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Hey Jake, give me a brake!
Here’s the situation, you’re approaching a 6% downward grade, you flip on the Jake brake to position one and you got nothin. You then push the switch to position two and you still got nothin! You rush rearward to your plush palatial master suite and pull the cord and the main shoot fails to deploy. You immediately pull the emergency cord and again, no shoot deployment! Since you’re already in the back of the coach you climb out the window, up onto the roof, slide down the back, grab onto the rear bumper, drop to the road and apply your heels. You’re almost out off heels with little chance of slowing… What do you do?
I know there are some out there who are yelling “hey Harry you big dummy you should have tried your Jake well before the hill! But why rune a good story with the facts? OK, a story anyway!
Now for the serious question, without a Jake brake, hey give the man a break, “how do you navigate down such a hill”?
Harry
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9 Replies
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That happened to me going down the Siskiyou pass. Turned out the electronic accelerator pedal was not fully going back to zero after taking foot off accelerator. Turning off and restarting the engine (while parked :)) resets the accelerator pedal. Of course, I did not know that at the time. I went down that mountain (30 miles) as slow as I could. Still brakes got very hot. A nail biter.
What to do? You down shift manually to 2nd or 3rd gear and watch rpms like a hawk because the transmission will force an upshift around 2300 rpms. Then you are really off to the races…..
Use intermittent braking, don’t ride the brakes.
You’ll find out that diesel engines despite having high compression, have very little engine braking. Air gets compressed on compression stroke but then releases most of that energy during the working stroke. Jakes prevent that by exhausting the air once compressed. Gas engines have throttle plates that are closed when engine braking thus providing more braking.
Gerald
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Without some supplemental braking, whether Jake or retarder you have to not only anticipate steep downhill grades and drive appropriately, you also have to clearly understand your brakes are your only option for speed control and they have to be used correctly.
Obviously when approacing a steep donwhill, with or without supplemental braking you need to slow down and get into a gear appropriate for the speed. In both the 5 and 6 speed transmsissons for a 55 MPH taget top speed fourth gear seems appropriate and you need to be below 55 to drop into 4th.
When you apply brakes do not pump them. If your max target speed is 55 as soon as you are at that speed apply the brakes firmly and steady to drop to 45 for example and then release them. Allow the coach to drift up to around 55 and repeat. If you pump the brakes you run the risk of depleting the air pressure and at that point the parking (emergency) brake is going to automatically apply whther that was your intent or not. A lower gear as stated above is not going to provide much in the way of braking assistance so it is important to keep the Jake and retarder in good working order. But if they do not work you have to very carefully manage your speeds and braking application.
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Harry,
Setup 2 rip cords that You can use without leaving the cockpit. One hooked to the breakaway system on your toad. The secondary needs to be hooked to a very heavy delta style plow anchor attached with a huge chain to the rear frame of the toad. Note: if You have to use the secondary , Could possibly stretch the toad and Cause asphalt damage !Clarke power will hopefully get you fixed up. When they diagnosed the problem with mine recently. It showed a valve in the transmission was not working. The transmission guy said oh Crap , That valve cost $35000 for the part ! Luckily it turned out to be a wiring problem.
Safe travels,
Rocky -
H.J.,
Was the cruise control on at the time? Some earlier models were set up so the Jake would not come on with cruise on, unless the service brakes were applied. With the cruise off, the Jake would come on immediately.
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It also helps to have active braking provided by your toad. There are several systems available that will apply the toad brakes proportionally to the application of the coach brakes. If you have a toad but have not gotten around to installing the active brake system(s), then going down hill you have the free wheeling weight of your toad PUSHING the bus downhill faster and placing an increased load on the bus brakes when you need to apply them – read heating the only brakes you have to higher temps each time the brakes are forcefully applied.
So get out their and spend some money for a supplimental braking system for your toad, now.
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HJ,
My Jake doesn’t do a lot of good going down grades in 5th & 6th gear.
Last year out West, in Yellowstone/Tetons/Glacier, 8% grades, I downshifted to 4th, and sometimes 3rd, to avoid burning up my brakes. I had no issues maintaining my speed …
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I can’t imagine most toad brakes having much effect.
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Hi Per,
Unfortunately the cruise control doesn’t work and is part of the reason I’m going to Clark Power Services. The speed would not go above 55 mph and the cruise and Jake brake will not work. Clark thinks they are all related and thinks its a relay and I hope their right. Other things could mean big $$’s and Jon already told me that he advises, he doesn’t pay! I know, How rude! 🙂
Harry
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Hey Harry,
When I bought our coach 5 years ago, the Jakes were not working. I found that a couple of wires were unplugged under the valve covers for the master Jake units. On the 8V92 there is 2 master units and 2 slave units under each valve cover. There are other reasons for weak Jakes that appear to not work, but that was my issue.
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