| Author |
Message |
David & Lorna Schinske (Davidschinske)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, January 26, 2005 - 2:07 pm: | |
Can anyone help steer me in the right direction? Am researching air shifters for roadranger manual tranny. Only things that I have been finding via monstercrawler is for motorcycles. Can anyone give me some manufacturers or distributors so that I can get a little info on these things.
Thanks
Lorna |
Adame
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, January 26, 2005 - 3:13 pm: | |
Air shifters for motorcycles are pretty simple affairs, a whole different animal. I don't think I've ever heard of such a thing for heavy duty transmission. There are the Eaton autoshifts which use servo motors I think.
I once toyed with the idea of building a hydraulic system which used equal sized, double ended cylinders in a master-slave arrangement. The rod ends of the cylinders would be stationary and the cylinder would move the shift lever. This is done to keep the oil volume on either side of the piston equal. Four cylinders would be needed, two at right angles to move the shifter on the trans. and a similar pair at the shift lever. Leverage ratio could be adjusted by simply moving either the master or slave pair up or down the shifter or shift lever. This would be a sealed system with maybe an accumulator somewhere in the system to keep the action crisp. Shift pattern could be reversed by swapping a couple of hoses. This would be pretty simple I think. |
Henry R. Bergman, Jr. (Henryofcj)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, January 26, 2005 - 5:45 pm: | |
Air Shifts may exist for Roadrangers, but I have not a clue where one could find one. Years ago, Crown Manufacturing in Southern CA made school buses with an OPTIONAL Fuller/Eaton 5-speed air shifter.
They worked. Kinda. Most school districts removed them and returned to the single torque shift rod arrangement which was less of a nightmare to work on and worked better anyway.
Seems there was no descretion in the use of the thing--unlike a manual shifter where the driver could "feel" the shift---with an air shifter you could only "time" the shifter and move the lever.
Anyway, I only drove one example of an air shifter for a couple of dayw while my Crown was in the shop getting some maintenance. I hated it. No feel to it at all. Horrible infact.
Try www.roadranger.com and talk to the service people to sees if they have an air shifter arrangement that will work for you in a bus. They just may. At one time they were used.
Sorry. Though you would want to know the bad news. The good news is that lots of modern trucks including most cabovers use a cable shifter arrangement that is very good.
No slop, no runs, no missed shifts, no trannys destroying themselves grinding away trying to shift. Most large truck wrecking yards may have a complete cable shifter setup out of a heavy...
..truck that could be adapted to a coach with a rear mill just using longer shifter cables and more cable hangers. Sorry to rain on your parade.
Just my own opinion which can be wrong. Good luck. |
BrianMCI
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, January 26, 2005 - 8:14 pm: | |
A few months ago I was surprised when I ran across promotional literature for an airshifted Fuller 15 speed transmission...
Brian |
gusc
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, January 26, 2005 - 11:58 pm: | |
I think that truck transmissions only use air to change from one range to another. A 10sp has two ranges and a 15sp has three ranges for example so they are actually five speed trans with a range box on the back.
I never heard of an air assisted gear change but I guess anything is possible. I don't see the point since the RRs are so easy to shift and the clutch is not used except when first getting under way.
The cabover I drove had a ball on the bottom of the shift lever that slipped into and out of a socket on the trans when the cab was raised. Very simple and effective.
Chevy used a vacumn assist on cars back in the early '40s but it was a disaster when it failed, took both hands and feet on the dash to move it! |
Fred Mill (Fred_m)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, January 27, 2005 - 2:20 am: | |
Fuller did indeed make an air shifter for the roadranger, and I have the manual for it, but I was never able to find one. I finally made my own solenoid controlled air shift setup, and it shifts great, but it's hard to drive. There's no "feel" to the shifter, so you either have to use the clutch for every shift, or it jerks going into gear if the speed isn't matched exactly right. I'm currently designing an electonic control for it to act as a synchronizer to enable clutchless shifts.
Fred M |
gusc
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, January 27, 2005 - 11:54 pm: | |
Fred,
How does this work? Is it a "preselect" type where you move a lever to the gear you want and push the clutch in or let off on the fuel pedal to shift it when you're ready?
This thing puzzles me, can't even see a reason for it since all the RRs I've ever driven shifted so easily? |
Fred Mill (Fred_m)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, January 28, 2005 - 1:17 am: | |
Well, right now it's just airshifter operated by control switches. If you match the speeds right, it shifts OK, but if you miss one, it'll engage the gear anyway. Chirps the tires, and I'm afraid of twisting the driveshaft. It's tiring to drive that way. Being 40 ft. away from the engine doesn't help either.
Initially, the electronic control will be just a form of shift lockout to prevent engaging the gear until the speed is close enough to engage smoothly. You'd let off the throttle and select the next gear. It would shift to neutral, wait till the engine speed slowed to a match, then engage the gear.
