Abstract: Access to an operator station of a large track-type tractor is provided by a ladder support structure pivotally attached to a portion of the radiator guard of the tractor. The ladder support structure extends over a track of the tractor and has a ladder pivotally attached to a distal end of the ladder support structure that provides steps over a push arm and a tilt cylinder of the tractor. When the ladder assembly is moved to its carry position, the ladder is moved to a position inside the ladder support structure, and the ladder support structure raised to a vertical position adjacent a side panel of the radiator guard of the tractor. The present invention avoids the problem of machine operators climbing on the push arms, tilt cylinders, radiator, radiator guard, track, hood, and engine enclosures in order to gain access to the operator station.

Abstract: An engine control system is provided which calculates an optimum air/fuel ratio by minimizing the smoke produced by the engine while at the same time maximizing the engine response time for all altitudes over which the engine operates. The control system includes a microprocessor, an ambient pressure sensor, fuel injectors, and storage means. A manual adjustment is provided that allows an operator to manually adjust the air/fuel ratio within certain pre-defined limits of the optimum value.