Please use this identifier to cite or link to this item:
Title: Studies on vehicular trafficability of snow : part 2
Authors: Lanyon, John J.
Keywords: Snow
Tracked vehicles
Snow cover
Publisher: U.S. Army Snow, Ice, and Permafrost Research Establishment.
Engineer Research and Development Center (U.S.)
Series/Report no.: SIPRE report ; 35 pt.2.
Description: Technical report
Summary: Trafficability studies were conducted at USA SIPRE Keweenaw Field Station, Houghton, Michigan, during the 1955-56-57 winter seasons to evaluate the traffic-supporting capacity of a snow cover as influenced by preceding and current meteorological phenomena and the metamorphic processes in the snow. Studies conducted in Greenland during the summer of 1956 were directed toward an investigation of the effect of climatological variations and the related physical properties of the surface snow layers in North Greenland on the mobility of tracked vehicles. The vehicles used in the studies at the Keweenaw Field Station were the M-7 Ordnance snow tractor and the 4-pontoon Tucker Sno-Cat (Model 443). A small commercial tractor developed for operation on muskeg and snow was modified and instrumented for use as a trafficability testing dynamometer vehicle at the Keweenaw Field Station. A roving field test station was used in the Greenland Ice Cap studies. This station consisted of an M-29C weasel pulling a light wannigan and a 1-ton cargo sled. It accompanied the heavy freight and passenger tractor-train swings from the TUTO ramp at the edge of the Ice Cap to Site 2, located at an elevation of 6800 ft about 200 miles east of TUTO. When the M-7 snow tractor was loaded with concrete blocks, it was found that the maximum drawbar pull was obtained at a mean ground pressure of 1 psi. The maximum efficiency for this tractor occurred between 10 and 20% slip. The efficiency coefficient of the Tucker (Model 443) was found to exceed that of the M-7 snow tractor by 4%. The trafficability studies in Greenland indicated that drawbar pull is directly related to both the density and hardness of the top 50 cm of snow. Hardness, as measured by a drop cone penetrometer or a shear vane, was independent of density within the limited range of snow density encountered on the Greenland Ice Cap. Face-angle grousers of the Kamm type were compared with grousers cut to the same profile from angle iron. Both types were tested on the track pads of the M-7 snow tractor. Although an increase in drawbar pull of 30% was obtained with supplemental grousers, the overall results did not appear to justify the use of a face-angle grouser. It was found that more tractive force is developed on the rear pontoons than on the front pontoons of the Tucker Sno-Cat, indicating that a broken rear track may be replaced with one from the front pontoon to increase the tractive effect of the crippled vehicle. An instrumented single track pad was designed and tested. With further refinement, this instrumented pad may make it possible to measure independently the several forces acting on a track section. Any apparent conflicts between the results reported in Part I and Part II of SIPRE Report 35 may be considered as supporting evidence that variations in the properties of the snow cover are so large that all combinations of parameters which may effect trafficability cannot be evaluated in several seasons of testing.
Rights: Approved for public release; distribution is unlimited.
Appears in Collections:Technical Report

Files in This Item:
File Description SizeFormat 
SIPRE-Technical-Report-35-Part-2.pdf14.78 MBAdobe PDFThumbnail