The system would ultimately be capable of doing a preselect type shift, or a semi-automatic like an autoshift, if I write the software for it.
I understand the question about shifting smoothly in the truck, it puzzles me too. I took the engine and trans out of a Freightliner, it shifted much smoother in the truck than the bus. Maybe it has something to do with the short driveshaft in the bus?
Fred M |
gusc
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, January 29, 2005 - 1:11 am: | |
Fred,
I think I now understand your setup? The truck shifts smoothly because the shift lever goes directly into the trans whereas your setup is by long distance telephone! I earlier thought that you were using air to help move the shift lever but you are using air to actually do the shifting? No wonder I was confused.
I thought buses used mechanical linkages from the shift lever to the trans for both manuals and automatics?
New subject. I'm a newbie, going from airplanes to BCs for a change of scenery. I've seen some references to older GMC buses with steering column manual shifters. Did this really happen? If so are any of these still in operation and how well do/did they operate. It sounds like kind of a neat idea if it actually works ok.
Thanks,
gusc |
Greg Bush (Express)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, January 29, 2005 - 11:25 am: | |
I have one! I used it on a 15 speed rto in my
Sceinicruiser. I have changed to mechanical
lincage. My problem was the clutch was dragging,
not the shifter. This shifter has a control that
is about 5 inches square with a 4 inch shift lever. There are six gear positions with a reverse
lockout. The hi/low shift is an air switch, the
same as on a Roadranger gearshift stick, Also
has standard gearshift pattern.
The transmission part bolts on where the shift tower was. I has a shift tower like a cabover
has with two air cylinders and a valve on it.
For more info e-mail me at PD4501EXPRESS@aol.com
Greg Bush |
TWODOGS (Twodogs)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, January 29, 2005 - 11:41 am: | |
I also have an extra air shift,,it's a 12 speed spicer...normal 'H' shift pattern..then,air shift to next 4..go thru them ,then air shift to last 4...top gear is 80% overdrive...comes with the complete shifter...weighs 1000 pounds,or close to it...might do some tradeing |
Henry R. Bergman, Jr. (Henryofcj)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, January 29, 2005 - 1:43 pm: | |
David and Lorna-- About the lack of feel with the air shifter--I THINK it is caused by the length of air line required to make the thing work. Air is compressible which is the problem.
By the time the spike of air pressure hits the actual shifter thing time has passed. One can compensate for this by slightly allowing more time for the shift to happen.
With the Crown (way back in 1972) the delay was enough to throw off the driver (me) because you had to allow for more time to start the shift. You flipped the little dash shifter...
...then waited a split second before breaking torque and stabbing the clutch pedal. The best I ever got at it was "broom".....back off... shift....stab the clutch...and "CLUNK"!!
What made it worse to learn was that the gear drops were progressive...the gears got closer the higher you got. It was a Fuller T-905M if I remember right. With a 10-speed (like I have in ....
...my Crown) it might be easier to learn and do if you hit every gear as the delay timing required would be about the same. Anyway, good luck and do not be put off. Roadrangers Forever!! |
gusc
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, January 29, 2005 - 5:05 pm: | |
Henry,
You may be on to something about the long air lines.
Trucks solve delay problems on trailer brakes by using an air relay valve on the trailer. It works just like an electric relay, air from the brake pedal only has to operate the relay which requires very little air. The relay operates the trailer brakes using air from the trailer air tank near the trailer brakes.
The remaining question in my mind is if the air shifter uses enough air to cause this problem. Trailer brakes use a lot of air.
A relay might have solved Greg's problem but he has already changed to mechanical linkage.
It might help Fred with his design.
Fred,
Closer ratios are good near the top gears. This enables one to keep the rpms in the desirable range for hills and not lose so much speed. The worst RR are the 9 sp with a huge gap between 8-9. As I remember 8th top speed was around 45 but 9th would go like hell until it pulled down. |
Henry R. Bergman, Jr. (Henryofcj)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, February 01, 2005 - 6:37 pm: | |
Yeah, if my feeble memory serves me (and I kinda doubt it) the actual suggested techinque to employ the air shift was toos....
Run the mill up against the governor for an up-shift, then back off the gas pedal, stab the clutch and shift the air shift to neutral, ...
....wait a little bit of time, then select the next higher gear, then immediately stab the clutch pedal and let her rip.
If the timing was correct, (and it got quicker with each higher, closer gear in a Fuller T-905M) the air shifter would work just fine.
The problem was getting used to the different timing required for each particular up shift. Down shifting was about the same...
..only your had to bip the engine to synkronize the gears during the down shift. Anyway, it was a real hassle and I never got used to it. |
gusc
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, February 02, 2005 - 9:13 pm: | |
Henry,
I have to say that manual shifting has to be easier than what you described. My wife would never get the hang of that system and I'm not sure I would either! |