TDR - THE LAWS OF PHYSICS 

2000 was a remarkable year.  Diana and I had been planning the purchase of a coach for business purposes as well as for an occasional fun trip.  As Mr. Patton was quick to point out, our new motor home was a gas job, but only because it was about 40K more to step up into a diesel pusher.  I really lusted for about a 40 footer with a 300 Cummins in back pushing through a six speed Allison.  C’mon Georgia Lottery !!

Diana and I educated ourselves as best we could using the internet, RV magazines, and several visits to local dealerships. After shopping carefully, we picked out  “Shadow”.  She was a 32-foot  “Shadow Storm”, manufactured by Fleetwood Industries.  Shadow derives her thrust from a Fuel injected Ford Triton V-10 truck engine, coupled to Ford’s new 4R100 overdrive automatic.  The final drive is a DANA 80 limited slip sporting a 5.39 axle ratio.  How’s about plugging that ratio under your Cummins powered dually??  The coach had a “Slide”.    When parked, the living room and dinette extend out from the left side about 3 feet.  This made it super roomy, and perfect for a party.

Oops!  Don’t hit the switch and extend the slide until you have extended the four hydraulic leveling jacks.  Why?  It’s a law of physics.  The coach could tip over.  Not Good!

Shadow weighed in at about 16,000 pounds. That’s not a lot for a “Class A” motor coach.  The diesel pushers exceed 30,000 pounds.  Once these huge vehicles begin to move, the forces that go to work can be pretty exciting. These forces include, but are not limited to Kinetic Energy, Momentum, Inertia, and Wind Resistance.  Being a “Class A” means a square frontal area (like any bus) that’s the equivalent of pushing a garage door through the air at 65 miles per hour.  That’s wind resistance.  No respectable motor home manufacturer publishes coefficient of drag numbers.  Kinetic Energy comes into play even with massive four-wheel disc brakes.  Running downhill at 65, you cannot stop on a dime.  More like the National Debt to stop.  And finally, when facing uphill and attempting to start off from a red light or stop sign, the V-10 worked super hard to overcome inertia.  More laws of physics.

How about “Centrifugal Force”?  Try cornering with a top heavy (super high center of gravity) bus when running at speed into a decreasing radius exit ramp.  Talk about plowing or under steer, WOW!  Forget about  “Lateral G Forces”.

What’s all this mean?  You can’t step out of your Bimmer convertible and jump into the driver’s seat of a bus and act the same way. (Well, you could, but not for long.)

Diana and I purchased “Shadow” in July 2000.  We have really enjoyed traveling with the motor home lifestyle.  We can’t wait for a real vacation trip.  Diana might just sign up for professional bus driving school, and will attend the six-day course soon (maybe).

We decided to preserve our fantastic relationship and have a professional instructor impart his knowledge to her.  Then I can go to the master bedroom and catch up on some sleep as we motor on down the road to the next gig.

That may not be a law of physics, but I’m sure it qualifies as some sort of law!

These same laws of physics apply to each and every one of us.  So when you get under the hood of your Dodge Turbo Diesel and plug in that new electronic box good for 150 plus horsepower and 200 foot pounds of torque, try to remember the torque load and clamping force your OE clutch was designed for.  Breaking the laws of physics will make it smell and let the smoke out.

Likewise for the automatic transmission.  Increasing the power exponentially, and hammering the throttle will take those little friction plates and the ceramic torque converter clutch, and turn them into a fine powder we call dust.  If you turn up the power, and increase the critical mass of your right foot, you will need to make other modifications to go along with it.  For the automatics, there are electronics available to control shift points and hydraulic line pressure.  A must for modified engines.  Increasing the line pressure improves shift crispness, and helps to prevent clutch shudder.

This will definitely extend the life of your automatic transmission.  Don’t forget the “Lubegard Automatic Transmission Protectant”.

For you manual gearbox folks, there is a complete selection of “Stronger than stock” clutches available.  Bear this in mind.  The more pressure the clutch cover exerts on the disc against the flywheel, the more work your hydraulic clutch slave and master cylinders have to do.  Work them harder, and they will fail earlier.

