We the people of this planet tend to talk in jargon. We tend to look for cutsie ways of saying something in plain english. Text messaging is a prime example of this.
Well in the RV community we short cut all the time. A 5ver, a fifth wheel trailer. That is an easy one. the 5th wheel trailer has become the high end norm in the towed industry because the 5th wheel trailer places the weight of the trailer and all of it’s applied side forces right over the rear wheels. A TT which is the term for a travel trailer hangs the weight and the forces well behind the rear wheels and at the very back of the vehicle. This can cause a sway to be magnified by the distance behind the rear wheels that the trailer is attached.
DP, is a diesel pusher. This chassis places the diesel engine at the very rear of the rig and is called a push because the engine is mounted backwards and it drives the rear axle that is located in front of it. One plus for the pusher is that the drive shaft is usually shorter and less prone to vibration. Also a lot cheaper to make. The DP moves the engine noise to the back of the rig and is usually a heavier rig and provides improved handling. The problems are that it is next to impossible to use ram air to cool the engine radiator so that it must run a huge power robbing fan.
FRED is usually a heavier chassis than a front engine gas and is similar to a pusher but the diesel engine is at the front. It can use ram air on the up side to cool the radiator. But it moves the noise of the engine right between the driver and the co-pilot again and brings back the dog house obstruction. It also adds to the length of the drive shaft and may necessitate the addition of center carrier bearings and more universal joints and splines. Handling then moves into the class of an over the road big box truck.
IFS and IRS is how the suspension system is made. IFS means that the front suspension will be like your car. Each front wheel is its own suspension system and there is not a solid front axle between the wheels. This adds to a shorter turning radius and helps the engineer design a better ride and handling. Both of these reduce the unsprung weight of the rig and again allows the engineer to design it with lighter softer springs for ride quality.
PB&J, I was hungry, wanna bite?
Well the question is which is the best? Well that question always plagued me for the 40 or so years that I was writing my syndicated auto column. The answer is not blowing in the wind, it is in taking your time, driving each example for more than just a spin around the block, and then sleeping on it long enough to weigh it all out. Each has pluses and minuses that only you can answer for you. Oh, remember that if a salesman puts the “gotta have a descision today” pressure on, the answer should always be no.
Good luck, sure you don’t want a bite of my sammich, it’s grape jelly?