Study on Steerability of Tracked Tractors (Part 1)

On Analysis of Uniform Turning Motion

Abstract

Several papers have been published on the subjects of steerability and trailer towing performance of the wheeled tractor. However, there has not been any article dealing with the same subject of the tracked tractor, because the phenomenon of those dynamic motions between tracks and ground is very complicated.
This paper describes a theoretical analysis of uniform turning motion of tracked tractor with wheeled trailer. Considering all possible factors related to steering problems such as track slippage, towing load and length of towing bar, equations for uniform turning motion have been developed in order to analyze and predict steering dynamics and steerability in the plane motion of the vehicles. These equations have been numerically solved by a digital computer and the reliability of the above analysis has been confirmed experimentally by using the scale models.
The results are summarized as follows;
(1) The equations of turning motion presented here provided a reasonable means for a dynamic analysis of the tracked towing vehicles.
(2) The turning radii are closely connected with towing weight and track slippages, and they increase rapidly when the towing weight increases.
(3) The turning radii of tractor and trailer are not related to the length L₂ of towing bar at L₂<L (track contact length), however, at L₂>L radii are affected considerably.
(4) The steering characteristics of tracked towing vehicles tend to oversteer at higher speeds as shown in Fig. 10.