Tag Axle Wheels

[Kenny]

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

[kyle4501]

I don't know, mine have dual tires on the tag axle. 

[skipn]

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

Skip

[Kenny]

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

[skipn]

 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

[Dallas]

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

[Blacksheep]

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

[skipn]

Ace,

   Your right. I'm just being lazy. <

Skip

[gtd]

Ditto     Duals on my tag also  

MC 7 Combo

[jjrbus]

Which axle is the tag/bogie on my 5C

[DrivingMissLazy]

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

[Barn Owl]

Which axle is the tag/bogie on my 5C

After you decide where to install them, then we can tell you.

[Kenny]

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.

[Hartley]

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...

[tekebird]

it is for lower tire scuffing while cornering.