Engine Hours v.s. Mileage

[Scott & Heather]

I know we aren't supposed to idle a lot in the two strokes at least, but our coaches must have idled in their day while waiting for passengers in the depots. In the 80's I'm pretty sure there weren't a lot of anti idle regulations in place quite yet so the following article I just read was interesting to say the least. If my bus comes with 500,000 on the odo or hub meter I truly wonder what that equates to in hours: taken from work truck website:

"CHATTY CHASSIS
Measuring Hours vs. Miles in Medium-Duty Truck Performance

October 23, 2013 | by Lauren Fletcher

Measuring medium-duty truck performance can help fleets more effectively manage vehicle replacement strategies, establish optimal preventive maintenance schedules, identify vehicle utilization, and ultimately calculate a fleet's total cost of ownership. However, many (rightly) contend that mileage is not a true indicator of the actual wear a vehicle is experiencing.

"There are several ways to measure performance. Mileage continues to be a popular method, but because of the variety of ways trucks are used, fleets and owners may want to consider other effective means of performance measurement, such as hours of engine operation or the gallons of fuel consumed," according to Joe Korn, senior analyst for ARI.

Tracking engine hours versus miles driven is not a new concept, but an increasingly relevant one that may still cause some confusion among fleet managers. We all know the benefit of using mileage as a performance metric. Many fleets operate under a specific year or mileage replacement policy. So, are hours an important metric for measuring medium-duty truck performance?

"As an engine idles, the wear to consume one gallon of fuel is equal to driving up to 30 miles. In these situations, it is more effective to schedule future vehicle replacements or measure lifecycle costs based on the hours of engine operation or the amount of fuel burned over a period of time," Korn said.

The main benefit of measuring certain factors by hour is using an alternative method to analyze the fleet.

"Even for delivery fleets, the miles will vary greatly across different regions, and, in many cases, the highest cents-per-mile (CPM) locations are often New York City," noted Collin Reid, truck strategic consultant for GE Capital Fleet Services. "So, cost per hour gives fleet analysts an understanding of which locations and trucks are costing more than the benchmark."

Rob Kooken, director of business development and an account executive for PHH Arval, agreed that cost-per-hour is a valuable benchmark.

"Measuring certain factors by hours vs. miles enables a fleet manager to get a more accurate insight into the wear-and-tear on a vehicle and plan preventive maintenance (PM) accordingly," he said. "For example, certain medium-duty trucks have special applications that may require the vehicle to be running — such as those equipped with power take-off (PTO). These require constant charging of the battery to operate and accrue more time idling that won't show up as mileage or utilization."

According to a recent Market Trends blog by Mike Antich, editor of Work Truck magazine, the installation of telematics devices on company vehicles began tracking hours vs. actual miles driven. This was a key turning point in the hours versus miles debate, as it provided fleets an easier way to track hours, rather than simply trusting a driver's log.

Idling — which came to the forefront thanks to telematics — is one of the main factors that can be analyzed by hours vs. miles.

"Many medium-duty truck applications perform a larger amount of their work at idle, or lower speeds, than either passenger vehicles or over-the-road trucks, and therefore will typically have low miles, but higher-than-normal hours-per-mile," explained Brian Tabel, director of marketing for Isuzu Commercial Truck of America, Inc. (ICTA).

Idling in a medium-duty fleet vehicle can use up to a half-gallon of fuel, per hour, according to www.fueleconomy.gov.

"Idling is one of the main reasons a fleet manager would want to track hours instead of mileage," said Kooken of PHH Arval. "Take an electric company truck, for example. That vehicle idles for hours each day while the crane is up. Mileage isn't being recorded during this time, but one hour of idling is equal to 25-30 miles of driving. That usage needs to be properly accounted."

Idling and PTO operation are not ideal conditions for some vehicle systems. "For example, the diesel oxidation catalyst is less likely to achieve temperatures high enough to perform optimal regenerations. More manual regeneration is required when the operating temperature is lower than a typical duty cycle," Tabel explained.

Engine hour usage creates wear-and-tear on the engine, and the usage by hour takes this into account, according to Reid. "Also, in many cases, the PM schedule would be better set with an hour guideline vs. miles, as PM ensures the engine and fuel system function," he said.

Hours or Miles?
So, what should fleet managers be measuring, and when? When determining wear in medium-duty trucks, mileage calculations can be very effective, especially for trucks driven primarily over the road.

