Mack Camelback Articulation

[sodly]

I was searching the web for photos or video demonstrating the articulation of Mack's famous camelback suspension.  Surprisingly, I couldn't find much of anything.  I was surprised.  The only thing I can find is the old photo/illustration of the bogie by itself from old brochures.  No photos/videos of actual trucks in extreme articulation conditions.  Anybody got anything?

[j hancock]

Mack L model camel back suspension articulating.

[sodly]

When the suspension flexes like that do the main spring packs stay basically parallel with the sides of the frame?  Or do the springs themselves twist with the axles?  I've never seen this clearly.

[41chevy]

The spring packs pivot in a parallel arc on the trunion shaft, the rears are mounted on the ends of the springs in rubber or poly isolator blocks and have  the ability to "twist" on the springs. Numbers 11,12,13 and 14 in schematic.

 

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[6v71]

Don't know too much about the camel back suspension, but I'm very familiar  with the the older military 6x6 set-up and they appear to be basically the same minus the rubber blocks on the spring tips and a slightly  different arrangement of the torsion bars.  Spring packs swinging on a trunnion shaft with axles mounted on spring tips.  If you just want to see the system in action, you might have better luck looking a footage of military trucks crawling through rough terrain.

[Vladislav]

The main difference between those military Timken setup (and many others) and Mack Camelback is the attachment of the spring ends to the axles.

Or more correctly to explain, the way axles of the bogie are designed to be kept in their place. Generally you need to have them both not moving front/back and side ways and not to turn over themselves.

Usually 6 or 8 torque rods are used. 4 basic ones - 2 to each axle near the ends to connect to the central crossmember. Than two or four mounted higher, usually at the carrier housing, which working together with the lower pair prevent the axle from turning over.

Mack Camelback is a bit another story. Mack uses only two torque rods. The upper ones. The role of the lower set of rods is played by the spring packs. They are attached to the axle housings and don't allow them to travel. As long as articulation of the bogie must be realized the spring ends are suited between two rubber pads which allow the springs to twist in them a little bit.

When a vehicle turns its axles might be forced to go sideways. In most tandem bogies springs themself prevent the axles from going left and right. On Mack heavy series rears additional torque rod is installed connecting one of the carriers to the frame rail for taking that kind of stresses.

[6v71]

Great explanation of the two designs.  Thanks

[sodly]

Thanks for the explanations.  This is exactly as I suspected the camelback worked but never knew for sure.  Seems those rubber blocks must take quite a beating during extreme articulation situations.  There would appear to be a tremendous amount of stress on the far ends of the springs where the pack is only one or two leafs thick.  Those couple of leafs have to take all that twisting motion.  Yet, you always hear people say that a camelback is one of the toughest suspensions out there, right along side the Hendrickson walking beam, and offers unparalleled off-road traction.  

I've also seen in old Mack brochures how the camelback suspension "steers around corners" due to the spring packs lengthening and shortening on either side of the truck in a turn.  Can anyone elaborate on their experience with that?  I would think it must be quite subtle otherwise it would be an odd sensation to feel the tandems steering from the rear, even if only slightly.   

[topo]

The rubber blocks move enough to wear a hole through the bottom of the of the housing and get replaced. they are used on the suspensions with springs and the suspensions with the solid walking beam .

[41chevy]

2 hours ago, sodly said:

Thanks for the explanations.  This is exactly as I suspected the camelback worked but never knew for sure.  Seems those rubber blocks must take quite a beating during extreme articulation situations.  There would appear to be a tremendous amount of stress on the far ends of the springs where the pack is only one or two leafs thick.  Those couple of leafs have to take all that twisting motion.  Yet, you always hear people say that a camelback is one of the toughest suspensions out there, right along side the Hendrickson walking beam, and offers unparalleled off-road traction.  

I've also seen in old Mack brochures how the camelback suspension "steers around corners" due to the spring packs lengthening and shortening on either side of the truck in a turn.  Can anyone elaborate on their experience with that?  I would think it must be quite subtle otherwise it would be an odd sensation to feel the tandems steering from the rear, even if only slightly.   

This is the mounting pads and the spring /rear units. The "t" on the spring end limits the "steer". The rubber blocks and caps wear the most.