commercial skid pan training school.
It was a long time ago and it was with an R model Mack and a flat bed with a jackknife cable control system on it.
They would wet the skid pan down and make drive at about 40 mph and then they put you in a jack knife situation.
They taught us two strategies to pull out of it.
One was to mash the throttle as hard as you could and the other was the trolley brake.
When I have gotten in to these situations over the years my go to strategy is mostly mash the gas.
The problem is there is a point of no return for either strategy so when your on slippery roads you better be on your game and watching that mirror.

 

Each of those two solutions require traction. There is no way to fool physics.

 

i have yet to see a jackknife where the trailer came around. it is always the drives that broke traction,and the trailer pushed the drives around past the steer axle. thats why you see these guys wadded up in the ditch with the trailer pointing in the direction of travel and the truck pointing back.

mashing the throttle just hastens the end result.

 

exactly. the trailer is coming around the truck yet the truck has traction.

lol!

yep. and a turbo3000 will get you a 10% mpg increase......

 

Well if you never use your clutch to slide tandems, how do you unstuck the pins?

Dunno what kind hills ur on, or freight, or truck, or spacecraft, but I know the only purpose for that trolley valve is to straighten your trailer when it doesn’t want to be.
And if you can see the wheels turning, you have some really good eyes.

 

This is easy to demonstrate.. get a toy tractor trailer (hot wheel's etc).. prop up a table so its a "mountain".. place some tape on the drive wheels and let it go.. almost instantly the drive axles come out and the truck jackknifes.. now tape the tandems and to the same.. this time, the trailer will come around almost instantly. The trailer hand valve is for checking the brakes and other things done when NOT MOVING or barely moving. The hand valve was really important before trailers had spring brakes.. You had to apply the trailer hand valve to connect to the trailers.

Also.. the foot valve works like a volume knob... the trailer hand valve is an on off switch.. I'm going to "unwatch" this topic.. because its just full of foolish people demonstrating nothing but their love of "trucker myths"...

 

A jackknife is AS you just described it. However there are times when a trailer can swing around and not jackknife. I have seen rigs switch ends in rain and ice. I don't subscribe to the theory there is only one correct use of the hand brake though.

 

i got an air slide and my pins don't stick. trying to twist the truck in half doesn't unstick pins anyhoo.

i agree on seeing the wheels spin. but i guess when the truck is sideways just look out the side glass.

 

about the only time you see a truck with the cab pointing in the direction of travel and the trailer at 90 degrees or any angle in between is in a situation like these pile ups in the winter where they come up on stopped traffic too fast and have to stand on the brakes all the way to loss of control or crash. so go ahead and play with the johhny bar....what good is "gently" applying the trolley valve gonna do there.