A giant "snow cruiser," specially designed to span yawning crevasses and jagged ice ridges, may be a major piece of equipment on the government’s forthcoming expedition to the Antarctic continent. Secretary Ickes told reporters yesterday that every effort would be made to start the trip by September 30. Congress has appropriated $340,000 for the expedition, which will make formal claim to a vast segment of the icy regions lying east of Little America. Details of the snow cruiser, which will rely on tractor treads far mobility, are closely guarded by its designer, Dr. Thomas C. Poulter of Chicago, second-in-command of the Byrd Antarctic Expedition in 1933- 35. His recent testimony before a House appropriations subcommittee indicated that the odd craft could carry sufficent equipment for an exploring party to last a year. On its deck, Poulter suggested, the machine could carry a Navy pursuit plane, which, by making short flights at 300-mile intervals, could explore about 5,000,000 square miles of unknown territory during a single Antarctic summer. Poulter is scientific director of the Research Foundation of Chicago, a corporate organization affiliated with the Armour Institute of Technology, He said the foundation hoped to finance the vehicle’s construction, but that plans were still indefinite. United States claims to a section of the South Pole region are based on explorations by Byrd and Lincoln Ellsworth. The former has been mentioned as the possible leader of the new expedition, which will make scientific studies as well as plant an American flag over the claimed territory. This nation is not alone in seeking to assure itself of a share in any future development of the ice-covered continent. A German expedition last spring laid claim to more than 135,000 square miles of the Antarctic east of the Weddell Sea area. A few months earlier Norway asserted its sovereignty over a great portion of the continent, including part of the German field of work; Great Britain, France and Japan also have advanced claims to sections of the Antarctic at various times.