I replaced the three universal joints and the center support bearing on Midnight’s drive shaft.  I finally got around to the installation of the “Polyurethane” mid ship bearing from Inland Empire Driveshafts in California. When the two halves were apart, I couldn’t help but wonder how the slip joint’s splines could handle all that power pulling all that weight.  It’s engineered to do it, but that engineering is based on the engine’s original power output, and not exceeding the trucks rated capacities for loaded weight and / or towing.

I know in my heart that none of us ever exceed the load ratings, or increase the power output, but let your mind soar.  If we purchase a truck with 230 HP and 450 foot pounds of torque, and the trailer towing capacity is 10,000 pounds, how would the laws of physics apply when we run 300 plus HP @ 700 foot pounds of torque to drag our 20,000 pound trailer?

The answer is simple!  Gravity.  Yep!  (Pardon the Pun) We’ll break “down”.

In the areas of preventive maintenance, here I go again.  This is my pet thing to do because it’s so important, yet often overlooked.  Change your brake fluid once a year.  It’s relatively simple and inexpensive compared to the alternatives.  Fluid is non compressible, but old brake fluid is easily boiled under heavy brake applications.  Remember back to eighth grade physical science.  When you boil a liquid, it becomes a vapor.  Try to pump up a fading brake pedal when the lines are full of vapor.  Good Luck!  No Pedal, No stopping!

Another one of those silly Laws of Physics !

Here’s a practical application of “The Laws of Physics”.    

Last year’s repertoire of jobs (I can’t hold a real job) included several days of research and training with my friends at the ABS Education Alliance.  Five years ago I traveled the country on a media tour, which included visits with the best and most influential automotive reporters.

The purpose then was to disseminate real information regarding Anti Lock Brakes.  The ABS Education Alliance was providing information to consumers regarding the newest vehicle safety technologies.

The newest technology is called “Intelligent Stability and Handling Systems”.  This is a category name.  You may have heard these systems called “Stabilitrac”, “ESP” or “Electronic Stability Program”, “VSA” or “Vehicle Stability Assist”. “DSC” or Dynamic Stability Control”, or a host of other names and acronyms.

With various manufacturers using different names, the consumer is again tasked with weeding through and differentiating so as to understand what a vehicle may be equipped with.  The Alliance conducted extensive research using industry experts as well as consumer focus groups to arrive at the broad category name.

By using a “category” to cover all these systems, confusion should be minimal.  Here’s how these systems work.  With ABS brakes installed on a vehicle, the hardware was in place for the next step, “Traction Control”.  Using the ABS electronics and mechanical platform, traction control was added to reduce unwanted wheel spin or traction loss on slippery surfaces, such as rain, snow, loose gravel, etc.  Some traction control systems actually retard throttle application as well as applying individual wheel brakes to control wheel spin under acceleration.

ABS Brakes monitor wheel speed, and when wheel lock is eminent, ABS modulates brake pressure to prevent skidding and loss of steering control.  These same wheel speed sensors feed information to the “Electronic Control Unit” for traction control.  Both of these safety systems work very well, but only monitor wheel speed, vehicle speed, and have no idea of dynamic forces acting on the vehicle.  Here’s where “The Laws of Physics” comes into play.

The newest generation of vehicle safety technology is found in the “Intelligent Handling and Stability Systems”.  The reason for the term “Intelligent " is simple.  For the first time, vehicles equipped with this system have a sensor that actually detects the position and movement of the vehicle in relationship to steering input.  

When a vehicle is traveling at speed, and the driver steers left, but the vehicle tries to go right, (a skid), the system automatically intervenes, and applies individual wheel brakes to prevent the skid.  This intervention allows the driver to maintain directional control or “Stability”.  Intelligent Stability and Handling systems can correct for over steer and under steer.

All of this is designed to make driving safer.  YOU CAN exceed the capability of these new systems.  Again, a vehicle is governed by the “Laws of Physics”, and if you exceed things like the coefficient of friction, centrifugal force, and momentum, you pay the price.

There is no substitute for a responsible driver, and these safety systems are NOT designed to allow you to drive more aggressively, but rather to assist when the unexpected happens and a violent maneuver is called for.  To learn more about these great systems, you can log onto the website www.abs-education.org.  

Look for more “Intelligent Technology” in the near future. 

As always, Keep on Trucking.

Sam