What's the inc/dec button for?

Cruise?

 

If its a older truck its to idle up eng>

 

If you have a PTO you idle up to run it. Ran 'em in the oilfields and we always idled up after engaging the PTO.

Also, I've always been told that when you are idling, whether for sleep or just parked, you should idle up because its better for the engine. Why its better for the engine I do not know, but that is what I have always been told. I think it has to do with keeping the oil pressure up, but I'm not sure.

unloader

 

The older trucks didn't burn fuel as efficiently as the new ones. At idle the cylinder wouldn't burn all the fuel, so in long idle times like a break, you would get cylinder washdown (excess diesel builds up and works it's way down the cylinder and into the oil) thus causing your oil to be diluted. Raising the rpms at idle increased the cylinder temp and helped prevent this. Plus some of the older engines didn't produce much heat at idle, and in cold weather the increased rpm helped the engine produce enough heat. Most of the trucks I had would automatically tach up to 1000 rpm when you hit the cruise 'set' button with the brakes popped

And you can tell this is an older truck, (Freightliner?), it's been a long time since I've seen a start button.

 

On the old cummins you can also bump up or down your idle so your mirrors don't shake or truck dont rattle as bad. I believe it goes 650 to 900 rpm

 

it's attached to the radio... abbreviation for increased decibels

 

Click it and find out

 

increase/decrease