Rear Differential Design: The Cause of Washboard Roads?

[zedex]

After going up in the mountains where i live i started getting annoyed at how washboard the roads were. Logging trucks go up this road a lot.
Is the design of the rear differential to blame for washboard roads? Seems to me to be the case since the bumps are evenly spaced.
Cheers

 

[Integral]

I would be more likely to believe that suspension systems are to blame. Others may know more.

 

[jdavel]

zedex,

I noticed this washboard effect once in northerrn Illinois where there are absolutely no hills. It occurs on roads that are basically dirt with just an oily tar coating, that is the surface is not very stable. It also occurs only at intersections (before the road crosses the other road). My theory was that it's caused by the constant breaking, which pushes forward on the road as cars come to a stop. The effect on other parts of the road where cars aren't accelerating as much or as often would be far less.

In the mountains just going up and down hills requires a lot of force being applied to roads, and with big trucks, even more force.

Anyway that's my guess.

 

[pallidin]

I agree with Integral. A standard vehicle has 2 primary suspensions; front and rear. Load forces are placed via the wheels on roads, and a moving vehicle generally has asymmetric loading on suspension, usually(though not always) with the greater load on the rear. Compressible road surfaces are affected under these circumstances. "Washboarding" results.
Factors including vehicle speed, total gross vehicle weight, axil loading differentials, axil spacing, road composition and traffic throughput have influence.
A heavily traveled compressible road surface often has more tightly space "washboards" due to the collective effects noted above.

 

[zedex]

excellent. Makes sence. Thanks guys.