r600 Posted October 20, 2007 Share Posted October 20, 2007 can anyone tell me what this is?inside the cab l/h side with side circuit breakers, is it low air buzzer???????thanks adrian Quote Link to comment https://www.bigmacktrucks.com/topic/2990-can-anyone-tell-what-this-is/ Share on other sites More sharing options...
fjh Posted October 21, 2007 Share Posted October 21, 2007 can anyone tell me what this is?inside the cab l/h side with side circuit breakers, is it low air buzzer???????thanks adrian is it low air buzzer??????? I beleive you are correct Quote Link to comment https://www.bigmacktrucks.com/topic/2990-can-anyone-tell-what-this-is/#findComment-14597 Share on other sites More sharing options...
lamountain1976 Posted January 28, 2008 Share Posted January 28, 2008 is it low air buzzer??????? I beleive you are correctWhat about this? Quote Justin LaMountain Consulting Forester and Horselogger Green Man Forestry Link to comment https://www.bigmacktrucks.com/topic/2990-can-anyone-tell-what-this-is/#findComment-16567 Share on other sites More sharing options...
blueknight0517@yahoo.com Posted January 28, 2008 Share Posted January 28, 2008 Rusted plate with two rusted screws and a "thingy" on the back, also has a bare wire which blasted the fuse.(Sorry, I couldn't help myself) Quote Rustednut Link to comment https://www.bigmacktrucks.com/topic/2990-can-anyone-tell-what-this-is/#findComment-16572 Share on other sites More sharing options...
lamountain1976 Posted January 28, 2008 Share Posted January 28, 2008 Rusted plate with two rusted screws and a "thingy" on the back, also has a bare wire which blasted the fuse.(Sorry, I couldn't help myself)Bastids..Okay it has a type of spring loaded switch on it, was found over on the right hand side of the engine and one of the wires goes to the Jake Brake (I think). Quote Justin LaMountain Consulting Forester and Horselogger Green Man Forestry Link to comment https://www.bigmacktrucks.com/topic/2990-can-anyone-tell-what-this-is/#findComment-16573 Share on other sites More sharing options...
HK Trucking Posted January 28, 2008 Share Posted January 28, 2008 Jake brake switch.It would be mounted at the throttle lever on the injection pump.When the throttle returns to idle the throttle lever contacts the switch causing the Jake brake to come on (provided the dashboard switch is on and the clutch pedal is all the way up). Quote "If You Can't Shift It Smoothly, You Shouldn't Be Driving It" Link to comment https://www.bigmacktrucks.com/topic/2990-can-anyone-tell-what-this-is/#findComment-16575 Share on other sites More sharing options...
theakerstwo Posted January 28, 2008 Share Posted January 28, 2008 Jake brake switch.It would be mounted at the throttle lever on the injection pump.When the throttle returns to idle the throttle lever contacts the switch causing the Jake brake to come on (provided the dashboard switch is on and the clutch pedal is all the way up). He is right jake brake switch. glenn Quote glenn akers Link to comment https://www.bigmacktrucks.com/topic/2990-can-anyone-tell-what-this-is/#findComment-16576 Share on other sites More sharing options...
lamountain1976 Posted January 28, 2008 Share Posted January 28, 2008 Interesting. So this would have been mounted to the injection pump below the throttle lever, and (provided the dash switch is on), when I take my foot off the accelerator and the the throttle lever rotates back to idle position, it depresses the jake brake switch, which then tells restricts exhaust flow?This is one of the things that don't work on the truck and I think you can help me understand it. So then the dash switch is a three-way switch? With wires running to power, ground and the JB switch? And what is the JB switch connected to and how does the JB actually work to slow the truck? Quote Justin LaMountain Consulting Forester and Horselogger Green Man Forestry Link to comment https://www.bigmacktrucks.com/topic/2990-can-anyone-tell-what-this-is/#findComment-16577 Share on other sites More sharing options...
ThaddeusW Posted January 28, 2008 Share Posted January 28, 2008 Interesting. So this would have been mounted to the injection pump below the throttle lever, and (provided the dash switch is on), when I take my foot off the accelerator and the the throttle lever rotates back to idle position, it depresses the jake brake switch, which then tells restricts exhaust flow?This is one of the things that don't work on the truck and I think you can help me understand it. So then the dash switch is a three-way switch? With wires running to power, ground and the JB switch? And what is the JB switch connected to and how does the JB actually work to slow the truck?Ok first thing is Mack made their own engine brake called the Dynatard which is different than the Jake brake. But you could pick if you wanted a Jake brake or a Dynatard. The Jake brake uses a valve cover spacer kit which is easily noticeable. They both operate on the same principal of compression release. When the engine brake is activated it cuts the fuel and alters the valve train timing by opening the exhaust valves at top dead center of the compression stroke. Compression requires power so the engine absorbs power compressing air. The wiring is simple, you have three or four switches. -The first dash mounted switch is the on/off switch.-The second dash mounted switch is sometimes not present and it is the hi/low or sometimes a hi/med/low switch. It selects either 3 or all six cylinders or 2, 4 or 6 cylinders. -There is a clutch switch so if you press the clutch it turns the brake off to prevent stalling the engine-Then the throttle switch which actives the brake when you take your foot off the accelerator. Here is a pretty good diagram from a book on Google booksLooks like a good book too. Nearly the whole book is there on Google. Quote -Thad What America needs is less bull and more Bulldog! Link to comment https://www.bigmacktrucks.com/topic/2990-can-anyone-tell-what-this-is/#findComment-16585 Share on other sites More sharing options...
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