The Construction and Operation of Six-Wheel Trucks 360135
BOTH the tractor-semi-trailer and the six-wheel vehicle have the same number of axles and wheels and each has its own particular advantages. They are seldom competitive if the transportation problem is analyzed properly and legislation does not unduly oppress either. The six-wheeler has the advantage over the tractor-semi-trailer of weight saving, more traction if four driving wheels are used, lower insurance rates, and it is free from any “jack-knifing” proclivities.
The chief distinction in the construction of six-wheelers depends upon the types of axles used, whether they be dead or driving. There are five classifications in use today, ranging in various combinations all the way from three driving axles to one. The rear bogie unit may have two driving axles or a driving and a trailing axle.
There is a natural resistance to turning in a bogie unit since the wheels do not roll tangentially when the vehicle travels around a curve. Considerable research is required on the subject of steering geometry on a six-wheeler.
A number of foreign trucks have applied individual wheel suspension to the bogie wheels. A foreign and a domestic design each provide an engine at each end of the vehicle, each one driving an axle of the bogie.
Great interest is being shown by the oil companies in the use of light-weight six-wheelers for oil and gasoline distribution because of their agility in covering greater mileage than the heavy-duty four-wheelers they are replacing.