Engine Brakes

[redtrucks]

Does NFPA require a engine brake for all apparatus over 25,000 LBS?

[efd281]

NFPA only requires a secondary braking system on the apparatus. It could be any number of systems: engine brake, exhast brake, transmission retarder. It is just that many manufacturers include the engine brake as a standard feature because they come included with many engines.

[FWDbuff]

The NFPA doesnt require anything.

[FYRTRUCKGUY2]

This post and many others could be resolved by simply reading the standards. I will once again jump on the band wagon and suggest that NFPA should apply for a grant to distribute one copy of a standards book to a department when purchasing a particular piece of apparatus such as "pumping fire apparatus", "mobile water supply apparatus", yada yada..... Because it is ever increasing apparent that Departments do not want to spend the money to get copies and pay NFPA for them!

NFPA "DOES" suggest (I prefer to say require, but that po's some people, but thats ok, they can spend their time in court when something bad happens) that any vehicle "over" 35,000# GVWR requires an auxilliary braking device. These of course come in many variations. If you surf around, you will notice that most manufacturers design their "program trucks" on the 35,000# GVWR to avoid having to raise the prices to include the auxillairy braking devices, LOL!

The smaller horsepower engines, such as: The International, Cummins and Caterpilars that are 330 hp and under (again typically) cannot accept the engine compression brakes (ie: as most know as a "Jake" brake), but rather use exhaust brakes (several manufacturers of these devices) as a means to comply with the standards over 35,000#.

There is an exception to that rule that I truly think is a nice option for smaller engines. That being the Mercedes engine in the 300-330 hp class and standard in the Freightliner, is available with both the exhaust brake and a compression brake alone or comnined together. The engine compression brakes provide significantly more stopping performnace than the exhaust brakes to the current year manufacture.

Typically when you get above the 330-350 range of engines and go to the ISL (350-400hp), ISM (400-525hp) Cummins, Series 60 (430-525hp) Detroits, Big Block (425-525hp) Cats, the engine compression brakes are available on all. I might suggest that a decent middle of the road product is the Cummins ISL thats is typically used in the 370-400 hp range, couples with a 3000 Series MD transmission (saving significant money verses jumping up to the 4000 series HD). That combination to 400 hp currently is cool because you get the HP and the compression brake availability and keep prices in control.

There are tons of components offered, but each manufacturer may or may not offer them, due to their engine compartment envelope accepting the particular engine or if the engine enclosures will accept a large enough radiator to cool that engine. It will get tougher with the new engine emissions standards we will all face by 2007, but the innovative American spirit will figure out how to make the engines work with the new standards.

Bottom line, trucks that are above that 35K "range" need auxillary braking devices. It may sound as though I forgot something in that there are driveline retarders (ie: Telma's) and transmission retarders, but I did not mention them for a reason. They continue to pose strenuous scenarios for both alternators, and transmission heat. They are out there, just go look.

Stay safe and have fun.

GUY

[Bones42]

On a side note, to go along with FYRTRUCKGUY2's thought about everyone having a copy of NFPA standards, we asked our local library (which is FAR from big) to get a set that we can "check out" when needed. They were happy to oblige. Our cost - $0. And we now have the standards available.

[redtrucks]

Thanks for all of the info! Our department does not have any books regarding NFPA guidlines. Asking the libary to stock these books is a good idea. That way it could benifit more than one department.

[fdmhbozz]

I, personally, would not spec any fire apparatus without some form of secondary braking system. On the bigger trucks, like the engines, that would be an engine compression brake. On the smaller ones, like the ambulance and command vehicles, it would be the exhaust brake.

And they would all be made by the Jacobs company.

There is nothing cooler than a Jake on a PSD Ford truck.

[lvwrench]

Fyrtruckguys answer is awesome and says it all. Better safe than sorry. We use em.

[Dave1983]

We have engine brakes on our new quint and pumper, a retarder on our reserve pumper and an exhaust brake on our squad. For stopping power, I like the retarder, but you have to be VERY careful with it on wet roads (more so then the other types).

[BirkenVogt]

Modern retarders have issues. They make it mandatory to replace the transmission oil cooler every 3 years or so (Pierce and Spartan and maybe some others came out with bulletins on this a while back). They also add a tremendous heat load to the engine cooling system which can make it difficult to keep cool with certain chassis under certain conditions. A Jake on the other hand heats up nothing but the air going through the motor and so is a much better choice in my opinion as a mechanic.

As mentioned earlier Mercedes' "constant throttle" engine brake is also very effective as is the International version which I believe is offered on the 466 as well as the 570 now. Same deal, only heats the air going through the motor. And if the noise of a true Jake is an issue there are mufflers available that will completely silence it.

"Just say no" to transmission oil retarders, they are a silly solution to a problem that has been around since the glory days of trucking, and has always been solved in the commercial world by the application of Jakes or the like.

