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Learning the hard way??
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Anyone allowing a downhill coach to push the revs up to 2500 is an uninvolved driver. That’s my definition and likely others are going to disagree.
http://www.dieselhub.com/specs/detroit-60-series.html
Note the max RPM is listed at 2100, with some continuous duty applications governed to 1800.
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So Jon,
Why does the placard on the side of the engine specify no load limit is 2,250, and the manual give 2,500 as the redline?
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You will have to ask Detroit Diesel that question. You are certainly able to run your engine however you wish. I prefer to err on the conservative side.
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I already did as part of our last discussion of this. They said 2,500 is perfectly safe. So would you call Tom an un-involved driver since he had his engine up to 2,300 as he stated recently?
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The unloaded, ie not making power, is 2500. The trans will automatically upshift if the 2500 limit is exceeded. The underload, ie making power, is 2150. Hope this helps.
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Well, I’m happy someone besides me is interested in getting correct information out to the PC, rather than relying on old trucker’s tales!
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Easy now Per, we old truckers learned everything sitting next to the RV Idiot table at the coffee shop.
Later
bv
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Per, you are confusing the issue. Detroit sets 2100 as a limit as was shown in the link above. But because they know some folks aren’t going to pay attention they set all kinds of limits and using sensors protect driver’s who ignore them by taking control away from them. At 2500 RPM you no longer have a choice of gear. If you drive with low coolant, high engine temps or low oil pressure the engine just shuts off. If you use the retarder excessively and transmission fluid reaches 300 degrees the retarder is disabled. None of the limits if reached are acceptable for continued driving. If you ignore the 2100 RPM limit and let the downhill push the engine RPMs up then at 2500 the transmission upshifts because like everything else Detroit is protecting the engine from a driver who is not.
Pick a gear, any gear and hold your foot flat to the floor and let me know just how many RPM’s you can reach. If 2500 is OK and you cannot get close holding your foot to the floor see if you can convince a Detroit dealer to reprogram the DDEC to limit RPMs to 2500. After all Detroit says its OK.
Are there any truck company owners on here that wouldn’t fire a driver who allows his Detroit powered truck to routinely exceed 2100?
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Bernie,
Truck drivers don’t have to worry about sitting next to idiot RVers at truck stop anymore. They take their food to go and eat it on the road while updating their log. BTW, I see you have an RV!!!!
Jon,
You are just not listening to facts. 2,100 is the limit under power. If you are stepping on the throttle in gear, the limit is 2,100. If you apply throttle with the Jake on, the Jake will disengage. If you are at 2,500+ RPM with the Jake, the transmission will upshift. If you are going downhill and building speed, it means you are going too fast for the Jake, and need to apply brakes until the transmission downshifts. Ideally you want to find a gear that requires little or no use of service brakes, while keeping RPMs below 2,500. You are just plain wrong on this, Jon!
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What some seem to be missing, is that with the Jake on, in the example of going down the hill, the engine is still under a load or making power if you prefer, just not a fuel made load / power. It still is making heat and compression, the valves are still opening and closing and there is still boost, and all the rotating parts are being used to try to slow or maintain the vehicle speed.
Seems like power being used to me.
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This discussion was had here in June & July of 2018, use search words “Mountain Driving Question”.
Here is my research from back then, for whatever it’s worth: Check out the *Notice* on p.36 of the following link for DDEC V series 60 engines.
Operators manual p.36
It states “When descending a hill with Cruise Control OFF, do not allow the engine to exceed 2,500 rpm under any conditions. Failure to observe this precaution can result in overspeeding and serious engine damage”
A decal that is on my June 1995 built DDEC III series 60 states “Max RPM NL 2225”. Also, my engine is governed to 2225 rpm.I try to never let my rpm exceed 2100 rpm for any reason.
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Mark,
When the engine is running, it is making power. When the Jake brake is used, it is absorbing power. Two totally different things. In one case it compresses air in the cylinder, then at TDC it injects fuel, which ignites in a controlled explosion (combustion), which forces the piston down with considerable force. This force creates stress on the piston, connecting rod, etc, and this force eventually drives the wheels.
With the Jake on, you have the same compression, but as the compressed air is ejected at TDC, there is no downward force. As a matter of fact, the piston will pull a vacuum, since both valves are now closed, and you have an opposite force on the piston and related components compared to the power stroke.
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We are definitely going to have to agree to disagree. I’m from the school of thought that views limitations as just that and if anyone wants to interpret things in their own way as long as I am not affected I don’t care. I do care that members understand that Detroit says “Max engine speed: 2100”
Per, run your engine any way you want.
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Per,
There are a bunch of ole truckers on here with multi million miles under their belt that have driven every conceivable combination, over dimension, stretched, doubles, triples, in all kinds of weather and terrain and did it safely because of their experience.
Instead of pissing an moaning about ole truckers you should listen to their advise and learn from their experience. The ole truckers are used to the guy that never drove anything bigger than a pickup and once in 45’ motorhome is now an expert. Those guys come and go often, it’s trucker entertainment.
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Tom,
My response was to the reference to “idiot RV” comment. I believe most of the folks on this forum are RVers, since we own RVs. Experience is good well if you know what you are talking about. I am trying to get facts out to the PC, but I keep getting pushback by folks who seem less interested in fact than their own beliefs. I challenged Jon in our last discussion to get the facts about the DD60, he was not interested. I did, and got the facts. Since Jon is unwilling to contact Detroit, how about I challenge you to get the facts? I don’t by the argument “this is what we always been told this is the way”. I prefer facts. I do have to admit, if I owned a fleet of trucks, I would probably worry about telling my operators there are three different RPM limits for a series 60.
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