Tuesday 10 September 2019

Importance of Rear Axle Alignment on heavy Trucks

A properly aligned front end has long been established as a necessity for long tyre life, handling ease, and driving safety, as well as a factor in achieving optimum fuel economy

However, until recently, little attention has been focused on the alignment of the rear axle. A misaligned rear axle may result in:

a) Reduced tyre life;
b) Difficulty in driving;
c) An unsafe vehicle;
d)Less than optimum fuel economy.

According to our studies, "It has proven that 80% of  Multiaxle trucks are operating misaligned, and over 90% of the trucks they pull have serious alignment problems." The majority look like those in Figure 2.



A misaligned rear axle causes excessive tyre-to-road drag and creates undesirable lateral forces.

Figure 1 illustrates correct tandem axle alignment.
Figure 2 illustrates some possible axle alignment conditions.

Even new trucks need rear axle alignment. 

Studies also cite that up to 70% of new vehicles need some form of rear axle alignment. In a study of around 1500 trucks, those with proper rear axle alignment vehicle having 10-20% more tyre life and having fuel saving upto 5%.

According to recent studies conducted, Additional real axle drag and scrub contributes to even more fuel loss and decrease in tyre life. "Sixty percent of steering axle tyre wear is caused by drive axle misalignment."

All heavy trucks and trailer units should have their rear axle alignment checked and adjusted periodically or when any abnormal tyre wear appears. Rear axle alignment should be checked after any collision repair. Minor shifts in the frame-to-suspension mounts may cause significant shifts in both front and rear axle alignments. To align the front axle will only fix half the problem.

Below figure illustrates various effects on fuel consumption. Drag and tyre rolling resistance accounts for the single largest segment of fuel consumption - 42.2%. Any action taken to reduce rolling resistance, such as proper alignment, can and will reduce fuel consumption.


It is possible for a given truck to have reciprocal rear axle misalignment conditions. If this were the case, it may not exhibit any poor driving characteristics. However, tyres will still wear and fuel economy will be decreased.

Tyre Wear usual suspects:

Rear axles usually have little or no camber and toe requirements.

Heavy trucks rear axles use no caster alignment correction.



©️ 2019 A2s Truckinfo.

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