Can anyone tell me why the tag axle wheel is aligned between the two drive axle wheels? Why not align the tag axle wheel behind the outer drive axle wheel which would make for a nicer looking dual axle arrangement.
Kenny
I don't know, mine have dual tires on the tag axle. ;D
Kenny,
Oh my there are several reasons. Pick which one you like :)
1. Better traction in snow....the tag doesn't prepack for the drivers.
2. Better aerodynamics the single breaks up the air first.
3. Squirrels (gophers) don't get stuck between the duals.
Hope this helps :o
Skip
Skip, All of your reasons are great if I'm driving in reverse. The tag axle is behind the drive axle. I do like the comment about the squirrels.
Ken
Well I have always been known to be a little backwards!
Just as a note to self:
Tags on MCI behind
Tags on Eagles 05 on.... tags in front
Skip
Part of the reason is that the farther out the tag axle wheels are, the more scuffing they are going to do when going around a corner... ;)
Dallas
I thought single's in FRONT of the drives were defined as "bogies" and the one's behind were "tags" or am I all wet!
01 eagles had the singles behind the drives where as 05, 10's, 15 and 20's were all in front of the drives!
BS
Ace,
Your right. I'm just being lazy. <;)
Skip
Ditto Duals on my tag also ;D
MC 7 Combo
Which axle is the tag/bogie on my 5C ???
Quote from: jjrbus on July 11, 2008, 04:50:30 PM
Which axle is the tag/bogie on my 5C ???
If the axle is in front of the duals drive axle it is a bogie. If it is behind the drive axle, it is a tag.
Richard
QuoteWhich axle is the tag/bogie on my 5C
After you decide where to install them, then we can tell you. ;D
Okay now that we've all learned what is a tag and what is a boggie. I have an MCI9 with a tag axel (dual drive wheels in front - single wheel in back) Now back to my orginal question.
Can anyone tell me why the tag axle wheel is aligned between the two drive axle wheels? Why not align the tag axle wheel directly behind the outer drive axle wheel so both the tag and outer drive wheels are flush and in-line with each other which would make for a nicer looking dual axle arrangement.
Ok,... Theorizing (WAG)
Since the Tag on the MCI is centered to track between the duals.
Could it be a traction issue. ( where braking traction or extra support is needed.)
Could it be an engineering issue. ( MC9 tags flex side to side in turns -ie sidewall flex ) and to eliminate the chance of a sidewall blowout on the outer drive axle tire and loss of control by keeping that extra 3 tons supported in a different tread track???
Could it be to keep weight down by having a narrow close to the frame support system for the tag axle? (usually translates to money..)
All I know is that if your tags are not supporting that last 12,000 lbs of rear end weight the nose of the bus can get very squirrely. That extra braking is also handy.
As for having duals on a tag. Unless the bus was designed that way, You could just be wasting money on hauling the extra rubber which gets rubbed off in corners.
I guess it depends on where you figure the primary pivot point for steering.
on an MCI the pivot point is actually the rear axle because it carries the heaviest loads.
My guess that on buses with duals on the tags (or twin screw) the pivot point is shifted to center between the rear axles.. ( Ok, I don't know for sure on that. )
Hey, I tried to figure it out, Maybe I am completely wrong or not....Hmmmm..
Dave...
it is for lower tire scuffing while cornering.
It breaks the wind noise that would set up a harmonic after it pass between the duallys so the bus won't sound like a truck and the passengers have a smooth quiet ride ???
(watch your step on that one :D)
Also, if the tire was lined up the drivewheel would stick out way past the drive wheel. I believe the tag tracks with the front wheel though. and both tag and front tires should line up with bearing center lines.
many choices, so have you picked your reason Kenny ??? ;)
Dave correct me if I'm wrong but I thought a TWIN SCREW was referred to when a truck had tandem axles meaning two rears both with duals! Tags don't usually have a drive type rear to my knowledge so was never considered a drive axle hence being referred to as a tag! It's kind of just there rolling along supporting weight! I may be completely wrong but I was under the impression that this was the case!
