Here's a couple videos on using a Jake Brake , The first one is from a trucker with 35 years of experience. The second one is a trucker using a Jake inside a tunnel with straight pipes. How do you use your Jake if you have one?
Nice guitar intro. http://www.youtube.com/watch?v=ySw2G3Lkqf0
The second one is for fun, please excuse the French at the end! :))
http://www.youtube.com/watch?v=Pokpfj6ZF90
Jerry
Jerry,
Fun videos but had to cover Koda's ears for the language at the end of the last one. :D
Clessie L. Cummins invented the Jacobs brake back in 1930 but it was not sold until 1961 and naturally started with the Cummins Diesels and then quickly put into service on the Detroit 71 series. He also invented the Jacobs chuck found on drills.
Don't know if any Foretravels aside from the 2 cycles have Jakes. His tips are more for a 4 cycle owner with the exception of letting the engine be up to operating temps before using it.
The Jake on 2-cycles is much more effective at the mid to high RPM range and the vibration he talks about just is not present on the Detroits from idle to fuel cutoff. The music for the video would not be C&W but classical if it featured a 92 series. ;) I never can resist opening the driver's window while going through a tunnel and listening to the Detroit/Jake music. The ample muffler on our U300 makes use of the Jake in residential areas possible without incurring the wrath of the locals.
Living in the Sierras, I leave it switched on all the time as it's either full throttle or Jake brake with few flat spots for more than a few seconds. Driving with an Allison mean you are never quite sure what gear you are in at low speeds when starting down a steep two lane mountain road. If it looks really steep, I usually pull over and punch in either first or second gear and then get it rolling. Otherwise, the Allison may not shift down to a lower gear until it picks up some speed and then quite suddenly. Interstates are rarely steep so it does not get much use. In the case of I-80 eastbound over Donner Summit, I downshift to 3rd (4 speed Allison) and head down to Truckee at about 55 mph using the service brakes 3 to 5 times to slow to 50 or so before letting it gather more speed. With a 2100 rpm max, I don't let it go over 2000 before using the service brakes to slow it two or three hundred rpm. Westbound down I-80 from the summit is a non-event and usually the aerodynamic drag is enough to keep the speed in check until we get to the Highway 20 turnoff.
Using the not RV recommended road down into Jackson, Wy, was a second gear decent with fairly frequent use of the air brakes. They work well and while warm at the bottom, never faded at all. Always good to check air pressure before starting any decent.
I believe a retarder/Jake brake is meant to support the service brakes not the other way around. Using the retarder rather than the service brakes could be part of the reason some get sticking calipers. Proper selection of the right gear along with the Jake make a safe and easy decent of any grade. You can always shift up if you end up going too slowly but slowing to shift down if going too fast with hot brakes can be difficult.
Even the infamous I-5 Grapevine is easily descended without any fuss if you plan ahead, watch your speed, rpm and air pressure. You never want to be the first one to the bottom. NEVER let the cars behind dictate your decent speed.
Pierce
Thanks Pierce, expert advice from an expert!
Were headed up to Birmingham ( Pelham, Al) to Oak Mountain State Park Oak Mountain State Park | Alapark (http://www.alapark.com/oak-mountain-state-park) for some R &R and to bring Max our Golden Retriever back for a visit with his adoption mother. Adopt a Golden Birmingham - A golden retriever rescue organization serving... (http://adoptagoldenbirmingham.com/)
I'll be using the Jake going through the Mobile Tunnel. Yipee! ^.^d
Jerry
We have a Pacbrake which is an exhaust brake but not as much braking action as a Jake has. Even so, I would hate to be in the mountains without it. The Pacbrake is more effective at highway speeds and is practically non-existent at anything below 35mph. Nevertheless, I descend Snoqualmie Pass (east of Seattle) at 55mph with only a few touches on the air brakes with the Pacbrake engaged from the summit (a switch on the dashboard turns it on or off). Other motor homes around me are constantly on their service brakes all the way down. (The Pacbrake does not make the brake lights turn on, which is not an issue given the relatively gentle braking action but if it were firmer action it could be an issue on a crowded highway.)
I agree with Pierce that the auxiliary braking is there to augment the service brakes but I also use the Pacbrake to simply hold a speed on a descent without using the service brakes a lot.
I do engage the Pacbrake when exiting the freeway because every little bit helps and you never know what you're going to find on an exit ramp; or how short it's going to be.
By the way, we get a lot of vibration at idle with the Pacbrake engaged. The Pacbrake is very quiet, by the way... very hard to know if it's engaged just by listening to it. Even hard to tell when it's on and braking; subtle deceleration and no noise. But actually quite effective. The version I have was installed by the original owner of the coach (along with the Banks package) and the newer versions have more firm braking. Relatively easy installation as long as you can get easy access to the top of the engine.
Craig
Thanks for the pat on the back but like everyone else, I learn something new in almost every hour while underway in our coach. Just when you think you know it all, complacency rears it's head and gives you a bite. I think Tennessee Ernie Ford had it about right with our 16 ton Foretravel and the company store. :D Driving 16 tons down the road does give the driver more responsibility to be especially aware of conditions that don't effect the average car driver.
Craig, yes, nice to head down a long interstate grade where you gradually pick up speed to the point where you might want to tap the brakes for a moment but the Pac Brake or Jake makes it easy. Off ramps are nice to have that little extra automatic braking. Part of the learning process is judging how short the off ramp is, whether downhill or has a sudden turn before a stop sign and if at night, downshifting and approaching with a little more care than in daylight. Wet weather should start the process a few hundred yards sooner.
For those new to our Detroit engined Foretravel with a Jake, the factory (at least in our case) used a dash switch for the Jake function with the "retarder" letters still in place. It has two positions. The first uses just the exhaust valves on the curb side of the engine with the second using both sides of the engine. Sometimes while on a long downhill in fourth gear with the speed just creeping up, I will use the first position to keep the speed steady at about 1500 rpm/60 mph.
As far as maintenance goes, I remember a DD seminar back in the early 1970's where the factory guys did say that the use of the Jake could cause the supply or return lines on an injector to loosen if not properly torqued and allow diesel fuel to contaminate the engine oil. When fueling, it's good to check engine oil and if a little higher than expected, smell the dipstick for a diesel odor. Not a bad idea for 4 stroke diesel owner to do the same as the mechanical fuel lift pumps with a bad diaphragm can also introduce fuel into the crankcase.
Pierce
Goodness, you rednecks would have loved the 12V-71 DD in the MCI with poor mufflers in a tunnel at 2500 rpm, sure creates panic, only did it once in a tunnel. :giggle:
I know of a 1995 U300 with cat and jake brake
You didn't need a tunnel in Mexico where every bus had a Detroit with no turbo to keep the noise down and just a 90 degree bend for two straight pipes out the back. You could hear them miles away. Much worse were the under powered and overweight trucks climbing two lane grades at 10 mph smoking like trains.
How things can change in a few years with the likes of Peterbilt, Kenworth, Freightliner, GM crew cab P.U.s, etc built down there today.
Pierce
I have the JAKE on my M11 Cummins.
I keep it on almost all the time. It works GREAT!
I have the Jake on my M11 and you can barely hear it any time - including a tunnel. Mine as an early 95 is wired as a one speed - applies all 6 cylinders. Later models were wired as two speeds with a 3/6 cyl high/low.