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Hendon Publishing

Hours... or Miles?

Daytona Beach, FL Police are among the first major fleets to install hour meters on their police vehicles. These Hobbs units measure total operating hours, i.e., both idling hours and driving hours. This is one of the few departments with experience in hours for police vehicles. Based on research by police fleet manager Jon Crull, in an urban setting, 100 operating hours equates to about 990 miles. In other words, around 325 hours equates to about 3,000 miles. This hours to miles ratio is typical of an urban setting. Rural police and highway patrols may reach 3,000 miles in much fewer hours.

This does not mean that the oil change can take place at 325 hours. Since urban cars idle a lot, and idling is hard on cars, the policy is to change the oil at 200 hours.

Ford Fleet has determined that one hour of idling is equal to the engine wear of driving 33 miles. Assume that 50% of the time is spent idling. In 200 hours, the odometer may show 2,000 miles, but we have to add the idling-equivalent hours, which in this case is 3,300 miles, i.e., 100 hours times 33 miles. The actual wear on the engine after 2,000 miles is really the wear after 5,300 miles, i.e., 2,000 odometer miles plus 3,300 miles idling.

Crull obtained the Hobbs hour meters from a local NAPA store. He originally mounted the meters in the dash, but not surprisingly, found some of the officers would tamper with or disconnect them. The meters are now mounted under the hood. These meters can withstand the underhood heat and moisture.

Crull finds the Ford CVPI goes between 8,000 and 10,000 hours before most major driveline failures begin to occur. The failure in this urban patrol setting is the engine and not the transmission.

Of course, these failures don’t happen in all CVPIs. And, by 10,000 hours, the cars really are worn out. Using the 50% estimate, i.e., 5,000 hours of idling or 165,000 miles is added to the 100,000 miles on the odometer to make 265,000 miles. That is worn out even for most taxis.

He still performs maintenance by miles while he is building an accurate database of preventative maintenance indicators, based on hours. And, it is admittedly easier to glance at the odometer than lift the hood to check the hour meter.

His department is still correlating hours to miles. If a significant service issue is experienced, the maintenance techs make note of both the hours and miles. Crull does, however, have some initial results worth noting...idling definitely takes its toll on engine life.

If your department uses hour meters and has a miles to hours correlation, please let Police Fleet Manager

magazine know!

Published in Police Fleet Manager, Mar/Apr 2006

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