BS
Are you Crown guys confused on which axle is the boogie and which is the tag on your tandem
GM spaced the front wheels wider than the rear on 4X4's for better traction.
On the 4501, you can unload the tag which will shift the pivot point forward for a shorter turning radius ;D
On a side note, a friend just drove his 4501 across the scales. ~7100# front axle & ~20,500# on both rears for a total weight of ~27,600#
Kenny,
So far you have 2 posts for wheel scuffing prevention. If you are considering
moving the bogies out I might reconsider.....if you are going to be driving in snow.
Snow/ice chunks can build up behind the duals and when they finally break off
you could have quit a bump in the road :)
Sorry we weren't great help
Skip
Quote from: Blacksheep on July 17, 2008, 04:35:09 AM
Dave correct me if I'm wrong but I thought a TWIN SCREW was referred to when a truck had tandem axles meaning two rears both with duals! Tags don't usually have a drive type rear to my knowledge so was never considered a drive axle hence being referred to as a tag! It's kind of just there rolling along supporting weight! I may be completely wrong but I was under the impression that this was the case!
BS
I was referring to a tandem or dual drive axle configuration. Ie: Crown and I think the Flx VL100? (someone said that a while back??) or was it a mexican dina/sultana???
The Scenicruiser had dual wheels on their tags but still only a single drive axle.
However that works out, The MCI tag being offset might allow the use of a Big Single
configuration, Not that its needed but someone will bite that bullet playing around to make
stuff look neat.
Don't mind me, I am crazy anyway..
Dave...
Quote from: Blacksheep on July 17, 2008, 04:35:09 AM
Dave correct me if I'm wrong but I thought a TWIN SCREW was referred to when a truck had tandem axles meaning two rears both with duals! Tags don't usually have a drive type rear to my knowledge so was never considered a drive axle hence being referred to as a tag! It's kind of just there rolling along supporting weight! I may be completely wrong but I was under the impression that this was the case!
BS
Ace, Twin Screw is the standard nomenclature in the trucking industry for a tractor that has 2 differentials, one on each axle. Both Differentials don't always pull at the same time, there is a switch on the dash called a "Power Divider" or a "Differential Interlock". The term really has nothing to do with the number of tires on the axles.... I had a quad Axle, triple screw set up with 2 tags both of which raised off the ground to increase traction, ( a real PITA to keep up maintenance wise).
Mostly the Power Divider supplies power to the rear drive axle until the switch is engaged which then allows a gear to lock in the front axle. This is used mostly for getting unstuck from slick spots or snowy/icy hills.
If anyone is interested, there was also a system called "Belt Drive" which is just what the name implies.. there was a big belt between the drive axle and the tag axle(which had duals on it), and the theory was that when you were driving around in less than ideal conditions, the tag would act like a drive axle and get you loose.... It didn't work well at all to say the least. Just another idea thought up by an engineer who thought the numbers crunched showed that it was a great idea.
What actually happened was that there was no way to keep the belt tight between the axles so, after a couple of thousand miles of running around on highway and out in the muddy lettuce fields, the belt was so worn that when it came time for it to do it's job, it was too loose to provide friction to the tag axle.
Here's another question.... has any one ever seen a Mack with a tandem axle, with hard rubber tires and a chain drive to both axles?Dallas
Dallas
MAC or REO 2 ton coal truck?
Skip
Quote from: skipn on July 17, 2008, 09:47:50 AM
Dallas
MAC or REO 2 ton coal truck?
Skip
The one we had was a Mack, 1915 Vintage that had originally been built for use by the U.S.Army for service in the "Great War to end all Wars".
Now, do you know which side to stand on to crank the engine with the hand crank? ;)
Dallas
I believe it was to the left of the crank. That way you are pulling up on the handle. If the engine backfired, as many did, then it would only rip the crank handle out of your hand rather than breaking your arm.
