As I move closer to acquiring a '93 U240, I am concurrently working on a PacBrake exhaust brake install. However, I may want to make a trip or two before the installation, and am concerned about the U240 lacking a retarder.
I would much appreciate anyone's anecdotal accounts of how the U240 performs on grades with downshifting and service brakes only. Does this combo suffice on longer steep grades out west? Is there added wear and tear on the CAT engine when the exhaust brake is installed and used?
If your operating with service brakes being your only resource out west then you'll want to start your descent in a low enough gear that you DONT use them. I'm thinking 3rd gear, maybe 4th depending on the grade.
I learned the hard way after 2 brake jobs. Our coach had a brake activated retarder so I had to use the brakes to take advantage of the retarder benefits..... doesn't work on down grades, not even a little bit. Works great that way in town but not on grades.
We have the joy stick now so all is good even though a trans retarder together with a Jake would be even better.
Not a direct comparison to your pac brake question but object is the same. NO BRAKES on down hill unless to brake and downshift.
Others will have to share the befits of a pac brake.
I appreciate the insights. The "start down slow" technique was what J used in my H300, even with the retarder. I shall gear the CAT down at the top in this one as well and keep it slow in 3rd or 2nd.
Thanks!
I've put an easy 15k miles in the Rockies on my coach and have never had a problem without an auxiliary brake. My front pads are still minty new. I'm on my way up to BC through Idaho as we speak.
Don't worry about it, no big deal if you know how to manage your gears and are an attentive driver.
This is encouraging. I am in North Idaho, where no matter which way you go, you're looking at a high, sometimes long, mountain pass. It is good to know that they can be traversed without an auxiliary brake. Thanks!
Elliott,
What engine do you have. Without an exhaust or engine brake, engine displacement is important in determining braking HP.
If the Cummins C engine (8.3 l), it is quite a lot larger displacement than the Caterpillar 3116 (6.6 l) which is itself larger than the Cummins B (5.9 l). And the Caterpillar 3208 (10.4 l) has a lot larger displacement than the Caterpillar 3116.
Brett,
Are you referring to compression braking without assist, with an exhaust brake, or both?
Also, are there any engine issues using the PacBrake or other exhaust brake?
More displacement/more "friction" whether with or without an exhaust brake means more braking HP. Suspect the Caterpillar 3208 (10.4 liters and 8 cylinders) would have the best braking without an exhaust brake.
As far as the exhaust brake that can be fit on a 1993 U240's Caterpillar 3116, it depends on the engine serial number. 1993 was a split year with earlier engines having weaker valve springs so less backpressure allowed. Our 1993's engine (# 2BK25862. AR 6I2481. Built Sept 29, 1992) was able to use the higher backpressure/more effective exhaust brake. No idea whether your engine was before/after the change-- build date of engine is not really closely related to when Foretravel installed it.
I do have the 3208 and ran into the same issue you mention with weaker valve springs and therefor no exhaust brakes available or it either (there was one company that apparently made them for a while but they're unobtainium now and from what I read, didn't add much value).
P.S. I'm shocked to hear the 3116 has so much less displacement. Yet more horsepower I think?
3208 could have up to 300 HP. Caterpillar 3115 all 250 HP.
And, you are correct, if the engine is not set up for much back-pressure, the exhaust brake doesn't do much.
Slow down. Run the same gear you climb in. Dont let it get control, you need to manage. Bigger brakes and aux brakes help to overcome bad situations, so just slow down and dont let it get control from you. Keep aware of your weight, get all the extra stuff out of the coach, it's more to stop. Personally I think stopping the coach is more important than pushing it faster. Overrated brake systems complemented with a retarder and a Jack brake sounds good for me. Study what you must do if you find yourself in an uncontrolled situation. Knowing how to shed speed in an emergency may save your life and others. You dont want to learn how to do this while it's happening. Pre plan your route to avoid bad downhills. Oh I have too much brakes and to many redundant ways to stop said no one ever!
Our C8.3 was built in a "transition year" when Cummins was starting to upgrade the exhaust valve springs. Researching our ESN on Cummins QuickServe, I found out our engine was built with "standard duty" valve springs. 1994 and later engines apparently came with 60 pound "heavy duty" valve springs.
According to the documentation that came with our U280, the exhaust brake on our coach is fitted with a pressure relief spring set to hold a maximum of 35 psi back pressure. If our engine had been built with the heavy duty valve springs, then they could have (back in 1993) fitted the exhaust brake with a relief spring rated to hold 54 psi back pressure. :'(
However, as I have mentioned in other threads, I have found our exhaust brake to be very helpful, even with the lower back pressure rating. Thread linked below has a bit more info on our exhaust brake, if anyone is interested. It is, of course, long out of production.
D-Celerator Exhaust Brake (https://www.foreforums.com/index.php?topic=28753.0)
Exactly. Down hill speed and up hill engine temperature are what matters. My 1981 Foretravel had a 3208 Cat and my 1993 U225 has a Cummins 5.9. Both needed to be geared down going up the grades. By using the proper gear, the Cat allowed me to go down the grades with little or no braking but the 5.9 Cummins just doesn't have the torque so I gear down and have to use the brakes. The key is keeping the speed down so you stay under control and use less brakes.
When I had the Monaco it had an exhaust brake and it worked well and now with my Foretravel I put
a Jake brake in it and I can go down hills in a higher gear. Mostly only use the Jake to hold my speed
and use the retarder to slow down for corners or for stopping and leave the brakes for emergencies
and for stopping.
My ex-Greyhound 4107 didn't have any kind of aux brake but I drove it many years including the Rockies, Mexico, Sierras without any problems. Best to be conservative and start down a hill in a lower gear than you probably need. You can always shift up. If Greyhound can do it for a couple of million miles and my coach had no accidents, that's proof it can be done. If the brakes get hot, it's too late to drop gears and the parking/emergency brake is going to do nothing so learn how to manage the hills, both up and down.
I always check air pressure at the top of a grade before I head down.
I'm spoiled with the Jake now. I just leave it on all the time but still drop one gear before I head down the east side of Donner Pass.
The bigger the engine, the better engine braking works whether in cars or coaches.
Pierce
I live in sandpoint Id and had a 93 u240 for years pulling zuki and never issues with hot brakes on passes.
Did yours have an exhaust brake?
I would have preferred a Jake (exhaust) brake when Foretravel designed the coach. The retarder works well but builds heat quickly with repeated use over a short time rendering it useless on long (and short) downhills. The Kenworth I had back in the late 90's had a Cat 3126 with a 9 speed and Jake, it was the absolute greatest when it came to downhill driving, you could run miles downhill in the mountains without touching the brakes, not to mention that great sound.
I think Foretravel was thinking of campground noise and decided the retarder would be quieter, however the retarder (not turned off: my fault) can lock up the rear wheels on a corner in the wet causing a skid, which never happened with the Jake brake.
I feel the retarder is a poor second best compared to a good exhaust brake.
I wonder would an additional cooler be possible which would extend the operational time?
David
I am surprised that a Kenworth would have the "small" Caterpillar 3126.
The Caterpillar 3126 can only be fitted with an exhaust brake (by PacBrake, Jake, etc).
While an additional transmission cooler could be fit on a retarder-equipped coach, it would need to be either thermostatically controlled OR use of an electrically operated valve so that the additional cooler is only engaged only when the retarder was operating OR with a manual valve for summer/winter.
The reason is that in cold temperatures, you could "over-cool" the transmission fluid.
It was a KW T300 with 350 or 375 hp that I custom ordered, set up as a large pickup to pull my tri axel travel trailer.