AutoShift Problems – now general discussion on AutoShift and Clutch Systems

[Bob Belter]

Ahoy, All,

Clutches !!!!  I know a LOT about clutch actuation, which I have written up previously here or on the Eagle web site.  You may be able to chase it down.  In summary:

1: An air operated clutch will NOT work OK with a modern double disc clutch  --  Been There Done That.  I'm now hydraulic.
2: If you use one wire hydraulic hose, allow for a travel loss due to diametric expansion  ---  I Now use 1/2"   SS tube   --- BTDT
3: IF you need to double clutch (I do --  some times) note that small tubes/hoses will probably be too slow.  ---  BTDT
4: If you want to speed - up the slow clutch by thinning the fluid,  --  Plan on a slipping clutch because of cylinder friction holding-up the clutch.  BTDT
5: And other stuff which I've forgotten.

Jim and I both know that being experienced engineers does not make us exempt from doing dumb things that we have to fix.

All - in - all:  MARVELOUS entertainment.

Enjoy   /s/   Bob

[luvrbus]

Bob, that one reason I suggested Prevost they did it for you from the master cylinder to the slave cylinder and even the line size. 


good luck

[robertglines1]

off of Jims problem...Bob (Xl45E)going to autoshift...will use prevost factory set up.The passage front to back is installed already just have to add hardware and pedal...definitely the way to go for me...probably 3 weeks off from that project ;will let you know more about set up when it arrives...cost etc..

[rusty]

Where is a good source to get these prevost parts? Do I have to worry about cross contamination when I but them in my Eagle?

Thank You Wayne

[rv_safetyman]

First of all, I never expected to see this thread come back to the top so many times.  Each time I read the part about "home on the hook", my heart skipped a beat, so I changed it

All of us that have gone through this exercise (Brian Diehl, Bob Belter, Bruce Stude, etc.) have spent a lot of time talking about our present system and what we would change.  It is simple to buy an automotive master cylinder and some sort of slave cylinder.  Several of us are using Volvo slave cylinder and the matching clutch arm (very short throw).  The issue is leverage.  I played with three different size master cylinders trying to get reasonable pedal pressure (the old knees are not what they used to be). 

Everyone that has tried a pure air system agrees that it just does not work.  Brian uses a 12V vacuum pump and an automotive master cylinder with the large vacuum boost chamber.  I think Bruce uses the same system, but with a 120 volt vacuum pump.  Bob's system is very unique with a rather complicated air assist.  I use a brake treadle valve and air brake chamber.  Very easy pedal, but terrible "feel" (can't tell when the clutch is engaging).  I have overcome that with my hand lever clutch system where I no longer use the lever to push on the hydraulic cylinder, but rather as an indicator of "clutch pedal travel".  That is very clunky, but it works for me right now and I have gotten pretty good at smooth clutch engagement.  However, no one else could easily drive the bus.

Brian and I have talked about use a hydroboost master cylinder.  That system is a very powerful brake boost system that uses power steering hydraulic pressure to apply controlled force to the master cylinder.  A reference is:  http://www.hydratechbraking.com/Hydratech/tech.html.  It is fairly compact and has tremendous force multiplication.  Many four wheel folks with huge tires make the conversion in an attempt to get adequate braking. 

The issue that we faced, was "breaking" into the critical PS system.  I am getting pretty close to having my hydraulic fan system installed, and I might think about using the non-priority side of the pump (fan side) as a source.  The other issue is somehow making sure that the huge pressure capability does not damage any of the clutch linkage.

Bob mentions the use of tubing vs hose.  If you use hose, you MUST use two wire hose so that there is no expansion in the long hose length.  That way, you can also use larger size hose to avoid sluggish engagement. 

Guess I better quit for now before you all go to sleep.

Jim

[robertglines1]

Jim we have a 10,000 winch that is hydraulic is spliced into the powersteering pump on our 550 ford.works great and doesn't effect steering.spliced into line between pump and power steering unit.

[rv_safetyman]

Bob, for some reason it is easy for me to picture tapping into the PS line in a car or relatively small truck.  Indeed, it is an OEM installation on many vehicles.  For the OEM installation, I would suspect the pump has both a priority and auxiliary system or some other system to make sure the PS had a hydraulic supply in the event of a hydroboost line failure, but I don't know that for sure.