"Mileage over time can help determine a standardized replacement schedule, which can accurately layout the overall life-of-vehicle performance and pinpoint the ideal replacement time," said Korn of ARI.

At the time, ICTA does not have a policy to directly equate engine hours to miles for service purposes, but did refer to the diesel particulate filter (DPF)-recommended service interval or 3,000 hours or 100,000 miles. "Both hours and miles are important criteria when determining service timing for a fleet," said Tabel of ICTA. "Any systems that directly interface with the engine (fuel, cooling, exhaust, etc.) would be strongly impacted by the engine hours."

Most of the experts agreed that the main factor of whether to measure by hours or miles is the truck's application.

"The more the truck is used with idle time versus drive time, the more important using cost per hour is to the fleet," said Reid of GE Capital Fleet Services. "For some fleets, you find the lower mileage units (but with higher hour usage) have more maintenance costs than the lower mileage trucks. That is because the engine wear and tear of vocational equipment is more than a truck driving on a highway."

Kooken of PHH Arval noted that the determination of tracking by hours vs. miles should be strictly based on the application of the vehicle and that specific fleet.

"If you have a vehicle that has high frequency of idling — those trucks will accrue mileage that won't show up on the speedometer. For example, I once had a client whose fleet was experiencing engine failures. The vehicles in the fleet did a lot of idling, and once we estimated the idle time, it was determined the vehicles should have had three preventive maintenance visits when, in fact, the vehicle had only one," he said.

One example would be with aerial bucket trucks. "These trucks may only need to travel a few short miles from their depot to an area where overhead work needs to be performed," said Jerry Renauer, product order support specialist for Ford Commercial Truck. "Once they arrive at their destination the mileage stops but the engine continues to run another 6-8 hours, after several weeks only a few miles may have accumulated but the hour meter tells the truth about the utilization and may be calling for an oil and filter change. Without an hour meter you start guessing when to perform this service if at all."

According to Troy Davis of Ram Truck Engineering for Chrysler, one benefit for measuring hours is for oil-change monitoring.

"Hours are intended to monitor engine maintenance scheduling (oil change, fuel filter change, air filter change, etc.) for vehicles used frequently in stationary and/or idle condition," he noted. "The benefit of measuring hours is for oil-change monitoring on vehicles that accumulate engine run time, but not many miles. Miles are typically best for other factors such as chassis, suspension, and driveline components," he noted.

Measuring a vehicle's performance can also help determine if it is being fully utilized.

"While the required level of use and need will vary among companies and industries, for the most part, mileage accumulated during a given time period can help identify vehicles that are underutilized, as well as driving patterns that might be contributing to maintenance or other issues," explained Korn of ARI. "In other cases, measuring the amount of fuel consumed or the number of engine hours can help identify more accurately the actual use of the vehicle. Regardless, measuring performance can give a fleet manager a better understanding of vehicle use, which in turn can offer insight into whether changes may or may not need to be made."

Both hours and miles are valuable metrics for medium-duty fleets to track. While miles may be best for measuring many fleet analytics, hours is an important component to ensure total visibility into all aspects of fleet maintenance and measurements.

By Lauren Fletcher"


Sent from my iPhone using Tapatalk

[Scott & Heather]

Tapatalk hiccuped and posted this three times. I locked the other threads. Waiting for a mod to delete them. Sorry. 😳


Sent from my iPhone using Tapatalk

[buswarrior]

before the regulations, they idled all day, all night, low idle, high idle, driver didn't care, neither did the owner, as long as the ca$h flowed....

To this day, I still see them idling for the 5 hours while parked at the casino...

In the big buses, count on a gallon an hour for low idle, more for high idle.
.
happy coaching!
buswarrior

[Nick Badame Refrig/ACC]

Tapatalk hiccuped and posted this three times. I locked the other threads. Waiting for a mod to delete them. Sorry. 😳


Sent from my iPhone using Tapatalk

I deleted the other posts.
Have a great day
Nick-

[Tikvah]

When I drove for a tour company in northern Michigan back in the late 80s, early 90s we often needed to keep the engine idling for days at a time.  When the weather is zero, and often well below zero, you can't shut it off.  I remember taking tours and parking for a few days at a hotel while the bus would sit outside and idle - on low.  We only used high-idle for pre-trip warm up.  Then on to the next destination for another night or two.
I know there were extended trips when the bus would run over a week and never shut down.



