Mack Camelback  Suspension Issues Explained

In this brief article we are going to discuss the different  Mack Camelback  Suspension problems, what the causes are, and Troubleshooting Tips.

What are the most common  Mack Camelback  Suspension issues? 

The most common  Mack Camelback  Suspension issues are:

  • Axle Excessive lateral movement
  • Frame lateral connecting rod crack
  • Leaf Spring breakage
  • Control Arm Bush Wear out
  • Tyre Scrubbing

Mack Camelback Truck Boggie Suspensions 

The Camelback Suspension is derived from the traditional “Boggie” suspension that was used in Rail wagons since the early days of rail transport.

In the Cameback’s basic structure consists of 

  • an Inverted Leafspring that is hinged at the frame via a “Trunnion” bushing and Bearing 
  • Leafpsring attached to the axles via Flexible Load Pads housed in a Box bracket with Lateral Spacer Bushings
  • Axles attached to the frame via Torque rods

Axle Excessive Lateral Movement

  • The axles move laterally during turning short with a load
  • The movement would be upto 2 inches
  • The factors influencing this excessive movement would be the 
    • Axle Load Pad insulators (top, bottom and lateral)
    • Trunnion Bushing
    • Leaf Spring Pack U-Bolt Preload
  • Older models like the 38K did not have the lateral spring load pad insulators (yellow in diagram above). If this was missing then it could be added and will help reduce axle lateral movement
  • Replacing all suspension bushings with aftermarket Polyurethane equivalent bushings would improve the overall suspension performance under load
  • Certain aftermarket additions like an additional Lateral control rod would help a great deal. 
  • The lateral rod aftermarket solution would be available as a package with a rod and brackets that bolt on to the frame side rail and the axle housing Top

Frame Lateral Connecting Rod Crack

  • The Lateral rod connecting the left and right Trunnion brackets gets cracked
  • This happens over a long usage period and is normal
  • The reason for it is continuous frame twist loads over a period of time that have got transmitted through the suspension 
  • This sort of failure also means that the entire suspension needs to be checked for wear. Ideally, the suspension is supposed to take up a major portion of road loads before the load is transferred to the frame. But in the case where there is excessive suspension wear, a larger portion of road loads may be taken up by the chassis frame

Leaf Spring Breakage

  • Depending on the type of application, the leaf springs either wear out faster or slower.
  • If your truck is applied at a site where is maximum amount of axle articulation, the springs would be put to work extra hard in order to cope up with the terrain
  • Leaf springs, by design, fail due to fatigue. Fatigue means a low to moderate load (that is way below the spring load capacity) applied continuously over a long period of time. This is different from a single sharp high load impact on the spring.

Control Arm Bushing Wear out

  • The Control Arm/Torque Rod Bushings tend to wear out quickly as they are made of Rubber
  • Once these are worn out, there will be noticeable change in the handling behaviour and also tyre wear
  • The rear suspension will feel loose and unstable in high speed
  • Aftermarket Polyurethane material Bushings tend to give better performance in terms of durability and long-term elasticity retention.

Tyre Scrubbing

  • Uneven Tyre wear on the wheels
  • The reason this happens is due to the tires missing their alignment 
  • The best way to deal with  it is to get the alignment done at a place that does alignment for Trucks. Car and Van alignment shops might not be able to do a good job.
  • If an alignment did not solve the issue, then it might be the case that the suspension bushings have failed. 
  • The factors influencing this excessive tyre wear would be the 
    • Axle Load Pad insulators (top, bottom and lateral)
    • Trunnion Bushing
    • Leaf Spring Pack U-Bolt Preload
  • Also check the center distance between the axles on both sides. Use the in-built adjustment to align the axles back to the manufacturer recommendations.

Conclusion

In this brief article we have discussed the different Mack Camelback Suspension problems, what the causes are, and Troubleshooting Tips.

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