However, I can't get my mind around a huge bus with no power steering.  Yes, I know that there are lots of mechanical PS buses, but I don't know if a bus with a PS box (a different animal) could be steered effectively in an emergency.  Probably no problem. 

The other issue is altering the PS on a big vehicle might not look so good if a accident occurred and you were drug into to court.

Jim

[bs4104]

I used a Volvo truck master cylinder under the floor behind the left head light. 1/4 steel brake line front to back & slave cylinder from a jeep. then add a air assist to it.It helped but then went to a hydro-vac booster with 110 V. pump for less noise.  Bruce

[bs4104]

 more photos. Bruce

[luvrbus]

Jim, if you go the booster route I have a 12v Blue Line vacuum pump new in the box.


good luck

[Brian Diehl]

One of the things to note about Bruce's setup is he has the Eaton easy clutch.  I however, have the standard truck clutch.  The easy clutch is a very nice animal and changes the force dynamics.  The farther you press on the pedal the less force it takes unlike the normal setup where it gets harder the farther you press in the clutch.

[rv_safetyman]

Brian, I also have an Easy Clutch.  It was still very hard to push with my pure hydraulic system.  I built a bracket for the Volvo pedal and MC.  I had to modify the geometry just a bit.  I did not think the change in geometry was significant, but the geometry is very subtle and the linkage arms are quite short.  In any case, the pedal force just killed me (and I still have fairly strong legs for an old fart).

Clifford, in order to use a vacuum system, I would have to go back to some sort of clutch pedal system (as opposed to my air over hydraulic system).  I keep thinking of a good way to do that.  The closest I can come to a pedal mechanism is a clutch pedal pivoted under the floor close to the middle of the driver seat with a push rod and cranks down to the MC.  However, all the electrical is there.  I think that is how Bob's clutch is set up (model 1?).  Thanks for the offer.  Bruce has offered a vacuum pump like the one in his pictures.

Given all of the other issues I am facing, the clutch project seems to be far down the list.

Jim

[Hard Headed Ken]

I purchased a wrecked trucked with an Eaton Ultrashift and Series 60 that I'm installing in my 1988 Prevost. The setup has about 250,000 miles on it. I wish that I had put all those miles on it instead of the 5 or so that I did while it was still in the wrecked truck. Then I could give an experienced assessment of the durability and operation of the centrifugal clutch that is used in the Ultrashift. If I combine the demo ride I took in a new truck with the Ultrshift, the research I did on the truck forums and my 5 miles or so in the wrecked truck (which was mostly trying to simulate backing up to trailer or making sure it shifted through all the gears). I think I'm going to be pleased with the Ultrashift. It seems the clutch version could be a little smoother backing up, The Ultrashift was a little jerky in R1, but hardly noticeably in R2 and this was an unloaded road tractor cab/chassis only. I think the 40,000 lb bus will make it smoother, who knows it maybe worse. I'll know in another month or so. I asked myself, how often do I back up and hook to a trailer anyway? I know a clutch has some advantages. I had a bus with a clutch and shifter and I'm trying to avoid both of those components. I think if you want a clutch or a shifter then you should have either or both, after all that's why we have red ones, green ones, GMC ones, Eagle ones and so on. Jim, if you haven't found your problem yet, stay after it. let's keep those electrons flowing and keep making things as complicated as possible. One other thing Jim that I almost forgot. I using green pond water for antifreeze, it's cheap and available near most major highways hear in the south. I know it's the best, don't try to change my mind.

Ken

[bs4104]

Ken with the Ultrashift you might want to have a starter over ride switch for starting up in gear because  if it is shut down or kill in gear you might not be able to get back in neutral to start it back up (bound up in a gear). Bruce

[Brian Diehl]

I using green pond water for antifreeze, it's cheap and available near most major highways hear in the south. I know it's the best, don't try to change my mind.

Ken

Hey Ken, did you happen to include a green sludge filter in your coolant system?  Those green sludge filters can extend the life of the green pond water another day or so.  I've found them extremely worth while and carry about a hundred or so spares to "have on hand"!  :-)