Sent from my iPad using Tapatalk

[lostagain]

When maintaining buses and trucks, I change the oil at 250 hrs. Less hrs for smaller engines. Whatever the manuals says. Hours has always been better than mileage.

JC

[buswarrior]

And, in our modern daze, there is no need for cold weather idling.

Proheat, Webasto and Espar, pick your OEM installed preference, all do a lovely job of getting the big diesel to roll, and keep it, and the customers, warm once fired.

If you think an idling 2 stroke wouldn't make heat for the customers.... a 4 stroke is worse.

Preventive maintenance is sketchy at best with 2nd tier fleets on down, the boiler, though installed, hasn't fired in many a year....

The fuel burn alone would quickly pay for some maintenance time.

happy coaching!
buswarrior

[HB of CJ]

Forty years ago all the fire apparatus had hour meters mounted both on the pump panels and inside the cowl by the 2 stroke Detroits.  This gave the master mechanic an idea as to how to manage maintenance.  Back then fire service was about as harsh on equipment as possible. 

This was before computers.  MUI Detroits.  High governed speeds.  No engine prelubers or block or radiator preheaters.  The mills got about 5 seconds to establish oil pressure, then full throttle was applied rowing through the Fuller T905M transmissions.  Very harsh service.  Low engine life.

[Scott & Heather]

Is there any way to calculate hours based on miles and vice versa? I new when someone says they are getting 9000 hours out of a yacht application two stroke motor what might that translate into in miles?? I know that's an impossible question. But I suspect our coaches have a ton more "miles" on them if you counted hours. According to the article I posted, 30 miles for an hour of idling. Crazy.  

Thanks nick for deleting the other posts.

Sent from my iPhone using Tapatalk

[luvrbus]

Greyhound's did idle alot,I have a stack of old service records from the Dallas terminal that shows around 220,000 miles was tops for their bus engines the 8v71's and 6v92s,idling one in the cold weather causes it to wet stack and will shorten the life by a bunch,it works that away on any diesel engine not just a 2 stroke

[buswarrior]

re: miles vs hours, a few years back, the heavy truck engine folks were throwing around a minute idling was no different than a minute driving. Trade press of the day were quoting the engineers directly, so...

That may be where the article author came up with that "30 mile" number for an urban oriented publication?

Fuel through the engine seems to be the closest measure of engine wear? (ignoring wet stacking)

Time and mileage are just approximations, or "symptoms" of the cause?

Also, for those who measure fuel economy by filling the tank, those with good air integrity and low idling get higher results.

oh, the fun we can have!!!

happy coaching!
buswarrior

[Scott & Heather]

Moral of the story...run your genny...keep your block heater going...and kill the bus motor while sitting.

[Don Fairchild]

millage over hours is an age old argument. When you look at how the buses were used back in the day they would idle around 5 hours a day between terminal unload and reload and rest/ lunch or diner brakes keeping the engine running for either heat or cooling depending on time of year. Gray had a rule with most of there repair terminals of engine replacement at 250,000 miles on the hub meter when in fact taking hours into account they had closer to 700,000 miles on them. we all know these buses were run at max power most of the time and still are, if you don't believe me stay in front of one out on the road if you can. Understand also oils, fuel and filters have changed over the years. highways have gotten better in some places. Boats almost always have hour meters on them, and should be changed at engine overhaul.

Don

[azdieselman]

Working on late model vehicles, I pay close attention to the AVG MPH. Divide the mileage by the hours. 33 or above is great. 30 down to 20 is tough on the EGR and air management systems. Below 20 is gonna cause trouble.

If the engine is working hard and being driven down the road, Use miles, If it's lightly loaded or idled a lot, use hours.
250 is a safe number.

Another issue to consider is oil dilution.

I have a 10 year old truck in the shop now, 95K, 8500hrs. He has troubles.
Engine has close to 300K equivalent miles

It's a recent purchase, I hope they didn't change the oil by miles!
He thought it was a good deal, all he saw was the odometer.

[kyle4501]

Too many differences  -

Hours idling with no load vs pulling A/C

Flat land mileage vs mountains

Light weight rig vs heavily loaded

Using full power against the governor vs partial power at a reasonable rpm.

It is difficult to equate the miles driven by different people in the same rig on the same course -- much less in different rigs on different routes.
So, equating miles driven to hours would not yield any usable, meaningful information.

Also too easy to kill a good engine with just a little abuse.