Why does an ambulance sound like its engine revs to a high idle when it is placed in park?

Question

For instance: ambulance arrives at the scene of an incident, sounding like a normal engine. Driver places ambulance in park and steps out, engine sounds like it is idling very fast. Why do ambulances do this?

Answer 1

The high idle is so that the lights, air conditioning, and heat do not draw down the battery. When an ambulance is on the scene of a call, the emergency lights are left on. You also want to keep the interior temperature at the optimum level for patient comfort and treatment!

Answer 2

Ambulances often have dual alternators and dual batteries to handle all the additional accessories and equipment. They have heavy duty cooling to keep the engine cool. There is often a idle air motor that kicks up the idle speed to keep the engine cool and to keep the batteries charged and the accessories functioning. You will also see this on Fire Trucks. There is a high idle that kicks in when they engage any power train output to power hydraulic and water pumps,.

Answer 3

becuase when you put an ambulance in park your releasing the flywheel and easing up on the load that would be going to The transmission. Also they need to keep rpms up slightly to get the full chargin power from the alternator becuase they run alot of diagnostic and life support equipment onboard.

Answer 4

The engine idles faster bacause it is supplying electrical power and a/c to the back where the patient is being worked on.

Answer 5

Most of the time the A/C compressor is running and the alternator has to put out enough to keep up with the onboard accessories.

Answer 6

to keep the extra equipment charged ...................