Birken

[Murph64]

Originally posted by BirkenVogt
And if the noise of a true Jake is an issue there are mufflers available that will completely silence it.

Tell me you're kidding, and people like this really don't exist...



Andy

[Stuart]

Do a google search for 'Donaldson Silent Partner'

[tkakuris]

We have a new Pierce Aerial, 100'. Weighs about 72,000lbs. We have a Jake Brake and a Transmission Output Retarder. Saves us on brakes. Both work great. The jake is not as loud as some of our older rigs. With both on full it takes us down a 10% grade at 15mph with no service brake usage.

[Fire304]

The issue of no NFPA books is complicated by the fact that NFPA has been on a revision binge the last few years. Buy a complete set and it'll be out of date in 6 months. The real problem is that NFPA wants to make a profit off their work rather than act as a self-less organization who's sole function is to provide for the safety of firefighters and fire related equipment. You can't even find a synapsis of individual NFPA standards beyond the name of the standard on their web site. Look up NFPA 1911, a hugely important standard to us and all you'll get is :

Document Scope: This standard shall cover the service testing of fire pump systems on automotive fire apparatus.

Well that was usefull information wasn't it? If you want to buy just 1911 it'll cost you $50. A complete set of codes is $1200, for some departments that's a significant chunk of their discretionary budget. My local library system is so strapped for cash they've closed some branch libraries and reduced hours at all others. Asking for a $1200 set of books that 20 people are ever likely to need through is unrealistic.

Tranny retarders have their place, they are quiet, simple to use, and can be turned on and off without damaging the system. They are very common in coach busses where you can adjust the amount of breaking force on the fly. Do that with a Jake a few times and there'll be a pile of parts lying in the road to mark the exact spot you shifted the retarder while decelerating. With proper maintenance (basically an excellerated oil and filter PM schedule) they should last the life of the truck. Anyone who tells you you have to replace the oil cooler just because of the age is soaking you.

Electric driveline brakes are also an option, although I've yet to see one, and I wonder how well they'd take a New England winter.

To the best of my knowlege Pierce and E-One (who control the vast majority of the market) do not offer a stock Class A pumper at less than 40,000lbs GVWR. I've seen a few commercial chassis come through around 38,000lbs but none lighter.

It is possible to get under that weight but you'll be sacraficing a lot and paying for it as well.

[Murph64]

Originally posted by Fire304


Tranny retarders have their place, they are quiet, simple to use, and can be turned on and off without damaging the system. They are very common in coach busses where you can adjust the amount of breaking force on the fly. Do that with a Jake a few times and there'll be a pile of parts lying in the road to mark the exact spot you shifted the retarder while decelerating

??

So a Jake should not be turned off and on? Please 'splain to me what it will destroy, and how.


Andy

[Fire304]

A true Jake Brake engine retarter works by opening the exhaust valves prematurely and dumps the compression from the engine before fuel is injected. If you switch the jake on or increase its setting (which increases the number of cylinders being used) while you are decelerating you risk trying to push a valve open while the piston is at higher pressure during or after firing but before the power stroke is complete. There are safeties built into the system (it uses oil pressure which takes a second to build up) but repeated misuse can result in valve or cam shaft damage.

You should only turn on or adjust the retarter while at a full stop or while accelerating (the brake will not activating while acclerating). Also, since engine oil is used, Jacobs recommends you do not use the brake until the oil is up to operating temp (yeah right).

An exhaust brake which uses a butterfly valve in the exhuast is not subject to this, but you only have 2 settings, on or off.

A tranny retarder can have a dozen settings and can be changed while you are coasting down a hill to maintain your speed.

[nmfire]

We had a tanker with a jake and no muffler. I swear you could shatter windows with it going down a hill. It's not quite as bad with a muffler but still quite pronounced.

Our newest rescue has a jake that is VERY quiet and VERY effective.

[Res343cue]

Originally posted by nmfire
Our newest rescue has a jake that is VERY quiet and VERY effective.

Then it aint a Jake if it's quiet.

[SSHANK42]

The only thing that sounds better than a jake is the sound of a good old fashion 4 barrel carb. sucking massive amounts of fuel and air.

[Fire304]

SSHANK, LOL I loved my old 67 Skylark, used to flip the lid over on the breather so I could hear that sound.

While I was at the Jake web site the other day I saw they had a new product called a bleeder brake. Effectively it works the same way as a regular Jake, but rather that poping the exhaust valve wide open at the top of the compression stroke it cracks it open a little, only much earlier in the stroke. End result, compressed air bleeds out slower and there is not the loud roar we associate with the Jake. It is being made for medium engines which have not been able to take a full jake in the past from class 2 to 7 vehicles. This might be the product nmfire's engine has, do you remeber what engine you've got in that rescue? By chance if the rig an Internation? The bleeder is an option on 466 and 570 engines sold at Diamond Logic Engine Brake.

http://www.jakebrake.com/content.php4?doc_uid=145