quote:
Originally posted by JonS:
How come Police cars, taxis, Delivery trucks, Ambulances ect last so long if they are idling most of the time? It must not be too bad for them.
I'm not sure about taxi fleets, but Emergency fleets are usually equipped with Fast Idle boxes from Kussmaul or others.
Not too often you see an ambulance or fire truck switched off at the scene. Sometimes they run for 1-6 hours.
To shut if off with the strobes flashing would leave the battery dead in about 5 minutes. For rescue equipment, the PTO must power the hydraulics, air system, and pumps.
Also don't forget for most emergency and rescue equipment, you can expect the crew to race from scene to scene, so a motor wouldn't last long if shut off, cooled off, then restarted and immediately at WOT.
Or would you want your EMT driver to "gently" drive to your massive coronary to help prolong the life of the ambulance motor?
So with most emergency equipment, the driver pokes the "FAST IDLE" button at the scene and the motor immediately jumps to 1,300-1,500 RPM and stays there.
The newer equipment is fully automatic, no button to push. It monitors the batteries and load demands, once the voltage drops the fast idle kicks in.
On either Kussmaul system there is a safety override so when you step on the brake pedal, it drops back to low idle so you don't shift your expensive Allison automatic transmission into Drive at 1,500 RPM. That could be spectacular.
Most new electronic fuel injection HD diesel motors are factory equipped to provide fast idle through the SAE J1939 data interface bus. The Cummins equipment I operate is so equipped, just have to plug in the appropriate black box.
This is perhaps why a few folks I know got used surplus Chevy Caprice '94-'96 police cars at auction. They were cheap, easy to rebuild, and they added the Kussmaul box. So in temps colder than -30 C, they hit the button and the LT1 motor runs at 1,500 RPM.
Jerry