We all have heard of shock absorbers, but do we know where they are and what they do? It is a rare occasion that you would find an on highway vehicle that doesn't have shock absorbers (from here on we will just call them shocks). Even race cars and off road vehicles have shocks, they play a very important role in traction control. Some believe shocks support the weight of the vehicle, they do not support any weight.
Shocks are mounted at the top to a solid point that is not a moving part of the suspension, usually the frame of the vehicle. The lower mount is bolted to the axle itself (on a truck) using a bracket made just for the shock. To find the shock on a truck, look for a tube about two inches in diameter that looks like it has two parts. One tube fits loosely inside the other; these will be attached at both ends to the truck. The one on the passenger side is easier to find on the steer axle, than the one on driver's side.
The shocks on the drive axle are easy to see from the rear, mounted near the spring mount on the axle housing. Again on the frame at the top of the shock using a special bracket usually. The shocks usually stand nearly perfectly vertically over or just behind the axle so that they will follow the travel of the axle.
Every time a tire hits a bump or a depression in the road (pot hole) the shock goes to work. The suspension, springs and/or air bags, carry the weight of the vehicle and its load. As a truck weighs and carries a lot of weight, the suspension is very stiff. The shocks dampen the shock of the impact of any road deformation. They will not eliminate the shock and that is why you still feel every bump. The purpose of shocks is to keep the tire on the road, improving the ride is a side benefit.
Shocks are basically a hydraulic pump, as you go over bumps the shock "strokes" and oil moves through valves from one side of a piston to the other, at a controlled rate. This rate is determined by the weight of the vehicle and its estimated load, by the vehicle engineers. A working shock will be warm after traveling. The shock changes kinetic energy (the movement of the suspension) into heat, which it then dissipates.
So you may ask, why do you need to keep good shocks on the truck if they don't improve the ride? One reason is they will help the steer tires last longer; keeping them from bouncing will avoid some odd wear patterns. If the shocks are worn out, the hit of the rough road transfers directly into the chassis, things will start breaking and you will be more fatigued at the end of your shift. Keeping good shocks on the drive axles will help with tire wear and some traction issues.
Bottom line is keeping good shocks on the truck will reduce your cost per mile. Shocks are fairly easy to replace, watch this short video to see how to change a shock on the steer axle. You may notice I installed Monroe gas shocks instead of standard oil filled shocks; it was all that was available when I went in to get the new shocks. Oh well, I think they will work fine until next time, we'll see.