testing trailer emergency brakes versus testing trailer service brakes

Yes it is. What model Kenworth did you drive

 

Shouldn't it be a requirement to have a method to check if your trailer service brakes are working? How else can you do it without a trailer brake handle or switch? Seems to be extremely unsafe.

 

Dude most megas don’t spec their trucks with hand brakes.

 

You don’t know it but that’s sad. Not about you, but about the piss poor company’s running trucks today.

trailer hand valves used to be standard equipment, I personally couldn’t do my job with out one.

 

So by pulling the red knob you are cutting off the supply of air to your trailer which in turn engages parking/emergency brakes. Wheels equipped with parking brake chambers must be supplied with air via red line to disengage spring. To test service brakes(blue line) on only trailer you would have to have a trailer only hand valve. Foot valve sends air to tractor and trailer together(same time). The red knob is pushed in to supply trailer with its air supply(tanks suspension so on) which also disengages parking/emergency brakes. The emergency brakes are controlled by spring which uses air pressure to release. Service brake and emergency brake are not controlled the same way although both are controlled by air pressure just from different sources on the tractor. Not all trailers have emergency brake chambers(old ones). I hope this makes sense. Maybe a good you tube video would be better if you can find one.

 

TJB15 did a fine job of explaining the function,,s of the air brake system.As far as hand brake/trolley valve/Hand spike and many more names it's been given over the yrs,it's rare to see one in theses larger company's trucks as they have more uses besides testing your service brakes on the trailer,they can get you out of a jack knife situation,IF you know what your doing and in the same breath,they can cause a jack knife if you DONT know what your doing. It's all how the truck is ordered and built and apparently many think they would cause more issues then it would be worth! I worked as a diesel tech starting in the eighties and every truck they owned and ordered had a hand spike,but then again they only hired the well experienced. After 10-15 yrs of my 21 yr run with the company,none of the trucks came through with them,but they also started hiring students about the same time! Was it because of that or was it to save money? Because they also started coming through with fixed 5th wheels instead of sliders about the same time! Hope this helps,if only a little.