ANALYSIS OF THE DESIGN AND OPERATING CHARACTERISTICS OF THE SIGMATIC PS WIDE‑WIDTH IRRIGATION MACHINE WITH A SWIVEL PIVOT SHAFT

Based on the technical description, factory operating manuals, and archival materials of the VHJ Sigma Olomouc concern (now Sigma Group a.s.), the article provides a comprehensive historical and technical analysis of the Sigmatic PS wide‑area circular sprinkler machine with a swivel trunnion, which was put into mass production in 1986. The article examines the prerequisites for the machine’s development, which were driven by the insufficient productivity and high labour intensity of belt irrigation systems, as well as the objective need to automate the irrigation of large agricultural areas within the optimal agrotechnical timeframe. A structural scheme has been reconstructed, including a universal prefabricated modular truss made of bridges 6 m long with hinged joints, support trolleys with an individual electric drive of 1 kW, a water supply system via a swivel trunnion from an underground pipeline, and filtration units. The following quantitative parameters are provided: irrigated area from 5 to 50 hectares, irrigation capacity of 20–50 L/s, operating pressure range of 350…750 kPa, and the ability to adjust irrigation rates within the range of 4…70 mm, depending on the type of tires. The machine demonstrates adaptability to various operating conditions, including operation on sloped land with a gradient of up to 15° (depending on the span length and furrow depth), irrigation of tall‑stemmed crops (corn, cereals), and the ability to apply liquid fertilizers and mechanically treated wastewater. The system of automatic control is described, which provides motion reversal, regulation of the overlap from 10 to 100 %, local and remote control, as well as comprehensive emergency protection in case of hose breakage, motor overload, pressure drop, or water temperature below +5 °C, with automatic shutdown and light signaling. Diagnostic functions are provided to facilitate fault detection, and protective measures for personnel safety are described (insulation of live parts, lightning protection, casings on rotating elements). It has been demonstrated that the Sigmatic PS represents a representative example of the stage in the development of wide‑spanning sprinkler irrigation equipment associated with the transition from hydraulic systems to electrified, automated, and modular circular machines, which has significantly increased labor productivity and the efficiency of water resource use.