Along with the thumb under the pull or your arm will receive the backfired kick.
Learned that from 4-H tractor club during late 40's.
Sojourn for Christ, Jerry
Kenny
I don't know why they made the offset like they did, but I agree with the looks.
When I made all the changes on my Eagle, I had the air lift tag axle built to the
same dimension as my drive axle and turned the tag wheel out to align with
my drive wheels. Also I could run duals on the tag if i wanted to, The Mfg. said
I would loose about 25% of the carrying capacity, but this wasn't a problem since
the tag was rated at 25,000 Lbs. I have put almost 70,000 miles on this setup
and have not noticed any more tire wear than normal.
Catskinner!
Sonnie Gray
73 0/5 Eagle 3406 Cat
Pottsboro, Texas
Dallas, I wasn't saying that because each axle has 2 tires was referred to as a "twin screw! What I always was told was a truck that has 2 axles, both with dual wheels, and each axle having it's own drive gear/rear was referred to as a "twin screw", hence the 2 seperate rear ends! In fact, I think there could have even been some dual axle, both with drive rear ends with single tires instead of duals back in the day!
BS
Kenny it must be a MCI thing they do not look good to me and I don't know the reasoning behind it the Eagle 01 made in the 60's had the tag matched with outside driver wheel and the MOL built Eagles with the air lift tag were align with outside driver and so is the model 25
How about aligning the tags soossss they will miss most (some?) of the sharp stuff that gets tossed up by the front drivers? I know on my old 10-wheeler Crown Super Coach the rear duels were more apt to get flats from stuff run over safely by the front duels, then flipped back onto/into the rears. Dunno if the tags wore out any quicker; don't remember. Too long ago. :) :) :)
Thanks for all the feedback. Just wanted to know if maybe I made a mistake. My MCI9 now has the outside of the tag wheels aligned flush with the outer drive wheels. Had a custom set of wheels made with a custom offset to bring the tag wheel out flush with the drive wheel. Then dressed all the wheels up with identicle wheel covers. Take a look at the pictures. (I hope the pictures get attached)
Kenny
Kenny,
I think it looks good.
From what I can tell nice looking bus but where is the engine?
SKip
The engine back there somewhere. Rear skins are removed due to restructuring for a super towing hitch (10,000 lb), modified cooling and 18" rear extension. Not quit finished yet but had to do something about the wheels. I think you can have the uglyest vehicle in the world, but with the right set of wheels it will be beautiful. By the way, the last picture was with the orginal wheels.
Kenny
Sorry but I am a curious sort......
Ok you let the cat out of the bag......18" extension 10k hitch?
Will/have you extend the rear cap back 18"?
I do hope you are taking pictures to share with us. :)
Skip.
Skip, It all started out with wanting to add a hitch to pull a 10,000lb trailer. After reading many posts relating to hitches, their capacities and cracked engine cradles, I wanted to take no chances. After studying the structure of the bus I designed a structure that ties into the engine cradle, roof structure and sign board. It turned into a bigger project than I thought in that it involved removing all the rear skins and rear structure. See pictures. From there I extended the engine cradle and added the rest of the structure. Just as it was barely completed, we took off for Sturgis SD (2500 mile round trip) with a 7,000lb trailer. Trailer pulled like a dream. The rear structure is also designed to add a lift for my Harley (900lbs) to hang off the back of the bus. The 900lb, $20,000 Harley was probally my biggest concern for doing it my way.
Kenny
Kenny,
Thanks muchly for the pict and info.
Looks like a lot of work but very well done.....when you get there
I would love a pict on the harley cradle with the harley on it!
I'm debating on what it would take to beef up my hitch setup.
Probably a next year type project but I'm learning.........
Skip
You should have bought an 01 Eagle. Mine line up just perfect! ::)
Seriously, you are probably making the strongest hitch ever created by man for a bus. What an undertaking. My hats off to you!
Paul