Hot Weather Operation Considerations

When we refer to hot weather operation, we are referring to ambient air temperatures greater than 95 degrees farenheit. The higher the temperature climbs, the greater the importance of these considerations.

Tire Considerations

The number one cause of tire failure, is heat. When you run a tire under inflated, the friction from being low causes damaging heat generation. The same friction which makes your brakes work, destroys your tires. Bias ply tires are much more susceptible to under inflation self destruction due to the way the bias ply tire is constructed. If you have tubes inside the tire, under inflation causes the tube to work within the tire which causes more heat generating friction.

If you plan to drive a lot in very hot climates, you should not consider tire caps. The caps are most susceptible to heat. The best way to extend tire cap life is to keep them fully inflated at all times. All of these tire factors are severely aggravated during hot weather driving.

Radiator Fluid Control

The first most important thing you can do is keep a 50% antifreeze solution in your radiator. This provides several advantages. First, it reduces radiator fluid expansion. The antifreeze expands less at high temperatures than does plain water. The 50/50 solution also increases the boiling point of the solution, so there is less chance if boiling fluid from your radiator.

The anteater trucks (low front profile) have an additional problem to consider. Due to the low frontal area of this design, the top of the radiator is lower than the top of the engine. Water is added through a reservoir recovery tank. With this design, any time the radiator gets a little low on fluid, then the cylinder heads of the engine have no cooling water.

The recovery tank is there to hold the expanded hot water. If the recovery system is not working properly, expanded water is not recovered when the engine cools off. Using antifreeze reduces the expansion problem, which reduces the possibility of boiling out the radiator fluid.

Bugs Amongst Us

It is surprising how many trucks run around with large quantities of bugs caked onto the radiator fins. The little critters interfere with air flow around the radiator fins, and can have a pronounced impact upon engine cooling temperature rise. The easiest way to control the bugs is to place some window screen in front of the radiator, and simply replace the screen once it has collected a sufficient number of critters.

Fast Idle

If you leave your engine idling for extended periods, it is recommended by the engine manufacturers to increase the idle speed to 1000 - 1200 RPM. The fuel injection systems are not efficient at idle speed, so that excess fuel causes carbon buildup inside the engine. Most of the newer E-engine trucks with cruise control have a feature to advance the idle speed of the engine. The older models usually offer a dash controlled engine speed setting.

Braking Considerations

Your brakes work because of heat generating friction. The hotter the ambient air temperature, the longer it takes your brakes to dissipate the braking generated heat build up of the brake shoes and drums. During hot weather operation, you should avoid lengthy light brake applications. Use shorter and heavier braking, road conditions permitting, because that reduces the prolonged heat build up of long term light braking.

The greater the temperature difference between two substances, the greater the heat transfer characteristics. When you do short hard braking, the increased brake drum temperature will dissipate heat to the ambient air faster than the lower temperature generated by prolonged light braking. Reduction of vehicle speed takes a certain amount of energy. The harder you brake, the more peaked is the energy braking temperature, therefore the greater the heat transfer away from the brake drums.

Road surface should always be factored into braking pressures. With rain soaked road surfaces, you obviously can not perform peaked braking, and must resort to less braking pressure for a longer time.

We have noticed that some of the newer trucks don't have a trailer brake handle. One situation where we think this is dangerous, is when the tractor-trailer entesr into a curve with to much speed. Some times the driver is caught unaware, and finds the speed to be excessive for the curve. In this situation, heavy braking pressure could put you into a jackknife without a trailer brake handle. When centrifugal forces are already heavy, the addition of heavy braking will result in a vector pushing force of the trailer which will add to the centrifugal force, which will increase your problem situation. Use of the trailer brake handle alone, helps to prevent the jackknife in this situation. If you are driving without a trailer brake handle, you had better pay more attention to your entry into curves!

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