question about semi- horn

movingguy · #1 (**permalink**) 12-15-2008, 01:33 PM

I'm new to this forum, so I hope this hasn't already been asked (I didn't find it anywhere).

Does the horn on a semi- work when the engine is off and the truck is parked? Also, are they generally activated from a button on the dash, or from a pull cord or lever higher up? And, lastly, do semis only have the super loud air horns, or do they have other, lower impact horns (more like a car horn)?

Thanks!

wayne100 · #2 (**permalink**) 12-15-2008, 02:27 PM

Yeah they work when the truck is off, it's air powered so as long as you have air pressure they will work by pulling on the rope. And yes they also have a regular car horn also right on the steering wheel, but you can barely hear it.

vwaggs · #3 (**permalink**) 12-15-2008, 02:30 PM

Welcome to the New Age!!! The answer is all the above. Semis are equipped with 2 horns. The regular and the city. The city horn sounds much like the one in your car. Its there so the drivers of 4 wheelers don't "freak out" when its sounded. It should work when the vehicle is off. The other horn is the air horn. Its decibel rating may vary. Volvo for example, has taken to installing a rather low decibel one. Low enough that if someones kid is pulling their arm up and down as they go by, you avoid looking at them because its embarrassing to listen to. It operates off the steering wheel, though only if adequate air pressure is present. Many other trucks still have the over your head, ear splitting air horns that operate from an overhead valve. It also requires air pressure to be present to properly operate. Hope I helped.

movingguy · #4 (**permalink**) 12-15-2008, 03:08 PM

Thanks! Those answers are very helpful!